Troubleshooting and Repairing Major Appliances

CHAPTER

Automatic Electric Dryers

Automatic electric dryers are not complicated to repair. The more you know about the electrical, mechanical, and operational basics of the dryer, the easier it is to solve the problem. Some models are designed to operate on 240 volts; other models operate on 120 volts. To dry clothing, an automatic dryer must have drum rotation (clockwise rotation at 40 to 60 RPM), electric heat (approximately 5600 watts), and air circulation. This chapter will provide the basic skills needed to diagnose and repair automatic electric dryers. Figures 20-1 and 20-2 identify where some of the components are located within the automatic electric dryer. However, this illustration is used as an example only. The actual construction and features might vary, depending on what brand and model you are servicing.

FIGURE 20-1 The location of components in a typical automatic electric dryer. The consumer has a choice between a drop-down or side-open door.

FIGURE 20-2 Typical component location in an electric dryer.

Principles of Operation

The clothes are placed into the dryer according to the manufacturer’s recommendation for the proper loading of the dryer. Next, the proper cycle is selected, and the dryer start button is pressed. The combination of the timer, the switches, thermistors, and/or the thermostats regulates the air temperature within the drum and the duration of the drying cycle. During the drying cycle, room air is pulled into the dryer drum from the lower rear (or sometimes the front) of the cabinet, depending on which model the consumer owns (Figure 20-3). The air is pulled through the heater, drum, lint screen, down through the lint chute, and through the fan housing. It is then pushed out of the exhaust duct. The drive motor, blower wheel, belt, and pulleys cause the drum to turn in a clockwise rotation at 40 to 60 RPM and the air to move through the dryer. The belt wraps around the drum, motor pulley, and idler pulley. The blower wheel is secured to one end of the drive motor shaft, or there may be a separate motor to turn the blower wheel. As the drive motor turns, the drum rotates, moving the clothes. At the same time, the blower wheel turns, moving the air. The heating element will cycle on and off, according to the temperature selected.

FIGURE 20-3 Typical air flow pattern in an automatic electric dryer.

Functions and Cycles

Electric automatic dryers use three basic functions to operate:

• Heat is supplied by a resistance-type heating element.

• Air is drawn into the dryer. It is heated and circulated through the tumbling clothes. Then the warm, moisture-laden air is drawn through the lint screen and is vented through the duct system to the outside.

• Tumbling of the clothes is accomplished with a motor that drives a belt, which rotates the drum.

The cycles of an electric automatic dryer are as follows:

• Timed dry cycle The timed dry cycle is controlled by the amount of time selected on the timer. The temperature in the dryer is controlled by a thermostat or a thermistor, which turns the heating element on and off throughout the timed cycle.

• Automatic dry cycle The automatic dry cycle is not controlled by the timer. This cycle is controlled by the cycling thermostats or thermistors. Heat is supplied to dry the clothes, and it will continue until the temperature in the drum reaches the selected cutout setting of the thermostat or thermistor. When the thermostat or thermistor is satisfied, the heater shuts off and the timer motor is activated. However, certain variables can control the cycle, which will cause the cycling of the thermostat or thermistor before the end of the cycle.

• Permanent press and knit cycles The permanent press and knit cycles are controlled by the amount of time selected on the timer. The temperatures of these cycles are controlled by the temperature rating of the cycling thermostats or by the thermistors that are located within the cabinet, on the exhaust duct, and in the air supply. On some models, the user can select the desired type of heat setting with the temperature selector switch, located on the control panel.

• Air dry The air dry cycle is controlled by the amount of time selected on the timer. This cycle uses the air to dry the clothes. The heating element is not used at all during this cycle.

Safety First

Any person who cannot use basic tools or follow written instructions should not attempt to install, maintain, or repair any automatic dryers. Any improper installation, preventive maintenance, or repairs could create a risk of personal injury or property damage.

If you do not fully understand the installation, preventive maintenance, or repair procedures in this chapter, or if you doubt your ability to complete the task on the automatic dryer, please call your service manager.

The following precautions should also be followed:

• Never bypass (or interfere with) the operation of any switch, component, or feature.

• The dryer exhaust should be vented properly. Never exhaust the dryer into a chimney, a common duct, an attic, or a crawl space.

• Be careful of sharp edges when working on the dryer.

• The dryer produces combustible lint, and the area should be kept clean.

• Never remove any ground wires from the dryer or the third (grounding) prong from the service cord.

• Never use an extension cord to operate a dryer.

• The wiring used in dryers is made with a special heat-resistant insulation. Never substitute it with ordinary wire.

Before continuing, take a moment to refresh your memory of the safety procedures in Chapter 2.

Automatic Electric Dryers in General

Much of the troubleshooting information in this chapter covers automatic electric dryers in general, rather than specific models, in order to present a broad overview of service techniques. The illustrations that are used in this chapter are for demonstration purposes only to clarify the description of how to service dryers. They in no way reflect upon a particular brand’s reliability.

Electrical Requirements

Electrical dryers can be connected to an electrical power source in three ways:

• Electrical cord and plug, which plugs into a 240-volt wall receptacle.

• Directly wired to a fused electrical disconnect box with a built-in shut-off switch.

• Directly wired to a circuit breaker or to a fuse panel. All dryers must be properly wired, grounded, and polarized, according to the manufacturer’s installation instructions and per all local codes and ordinances.

Electrical Plug Connection - Three-Wire Cord

Always install a UL-approved, 30-amp. power cord, NEMA 10-30-type SRDT with a strain relief on the dryer electrical terminal block located in the rear of the dryer (Figures 20-4 and 20-5). You must follow the manufacturer’s installation instructions for installing a power cord on the dryer properly.

FIGURE 20-4 Attach the three-wire power cord to the two brass and silver terminals as shown in the figure.

FIGURE 20-5 A properly attached three-wire power cord.

Electrical Plug Connection - Four-Wire Cord

The new power cord is a UL-approved, 30-amp, power cord, NEMA 14-30-type ST or SRDT (Figures 20-6 and 20-7). The plug end is a four-prong plug. This new type of power cord will better protect the dryer and the consumer from electrical mishaps. You must follow the manufacturer’s installation instructions for installing a power cord on the dryer properly. You will need an electrician to replace the old three-prong receptacle with a new four-prong receptacle.

FIGURE 20-6 Attach the four-wire power cord to the two brass and silver terminals as shown in the figure. Attach the green wire to the cabinet.

FIGURE 20-7 A properly attached four-wire power cord.

Electrical Tests for Electric Dryers

While performing a service call on an electric dryer, the following electrical tests should be performed:

• Continuity Use your multimeter and set it on the ohms scale. When measuring resistance between the terminal block ground and any exposed unpainted metal cabinet component, including control shafts and switches, there should be no more than .1 ohms resistance reading.

• Motor power Perform an audit on the motor (power required after 20 seconds with no load, and the motor is turning in the clockwise direction, and the electric heater is turned off). The reading should be between 200 and 280 watts. Next, perform a line test (power required after 1 to 5 seconds with no clothes in the dryer, the motor is turning in a clockwise direction, and the electric heater is turned off). The reading should be between 210 and 290 watts. If you do not have a wattmeter, use the Ohm’s Law formula to convert to watts.

• Low voltage start The minimum voltage needed to start the dryer motor is 100 VAC, 60 Hz (200 volts for 230 VAC, 50 Hz dryers). Place about 25 pounds of clothing with 100 percent moisture into the dryer and set the dryer at its maximum heat setting. Turn on the dryer and measure the voltage at the start of the dryer cycle. The voltage should not be below the listed voltage for any part of the cycle.

• Drum temperatures The following test will be run with the exhaust duct vent disconnected from the dryer. Take your multimeter temperature thermal couple and place it in the lint grill about 1 to 2 inches. You will need to set the dryer timer as needed for this test. The recordable temperature is to be the maximum temperature reading after the third cycle when the heater cycles off. There should not be any clothes in the dryer for this test. Each time the thermostat or thermistor cycles open, there should be equal to or higher than opening temperature for the next lower temperature setting.

• Maximum heating temperature when the heater cycles off is 120 to 160 degrees Fahrenheit.

• Medium heating temperature when the heater cycles off is 110 to 140 degrees Fahrenheit.

• Low heating temperature when the heater cycles off is 95 to 130 degrees Fahrenheit.

Location and Installation of Dryer

The following are some general principles that should be followed when installing a dryer:

• Locate the dryer where there is easy access to existing electrical lines.

• Be sure that you observe all local codes and ordinances for the electrical, plumbing, and venting connections.

• The dryer should be installed and leveled on a firm floor to minimize vibration during operation.

• To reduce the risk of fire, never install a dryer on any type of carpeting.

• For proper operation of the dryer, be sure that there is adequate make-up (new, replacement) air in the room where it is installed.

• Do not install a dryer in an area where the make-up air is below 45 degrees Fahrenheit. This will greatly reduce the drying efficiency and increase the cost of operating the dryer.

• Always follow the installation instructions that are provided with every automatic dryer purchased. If the installation instructions are not available, order a copy from the manufacturer.

• When installing a dryer in a mobile home, the dryer must have an outside exhaust. If the dryer exhaust goes through the floor, and the area under the mobile home is enclosed, the exhaust must terminate outside of the enclosed area.

• If the dryer is to be installed in a recessed area or closet area, follow the manufacturer’s recommendation for its installation.

• When relocating the dryer to a new location, test the voltage at the new location, and be sure that it matches the dryer voltage specifications as listed on the nameplate (serial plate). Also inspect the entire vent system for any obstructions.

Proper Exhausting of the Dryer

Proper exhausting instructions for the model being installed are available through the manufacturer. Each manufacturer has its own specifications for the size and the length of the ductwork needed to run its dryer properly. The maximum length of the exhaust system depends upon the type of duct, the number of elbows, and the type of exhaust hood used. Figure 20-8 illustrates a typical dryer exhaust installation.

FIGURE 20-8 Typical dryer exhaust installation.

The following guide is recommended for the exhausting of a dryer:

• Keep the duct length as short as possible.

• Keep the number of elbows to a minimum to minimize the air resistance.

• Never reduce the diameter of round ductwork below 4 inches.

• Install all exhaust hoods at least 12 inches above ground level.

• The exhaust duct and exhaust hood should be inspected periodically and cleaned, if necessary.

• All duct joints should be taped. Never use screws to join the duct joints together. Screws protruding into the duct will cause lint buildup, and this will eventually clog the duct.

• Never exhaust the dryer into any wall, ceiling, attic, or under a building.

• Accumulated lint could become a fire hazard, and moisture could cause damage.

• If the exhaust duct is adjacent to an air conditioning duct, the exhaust duct must be insulated to prevent moisture buildup.

Exhaust Ducting

The more that the dryer is used, the more frequently the exhaust ducts and vent hood must be inspected to prevent duct blockages and lint fires. The exhaust ducting and vent hood must be cleaned at least once a year for peak performance in drying.

When installing ductwork, separate all turns by at least 4 feet of straight duct, including the distance between the last turn and the dampened wall hood. If a turn is 45° or less, it can be ignored in figuring out duct distance. If you have two 45° turns, count it as one 90° turn. Also, each turn over 45° should be counted as one 90° turn (Figures 20-9, 20-10, 20-11, 20-12, and 20-13.

FIGURE 20-9 Recommended maximum length exhaust duct and hood for a direct drive blower in a dryer (one drive motor).

FIGURE 20-10 Recommended maximum length rigid exhaust duct and hood for a dryer with a separate drive motor for the blower assembly.

FIGURE 20-11 Recommended maximum length for flexible metal exhaust duct for a dryer with a separate drive motor for the blower assembly.

FIGURE 20-12 Make sure that the male fittings are installed in the correct direction.

FIGURE 20-13 Some examples of correct and incorrect exhaust duct installations.

When sealing the joints of the exhaust ducts with duct tape, the male end of each section of duct must point away from the dryer to prevent lint buildup. Also, never use screws to connect the ducts together; this will cause lint buildup. Any ductwork that runs through an unheated area or is near air conditioning must be insulated to prevent condensation and lint buildup.

SAFETY NOTE All exhaust ductwork must exhaust to the outside of a building to prevent lint buildup and fire. Do not terminate exhaust ductwork in a chimney, any gas vent, under enclosed floor (crawl space), common duct with a kitchen exhaust, or into an attic because the lint accumulation will cause a fire. Finally, never block incoming or exhausted air supplies; this will cause the dryer to run inefficiently and may cause a fire.

Step-by-Step Troubleshooting by Symptom Diagnosis

In the course of servicing an appliance, don’t overlook the simple things that might be causing the problem. Step-by-step troubleshooting by symptom diagnosis is based on diagnosing malfunctions, with possible causes arranged into categories relating to the operation of the dryer. This section is intended only to serve as a checklist to aid you in diagnosing a problem. Look at the symptom that best describes the problem that you are experiencing with the dryer, and then correct the problem.

Dryer Will Not Run

• Do you have the correct voltage at the dryer?

• Test the door switch for continuity of the switch contacts.

• Test for continuity of the motor windings. Also check for a grounded motor.

• Test the timer for continuity of the switch contacts.

• Test the “push to start” switch for continuity of the switch contacts.

• Check for broken or loose wiring. Also check the wire terminal connections that connect to the different components.

• For electronic control models, check for an error code. Check the electronic control board.

No Heat

• Do you have the correct voltage? The motor in a dryer runs on 120 volts. The heating element works on 240 volts; compact models run on 120/240 volts. Check voltage at the wall receptacle. Also check the nameplate voltage rating for the model that you are working on.

• Check for any in-line fuses that might have blown. Refer to the wiring diagram, located on the rear of the dryer or behind the console panel.

• Are the thermostats functioning properly?

• Test the timer for continuity of the switch contacts.

• Test for continuity of the motor windings. Also test for a grounded motor.

• Test the heating element for continuity.

• Test the temperature selector switch for continuity.

• Check for broken or loose wiring.

• Check the exhaust vent duct system.

• For electronic control models, check for an error code.

Drum Will Not Rotate

• Check the drive belt. Is it broken or worn?

• Check the idler pulley. Is the pulley seized up?

• Check the drum support bearings. Be sure that they rotate freely.

• Is the dryer overloaded with clothing?

• Check for foreign objects that might be lodged between the drum and the bulkheads.

• For electronic control models, check for an error code.

Dryer Is Noisy

• Check for loose components. Is everything secure and in its proper place?

• Check the idler pulley. Lint buildup can cause the idler pulley shaft to squeak.

• Check the drive belt. Is the belt partially torn?

• Check the drive motor. Is the pulley secured to the shaft? Also check the fan assembly. Is it loose?

• Check for lint or foreign objects lodged between the drum and the bulkheads.

• Check the front and rear bearings.

• Check the blower assembly. Be sure that the blower wheel is tight on the motor shaft end.

• Is the dryer level?

Dryer Runs and Heats, but the Clothes Won’t Dry

• Check for a defective thermostat. Use a thermometer to check the duct temperatures during the cycling of the dryer.

• Check for a loose pulley or blower wheel. Inspect and tighten the blower wheel.

• Check for restricted air flow in the dryer.

• Check the exhaust vent duct system.

• For electronic control models, check for an error code.

Clothes Too Hot or Fabric Damage

• Check the exhaust system for restrictions.

• Check for air leaks in the ductwork and the front and rear seals on the drum.

• Check the thermostats.

• Check the temperature setting with the customer.

• Check the door latch and strike.

• Inspect the interior of the drum for any foreign objects protruding into it.

Common Drying Problems

The drying of clothes can be affected by several factors:

• Clogged lint screen.

• Exhaust duct too long, collapsed, or crimped.

• Dryer air is exhausted into the area where the dryer is located. For example, the dryer is located inside a closet and operating with the closet door closed.

• Overloading of clothing in the dryer.

• Dryer is located in an area where the temperature is below 45 degrees Fahrenheit.

• Laundry washed in cold water will take slightly longer to dry.

• The moisture content of certain clothes. Towels and denim retain more moisture, for example.

• Wrong spin speed selected for the type of laundry being washed. For example, towels, denim, blankets, small rugs, etc. use the normal wash setting to extract most of the water from the laundry. If there is an extra option for high-speed spin it should also be selected to extract as much water as possible from the laundry. The drying cycle will be increased greatly if the permanent press cycle or the gentle cycle is selected for these items.

• Electric supply is less than what is needed to operate the dryer efficiently.

• Load type (towels, bedspreads, jeans, etc.)

All of these must be taken into account when diagnosing a complaint of clothes not drying properly.

Lint

Lint consists of fibers that have broken away from the fabric. It can collect inside the dryer cabinet and base and create a fire hazard. This lint should be removed every one to two years by cleaning it out. Some lint can also collect in the door opening, the drum, the heater assembly, the blower assembly, and the duct assembly. This accumulation of lint should be removed periodically when performing maintenance on the dryer; otherwise, it could create problems with the future use of the dryer.

The lint screen should be cleaned every time the dryer is used. The duct system that exhausts the air to the outside of the dwelling should also be cleaned out every one to two years.

Shrinkage

Shrinkage is caused by overdrying and by the type of fabric being dried. To reduce the shrinking of cotton and rayon knits, it is recommended that the user remove them from the dryer while the clothing is still damp and lay them on a flat surface to air-dry

Also, you might suggest that the user set the heat setting on a lower setting. Before drying any synthetic clothing in a dryer, the user should read the label on the garment for the proper drying instructions and for the proper heat selection. The user should also read the use and care manual for the proper instructions when operating the dryer.

Stains

Greasy-looking stains are often caused by:

• Fabric softener that is designed for use in the dryer.

• Fabric softener that was undiluted when the clothes were washed.

• Not enough detergent being used in the wash. This will cause the soil in the water to stick to the outer tub and to return to the next load being washed.

• Drying of clothing that already has a stain on it.

Brown stains on the clothing are often caused by:

• Fabric softener that is designed for use in the dryer.

• Leaving the wash in the washer tub after the cycle is completed.

• Leaving the wet clothing in the dryer for an extended amount of time.

• A leaking transmission seal.

Static Electricity

Static electricity in the clothes is caused by overdrying them. To reduce this condition, you must instruct the user to reduce the amount of time the clothes are to be dried and to use a lower temperature setting. Static electricity in synthetics is normal. To reduce this condition, use a liquid fabric softener in the wash cycle or use a fabric softener that is designed for use in the dryer.

Wrinkling

Wrinkling of the clothes is often caused by:

• Not using the permanent press cycle, which has a cooling-down period during which the heating element is not on.

• Clothing not removed from the dryer after it has completed the cycle.

• Overloading the dryer. The clothes need room to tumble freely without getting tangled.

• The quality of the permanent press material in the garment might be poor.

• On some models that have steam, check the water supply, water valve, and steam port.

Electric Dryer Maintenance

Automatic dryers must be cleaned periodically. The excess lint must be removed to prevent the possibility of a fire and the possibility of the dryer not functioning properly. Most models have a service panel on the front of the dryer for accessibility. The outside of the cabinet should be wiped with a damp cloth. It is recommended that the components be inspected for wear and tear; if repairs are needed, they should be made as soon as possible.

Repair Procedures

Each repair procedure is a complete inspection and repair process for a single dryer component, containing the information you need to test a component that might be faulty and to replace it, if necessary.

Any person who cannot use basic tools should not attempt to install, maintain, or repair any electric dryer. Any improper installation, preventative maintenance, or repairs will create a risk of personal injury, as well as property damage. Call the service manager if installation, preventative maintenance, or the repair procedure is not fully understood.

Dryer Timer

The dryer timer is an electromechanical component controlled by a synchronous motor in incremental advances. It controls and sequences the numerous steps and functions involved in each cycle.

The typical complaints associated with the dryer timer are:

• The dryer will not run at all.

• The clothes are not drying.

• The dryer will not stop at the end of the cycle.

• The timer will not advance through the cycle.

To handle these problems, perform the following steps:

1. Verify the complaint. Verify the complaint by operating the dryer through its cycles. Before you change the timer, check the other components controlled by the timer. If the dryer will not power up, locate the technical data sheet behind the control panel or for diagnostics information. On some models you will need the actual service manual for the model you are working on to properly diagnose the dryer.

2. Check for external factors. You must check for external factors not associated with the appliance. Is the appliance installed properly? Does the appliance have the correct voltage? The voltage at the receptacle is between 198 volts and 264 volts during a load on the circuit (see Chapter 6).

3. Disconnect the electricity. Before working on the dryer, disconnect the electricity. This can be done by pulling the plug from the electrical outlet. Or disconnect the electricity at the fuse panel or at the circuit breaker panel. Turn off the electricity.

WARNING Some diagnostic tests will require you to test the components with the power turned on. When you disassemble the control panel, you can position it in such a way that the wiring will not make contact with metal. This act will allow you to test the components without electrical mishaps.

4. Remove the console panel to gain access. To gain access to the timer, remove the screws that secure the console to the top of the dryer (Figure 20-14). On other models, to gain access, remove the back panel behind the console.

FIGURE 20-14 To gain access to the component, remove the screws. Rest the console panel on its face to gain access to the component.

5. Test the timer. There are two ways to check the timer:

• Connect a 120-volt fused service cord to the timer motor to see if the timer motor is operating (Figure 20-15). Connect the ground wire of the 120-volt fused service cord to the console ground. Be cautious when working with live wires. Avoid getting shocked. The timer motor operates on 120 volts. If the motor does not operate, replace the timer. If the timer motor runs but does not advance the cams, the timer has internal defects and should be replaced.

FIGURE 20-15 The test cord attached to the timer motor leads.

• Set the ohmmeter range to R x 100, disconnect the timer motor leads, and check for resistance (Figure 20-16). The meter should read between 2000 and 3000 ohms. Next, test the timer switch contacts with the wiring diagram’s configuration for the affected cycle. Place the meter probe on each terminal being tested, and turn the timer knob. If the switch contact is good, your meter will show continuity.

FIGURE 20-16 Checking for continuity between the timer motor and the switch contacts.

6. Remove the timer. To remove the timer, pull the timer knob from the timer stem; then remove the timer mounting screws. Remove the wire lead terminals from the timer. Mark the wires as to their location on the timer. Some timers have a quick disconnect, instead of individual wires, which makes it easier to remove the timer wires (Figure 20-17).

FIGURE 20-17 Remove the timer dial. Then remove the timer mounting screws, and lift the timer off the mounting bracket.

7. Install a new timer. To install a new timer, just reverse the disassembly procedure, and reassemble. Replace the wires on the timer. Reinstall the console panel, and restore the electricity to the dryer. Test the dryer for proper operation. Make sure to take the dryer out of the service test mode when the repair is completed.

Electronic Control Board and User Interface Controls

On some models the electronic control board and user interface controls replace the electromechanical timer and rotary selection switches.

The typical complaints associated with the electronic control board or the user interface controls are:

• The dryer won’t run or power up.

• Unable to program the dryer.

• The display board will not display anything.

• One or more key pads will not accept commands.

• Unusual display readouts.

• Unusual display readouts and/or error codes.

To prevent electrostatic discharge (ESD) from damaging expensive electronic components, follow the steps in Chapters 6 and 11.

To handle these problems, perform the following steps:

1. Verify the complaint. Verify the complaint by operating the dryer. Turn off the electricity to the appliance and wait for two minutes before turning it back on. If a fault code appears, look up the code. If the dryer will not power up, locate the technical data sheet behind the control panel or for diagnostics information. On some models you will need the actual service manual for the model you are working on to properly diagnose the dryer. The service manual will assist you in properly placing the dryer in the service test mode for testing the dryer functions.

2. Check for external factors. You must check for external factors not associated with the appliance. Does the appliance have the correct voltage? The voltage at the receptacle is between 198 volts and 264 volts during a load on the circuit (see Chapter 6).

3. Disconnect the electricity. Before working on the dryer, disconnect the electricity. This can be done by pulling the plug out of the wall receptacle. Or disconnect the electricity at the fuse panel or circuit breaker panel. Turn off the electricity.

WARNING Some diagnostic tests will require you to test the components with the power turned on. When you disassemble the control panel, you can position the panel in such a way so that the wiring will not make contact with metal. This will allow you to test the components without electrical mishaps.

4. Remove the console panel to gain access. Begin by removing the screws from the dryer top (for front-loading models only) to gain access to the electronic control board. Remove the console panel screws to gain access to the user interface controls (Figure 20-18). On top-loading models, the console will roll upwards or toward you after you remove the console screws.

FIGURE 20-18 An exploded view of the electronic controls in a front-loading dryer.

5. Test the electronic control board and user interface controls. If you are able to run the dryer diagnostic test mode, check the different functions of the dryer. Use the technical data sheet for the model you are servicing to locate the test points from the wiring schematic. Check all wiring connections and wiring. Using the technical data sheet, test the electronic control or user interface controls, input voltages, and output voltages. On some models, fuses are soldered to the printed circuit board (PCB). These fuses must be tested first before condemning the component.

6. Remove the electronic control board and user interface controls. To remove the defective component, remove the screws that secure the board to the control panel or dryer frame. Disconnect the connectors from the electronic control board or user interface control.

7. Install the new component. To install a new electronic control board or user interface control, read the parts data sheet that comes with the part for the proper installation process, and just reverse the disassembly procedure and reassemble. Reinstall the console panel, and restore the electricity to the dryer. Make sure that the dryer in not in the service mode. Test the dryer operation. Make sure to take the dryer out of the service test mode when the repair is completed.

Dryer Motor

The dryer motor on most models is a dual-shaft, single-speed, ¼-horsepower, 1725-rpm motor with an automatic thermal reset protector. One side of the motor shaft is threaded to hold the blower wheel, and the opposite end of the shaft holds the belt pulley, which is pressed onto the shaft. Inside the motor is a centrifugal switch, which serves three purposes. It disengages the motor start winding when the motor reaches 75 percent of its rated speed, engages the run winding, and closes the circuit for the heater element. On other models, there are dual motors (Figure 20-2): one is dedicated to the drum and the other is dedicated to the blower assembly. The purpose of the dedicated motor for the blower assembly is to be able to alter the blower wheel speed whenever necessary to optimize air flow within the dryer.

The typical complaints associated with motor failure are:

• Fuse is blown or the circuit breaker trips.

• Motor will not start; it only hums.

• The dryer will not run.

To handle these problems, perform the following steps:

1. Verify the complaint. Verify the complaint by operating the dryer through its cycles. Listen carefully, and you will hear if there are any unusual noises or if the circuit breaker trips. On electronic models, turn off the electricity to the appliance and wait for two minutes before turning it back on. If a fault code appears, look up the code. If the dryer will not power up, locate the technical data sheet behind the control panel or for diagnostics information. On some models you will need the actual service manual for the model you are working on to properly diagnose the dryer. The service manual will assist you in properly placing the dryer in the service test mode for testing the dryer functions.

4. Gain access to the motor. In order to gain access to the motor, the top must be raised (Figure 20-19) by removing the screws from the lint screen slot. Insert a putty knife about two inches from each corner; then disengage the retaining clips and lift the top. On some models, the top is held down with screws (see inset in Figure 20-19). Remove the screws and lift the top. Now the front panel of the dryer must be removed (Figure 20-20). To remove the top panel, insert a putty knife and disengage the retaining clip (Figure 20-20a).

FIGURE 20-19 Insert a putty knife to disengage the retaining clips that hold the top down. Don't forget to remove the two screws under the lint screen cover. On some models, remove the screws from underneath the top (see insert).

FIGURE 20-20 Remove the top panel. Remove the screws from the lower front panel. Remove the screws from the upper front panel. Remember to remove the door switch wires.

On some models, the top panel is held in place with two screws. As Figure 20-20b shows, remove the screws that hold the lower part of the front panel in place. Next, remove the screws that hold the upper part of the front panel in place (Figure 20-20c), and then disconnect the door switch wires (label them). With the front panel out of the way, you can now disconnect the drive belt (Figure 20-21). Push on the idler pulley to release the tension from the drive belt, and remove the belt from the motor pulley. Grab the drum and remove it from the cabinet (Figure 20-22). On some models, you will have to remove the back panel because the drum comes out through the rear of the cabinet.

FIGURE 20-21 Push the idler pulley assembly toward the drive motor pulley to release the belt tension. Then disconnect the drive belt from the idler pulley and drive motor pulley.

FIGURE 20-22 Remove the drum from the dryer cavity.

5. Disconnect the motor wire leads. Disconnect the motor wire leads from the wiring harness. Set the ohmmeter on R x 1. Figure 20-23 illustrates testing the motor windings and the centrifugal switch for continuity. When testing for resistance on the motor, test from the common wire lead to the run winding. Then test for resistance from the common wire lead to the start winding. Next, test for resistance from the start winding to the run winding. To test for a grounded winding in the motor, take the ohmmeter probes and test from each motor wire lead terminal to the motor housing. The ohmmeter will indicate continuity if the windings are grounded. If the ohmmeter reading shows no resistance between the motor windings, then replace the motor. If the motor checks out okay, then check the timer.

FIGURE 20-23 Test the centrifugal switch and drive motor windings.

6. Remove the motor. To remove this type of motor, you must first disconnect the blower assembly by holding the motor shaft stationary and then turning the blower wheel to remove it from the rear of the motor shaft (Figure 20-24). Then remove the spring clamps that hold the motor in the motor bracket (Figure 20-25). On some models, the motor pulley must be removed (new motors come without the pulley attached) by loosening the allen set screw.

FIGURE 20-24 Disconnect the blower assembly from the drive motor shaft.

FIGURE 20-25 Hold the motor and remove the spring clamps.

7. Install the new motor. To install the new motor (Figure 20-26), just reverse the disassembly procedure, and reassemble. Then reassemble the dryer in the reverse order of its disassembly. Restore the electricity to the dryer and test the motor. Make sure to take the dryer out of the service test mode when the repair is completed.

FIGURE 20-26 Place the motor in the cradle and position it to fit into the slots properly.

Drive Belt

The drive belt extends from the motor pulley, past the idler pulley, and around the perimeter of the dryer drum. The tension on the belt is maintained by the idler pulley and driven by a pulley attached to the one end of the motor shaft.

The typical complaints associated with belt failure are:

• The drum will not turn.

• Dryer motor spins freely.

• It smells like something is burning.

To handle these problems, perform the following steps:

1. Verify the complaint. Verify the complaint by operating the dryer through its cycles. Listen carefully and you will hear if there are any unusual noises. Then, with the door open, press the door switch and start the dryer. The drum should rotate. On electronic models, turn off the electricity to the appliance and wait for two minutes before turning it back on. If a fault code appears, look up the code. If the dryer will not power up, locate the technical data sheet behind the control panel or for diagnostics information. On some models you will need the actual service manual for the model you are working on to properly diagnose the dryer. The service manual will assist you in properly placing the dryer in the service test mode for testing the dryer functions.

4. Gain access to the drive belt. To gain access to the drive belt, the top must be raised (see Figure 20-19) by removing the screws from the lint screen slot. Then insert a putty knife about two inches from each corner, disengage the retaining clips, and lift the top. On some models, the top is held down with screws (see the inset in Figure 20-19). Remove the screws and lift the top. Now the front panel of the dryer must be removed (see Figure 20-20). To remove the top panel, insert a putty knife and disengage the retaining clip (see Figure 20-20a). As shown in Figure 20-20b, remove the screws that hold the lower part of the front panel in place. Next, remove the screws that hold the upper part of the front panel in place (see Figure 20-20c), and then disconnect the door switch wires.

5. Remove the drive belt. To remove the drive belt on this type of dryer, you can disconnect the belt (see Figure 20-21). Push on the idler pulley to release the tension from the drive belt. Now remove the belt from the motor pulley and from around the drum (Figure 20-27). If the drive belt is broken, just remove the belt.

FIGURE 20-27 Removing the drive belt from around the drum.

6. Install a new drive belt. To install the new drive belt, just reverse the disassembly procedure, and reassemble. Then reassemble the dryer in the reverse order of its disassembly. Restore the electricity to the dryer and test. Make sure to take the dryer out of the service test mode when the repair is completed.

Heater Element

The heater assembly on some models is located behind the dryer drum (Figure 20-28), while on other models the heater assembly is located in the back of the dryer, and on other models the heater assembly is located on the bottom of the dryer (Figure 20-29).

FIGURE 20-28 Dual-heater element mounted on the rear of the dryer.

FIGURE 20-29 Heating element located on the bottom of the dryer.

The typical complaints associated with heater failure are:

• The dryer will not dry the clothes properly.

• There is no heat at all when a heat cycle is selected.

• On electronic models, an error code appears.

To handle these problems, perform the following steps:

1. Verify the complaint. Verify the complaint by operating the dryer through its cycles. Then open the dryer door, and place your hand inside to see if it is warm in the drum. On electronic models, turn off the electricity to the appliance and wait for two minutes before turning it back on. If a fault code appears, look up the code. If the dryer will not power up, locate the technical data sheet behind the control panel or for diagnostics information. On some models you will need the actual service manual for the model you are working on to properly diagnose the dryer. The service manual will assist you in properly placing the dryer in the service test mode for testing the dryer functions.

2. Check for external factors. You must check for external factors not associated with the appliance. Is the appliance installed properly? Is the exhaust vent clogged? Does the appliance have the correct voltage? The voltage at the receptacle is between 198 volts and 264 volts during a load on the circuit (see Chapter 6).

NOTE The dryer motor runs on 120 volts, but the heater works on 240 volts. Check the fuses or the circuit breakers in the home.

4. Gain access to the heater assembly. You must gain access to the heater assembly through the back. Remove the exhaust duct from the dryer. Then remove the screws from the back panel (Figure 20-30).

FIGURE 20-30 Remove the screws that hold the back panel in place.

5. Test the heater element. To test the heater element, set the ohmmeter on R x 1. Remove the wires from the heater (Figure 20-31), and test for continuity. If it checks out okay, check the thermostats.

FIGURE 20-31 Test the heater element for continuity.

6. Remove the heater element. To remove the heater in this type of dryer, you must first remove the screw and the bracket that holds the heater box in place. It is located on top of the heater box. You can gain access through the back of the dryer or lift the top and reach in near the back bulkhead. Then slide the heater box up, and pull it away at the bottom (Figure 20-32). With the heater box out of the dryer, remove the screw that holds the heater element in place (Figure 20-33). Pull the heater element out of the heater box.

FIGURE 20-32 Remove the heater box.

FIGURE 20-33 Remove the heater coil from the heater box.

7. Install new heater element. To install the new heater element, just reverse the disassembly procedure, and reassemble. Then reinstall the back panel. Restore the electricity to the dryer and test it. Make sure to take the dryer out of the service test mode when the repair is completed.

Door Switch

The door switch is a normally open switch wired in series with the dryer motor. When the dryer door is closed, the door switch contacts will close completing the circuit through the run winding of the drive motor.

The typical complaints associated with switch failure are:

• Dryer will not operate at all.

• Dryer light does not work when the door is open.

To handle these problems, perform the following steps:

1. Verify the complaint. Verify the complaint by operating the dryer through its cycles. Open the door to see if the light is working. On electronic models, turn off the electricity to the appliance and wait for two minutes before turning it back on. If a fault code appears, look up the code. If the dryer will not power up, locate the technical data sheet behind the control panel or for diagnostics information. On some models you will need the actual service manual for the model you are working on to properly diagnose the dryer. The service manual will assist you in properly placing the dryer in the service test mode for testing the dryer functions.

2. Check for external factors. You must check for external factors not associated with the appliance. Is the appliance installed properly? Does the dryer have the correct voltage supply? The voltage at the receptacle is between 198 volts and 264 volts during a load on the circuit (see Chapter 6).

4. Gain access to the door switch. You must gain access to the door switch. On this model, the top must be raised (see Figure 20-19) by removing the screws from the lint screen slot. Then insert a putty knife about two inches from each corner, disengage the retaining clips, and lift the top. On some models, the top is held down with screws (see the inset in Figure 20-19). Remove the screws and lift the top.

5. Test the door switch. The door switch is located in one of the upper corners of the inside of the front panel (Figure 20-34a). Once you have located the door switch, disconnect the wires from the terminals. Set the ohmmeter on R × 1, attach the probes of the ohmmeter to the terminals of the door switch, and then close the door. With the door closed, there should be continuity. With the door open, the ohmmeter should not show continuity. Some dryer models have a light inside the drum. This light circuit is also part of the door switch circuitry. Three terminals are located on the door switch. Take your ohmmeter probe and place it on the common terminal of the door switch. To locate the common terminal, read the wiring diagram. It will indicate which terminal is the common, which is the light, and which is for the motor circuit. Take your probe and place it on the switch terminal (the light circuit); then close the dryer door. The reading should indicate no continuity. Now open the dryer door—you should have a continuity reading on the meter.

6. Remove the door switch. To remove the lever-type door switch (Figure 20-34b); remove the screws that hold the switch in place. Now lift the switch out from behind the front panel. To remove the cylindrical type of door switch (Figure 20-34c), squeeze the retaining clips on the back side of the front panel, and pull out the switch. To remove the hinge type of door switch (Figure 20-34d), the front panel must be removed. Next, remove the screws that hold the switch assembly in place.

FIGURE 20-34 (a) Test the door switch for continuity. (b) Remove the screws that secure the door switch. (c) Removing a cylindrical door switch. (d) Removing a hinge-mounted door switch.

7. Install the new door switch. To install the new door switch, reverse the disassembly procedure, and reassemble. Reassemble the dryer, and install the wires on the new switch terminals. Plug in the dryer and test it. Make sure to take the dryer out of the service test mode when the repair is completed.

Thermostat

Thermostats can be mounted on the heater assembly (Figure 20-2 and Figure 20-29) and/or on the blower assembly (Figures 20-2 and 20-35), or in the inlet filter screen (Figure 20-37). The thermostats monitor the air temperatures within the dryer drum, exhaust vent, and the incoming air supply. The thermostats are bimetal switches that are automatic reset, one-time use, or manual reset.

FIGURE 20-35 The thermostat is mounted on the exhaust vent pipe along with the thermal fuse.

The typical complaints associated with thermostat failure are:

• The clothes are not drying.

• The dryer will not shut off.

• The dryer will not heat at all.

• The drying temperature is too high.

• Moisture retention (of fabrics) is unsatisfactory.

• On electronic models, an error code appears.

To handle these problems, perform the following steps:

1. Verify the complaint. Verify the complaint by operating the dryer through its cycles. On electronic models, turn off the electricity to the appliance and wait for two minutes before turning it back on. If a fault code appears, look up the code. If the dryer will not power up, locate the technical data sheet behind the control panel or for diagnostics information. On some models you will need the actual service manual for the model you are working on to properly diagnose the dryer. The service manual will assist you in properly placing the dryer in the service test mode for testing the dryer functions.

4. Gain access to the thermostat. You must gain access to the thermostat through the back on this model. Remove the screws from the back panel (see Figure 20-30).

5. Test the thermostat. To test the thermostat for continuity, remove the wires from the thermostat terminals. With a continuity tester or an ohmmeter, test the thermostat for continuity (Figure 20-36). Do this to all of the thermostats in the dryer. On some models, the thermostats might be located on the heater housing, behind the drum, or in the lint screen opening (Figure 20-37). If they all check out okay, then reassemble the dryer and test for temperature operation.

FIGURE 20-36 Use a continuity tester to check the thermostats.

FIGURE 20-37 The location of thermostats on some models.

NOTE Do not reinstall the back panel at this point. Take a piece of paper and write down the temperature ratings of the thermostats. These ratings are printed on the thermostats (L140, L290, etc.) or on the wiring schematic. To test for temperature operation, you will need a voltmeter and a temperature tester.

First, set up the instruments for testing the thermostatic operation. Take the temperature tester thermocouple lead and insert it between the thermostat mounting ear (Figure 20-38) and the plate against which it mounts. Then connect the voltmeter probes across the thermostat terminals. Use alligator clips attached to the probe tips. This will allow you freedom of movement. Do not disconnect the wires from the thermostat. Set the voltmeter range to AC voltage and the selector switch on 300 volts. Remember: If there is more than one thermostat (in series with other thermostats), the thermostats not under test must be electrically isolated and jumped out with an insulated jumper wire with alligator clips attached. Review the wiring schematic to determine which wires to remove and which ones to isolate and jump out. With the test meters in place, you are now ready to remove the exhaust vent duct from the dryer. Seal off 75 percent of the exhaust opening from the dryer (Figure 20-39). This will simulate a load of clothing in the dryer. On some models, you do not have to block off the exhaust opening. Check the technical data sheet or the service manual for the model you are servicing.

FIGURE 20-38 Insert the thermocouple lead under the thermostat ear.

FIGURE 20-39 Block (or tape) 75 percent of the dryer exhaust to simulate a load.

Restore the electricity to the dryer. This test requires that the electricity be turned on for its duration. Always be cautious when working with live wires. Avoid getting shocked. Set the controls on the dryer to operate at a high heat. Turn on the dryer and let it cycle. When the voltmeter is reading voltage, the thermostat has opened. When there is no voltage reading on the voltmeter, the thermostat is closed. As the dryer is cycling via the thermostat, record the temperature.

The thermostat should open at the preset temperature listed on the thermostat. Table 20-1 illustrates the types of thermostats, along with their opening and closing temperature settings. The temperature range of the thermostat should be within ±10 percent of the printed setting. If not, replace the thermostat.

TABLE 20-1 Thermostat Opening and Closing Temperatures

CAUTION Turn off the electricity before replacing any parts of the dryer.

On some models, the thermostat will have four wires attached to it. Two wires are for the bimetal switch contacts and the other two wires are for the bias heater. The purpose of the bias heater is to apply a small amount of heat to the bimetal switch contacts when the timer or fabric temperature switch is set to a lower temperature setting. This will allow the bimetal switch contacts to open up sooner to maintain a lower drum temperature. To test the bias heater, remove the wires from the thermostat, set your multimeter to the ohms scale, and test across the bias heater terminals. The resistance of the bias heater should be between 7000 and 28,000 ohms.

6. Replace the thermostat. Remove the screws that hold the thermostat in place. Replace the thermostat with an exact replacement with the same temperature rating. Reconnect the wires to their correct terminal positions. Then reverse the disassembly procedure to reassemble the dryer, and test the thermostat.

7. Test the new thermostats. To test the new thermostats, repeat step 5. Make sure to take the dryer out of the service test mode when the repair is completed.

Thermistor

The thermistor (Figure 20-2) monitors the incoming and outgoing air temperatures and relays that information back to the electronic control board.

The typical complaints associated with thermistor failure are:

• The clothes are not drying.

• The dryer will not shut off.

• The dryer will not heat at all.

• The drying temperature is too high.

• Moisture retention (of fabrics) is unsatisfactory.

• On electronic models, an error code appears.

To handle these problems, perform the following steps:

4. Gain access to the thermistor. To gain access to the thermistor on this model you will have to remove the top panel, control panel (Figure 20-40), front panel (Figure 20-41), and the dryer drum (Figure 20-2).

FIGURE 20-40 After removing the control panel, place it on a table so as not to damage the electronics inside the panel.

FIGURE 20-41 A top view of the dryer with the front panel being removed.

5. Test the thermistor. To test the thermistor for resistance, remove the wires from the thermistor terminals. Set your multimeter on the ohms scale and place the test leads on the thermistor terminals. Match the reading to the technical data sheet or the service manual values. If you are reading an open or infinity, replace the thermistor. Another way to test the thermistor is by placing the dryer into the service mode. On some models, the thermistor might be located on the heater housing, behind the drum, or in the lint screen opening (Figures 20-2 and 20-37). If they all check out okay, then reassemble the dryer and test for temperature operation.

6. Replace the thermistor. Remove the screws that hold the thermistor in place. Replace the thermistor with an exact replacement with the same temperature rating. Reconnect the wires to their correct terminal positions. Then reverse the disassembly procedure to reassemble the dryer, and test the thermistor.

7. Test the new thermistor. To test the new thermistor, repeat step 5. Make sure to take the dryer out of the service test mode when the repair is completed.

Start Switch

The start switch is a rotary or push button momentary contact switch used to start the dryer and to energize the start winding in the drive motor. This switch is located in the control panel on the dryer. The dryer door must be closed for the dryer to operate. If and when the dryer door is opened, the start switch must be turned on to restart the dryer operation.

The typical complaint associated with the start switch is that the dryer will not start. To handle this problem, perform the following steps:

1. Verify the complaint. Verify the complaint by operating the dryer. Before you change the start switch, check the other components that are in the start circuit. On electronic models, turn off the electricity to the appliance and wait for two minutes before turning it back on. If a fault code appears, look up the code. If the dryer will not power up, locate the technical data sheet behind the control panel for the diagnostics information. On some models you will need the actual service manual for the model you are working on to properly diagnose the dryer. The service manual will assist you in properly placing the dryer in the service test mode for testing the dryer functions.

2. Check for external factors. You must check for external factors not associated with the appliance. Is the appliance installed properly? Does it have the correct voltage? The voltage at the receptacle is between 198 volts and 264 volts during a load on the circuit (see Chapter 6). Check the fuses or circuit breaker.

4. Remove the console panel to gain access. Begin by removing the console panel to gain access to the start switch. With this type of dryer, remove the screws from the console (see Figure 20-14a). On some models, the console will be able to lie flat (see Figure 20-14b).

5. Test the start switch. Remove the wires from the start switch terminals. Set the ohmmeter on R x 1. Begin testing the start switch for continuity by placing one probe of the ohmmeter on the common terminal (C) of the switch; then connect the other probe to the normally open (NO) terminal. There should be no continuity. With the ohmmeter probes attached to the switch, press the start switch button. You should have continuity (Figure 20-42). If the switch fails the test, replace it.

FIGURE 20-42 Test the continuity of the switch contacts on a start switch.

6. Remove the start switch. To remove the start switch, pull the knob off the switch stem, remove the start switch mounting screws, and remove the switch.

7. Install a new start switch. To install a new start switch, just reverse the disassembly procedure, and reassemble. Replace the wires on the switch. Reinstall the console panel, and restore the electricity to the dryer. Test the dryer operation.

Drum Roller

The drum roller is located on the rear bulkhead of the dryer. Its main purpose is to support the dryer drum and assist with easy drum rotation.

The typical complaints associated with the drum roller are:

• Dryer is very noisy when operating.

• Dryer has a burning smell.

• The dryer drum is hard to turn manually.

To handle these problems, perform the following steps:

4. Gain access to the drum roller. To gain access to the drum roller, the top must be raised (see Figure 20-19) by removing the screws from the lint screen slot. Then insert a putty knife about two inches from each corner to disengage the retaining clips, and lift the top. On some models, the top is held down with screws (see the inset in Figure 20-19). Remove the screws and lift the top. Now the front panel of the dryer must be removed (see Figure 20-20). To remove the top panel, insert a putty knife and disengage the retaining clip (see Figure 20-20a). As in Figure 20-20b, remove the screws that hold the lower part of the front panel in place; then remove the screws that hold the upper part of the front panel in place (see Figure 20-20c). Disconnect the door switch wires.

5. Remove the drive belt and drum. To remove the drive belt and the drum on this type of dryer, you must first disconnect the belt (see Figure 20-21). Push on the idler pulley to release the tension from the drive belt. Remove the belt from the motor pulley and from around the drum (see Figure 20-27). Grab hold of the drum and remove it from the cabinet (see Figure 20-22).

6. Remove the drum roller. Once the drum has been removed, the drum rollers, which are located on the rear bulkhead of this model (Figure 20-43), can then be removed. Take a pair of needle nose pliers and remove the tri-ring from the shaft. Then slide the roller off the shaft.

FIGURE 20-43 You must remove the tri-ring first in order to remove the drum roller.

7. Install a new drum roller. To install the new roller, clean the shaft and lubricate it with a small amount of oil. Slide the new drum roller onto the shaft, and reinstall the tri-ring. To reassemble the dryer, just reverse the disassembly procedure, and reassemble. Test the dryer for proper operation. Make sure to take the dryer out of the service test mode when the repair is completed.

Idler Pulley

The idler pulley assembly is positioned on the dryer chassis and inserted into a slot in the base located next to the drive motor; it maintains the proper tension on the drive belt and minimizes belt slippage.

The typical complaints associated with the idler pulley are:

• When dryer is running, you will hear a squealing noise.

• The dryer belt burns and might snap.

• The dryer drum will not turn.

To handle these problems, perform the following steps:

4. Gain access to the idler pulley. To gain access to the idler pulley, in this type of dryer, remove the top panel, insert a putty knife, and disengage the retaining clip (see Figure 20-20a).

5. Remove the idler pulley. To remove the idler pulley, you must first remove the drive belt. To disconnect the belt on this model (see Figure 20-21), push on the idler pulley to release the tension from the drive belt. Now remove the belt from the motor pulley and from around the idler pulley. If the drive belt is broken, just remove the belt. Next, lift the idler pulley up and out of the dryer (Figure 20-44). This type of idler pulley is replaced as a complete assembly. Another type of idler pulley (Figure 20-45a) has a tension spring. To remove this type of idler, you must first remove the tension spring (Figure 20-45b), and then lift the idler assembly out of the dryer. Inspect the pulley for wear. If it is worn, remove the screw from the axle, and pull the axle out (Figure 20-45c). On this type of idler pulley, only replace the worn-out part.

FIGURE 20-44 After removing the drive belt, lift the idler pulley off the base.

FIGURE 20-45 (a) This type of idler pulley uses a spring to hold tension against the drive belt. (b) Remove the spring and lift the idler assembly out of the dryer for inspection. (c) Remove the axle to replace the pulley.

6. Install the new idler pulley. To install the repaired idler pulley, just reverse the disassembly procedure, and reassemble it. Reassemble the dryer in the reverse order of its disassembly, and test it for proper operation. Make sure to take the dryer out of the service test mode when the repair is completed.

Temperature Selector Switch

The temperature selector switch is located in the console panel. This switch allows the consumer to select different temperature settings for drying.

The typical complaints associated with the temperature selector switch are:

• Inability to select a certain temperature setting.

• No heat.

• The switch is stuck.

To handle these problems, perform the following steps:

1. Verify the complaint. Verify the complaint by operating the dryer through its cycles. Before you change the temperature selector switch, check the other components controlled by this switch. On electronic models, turn off the electricity to the appliance and wait for two minutes before turning it back on. If a fault code appears, look up the code. If the dryer will not power up, locate the technical data sheet behind the control panel or for diagnostics information. On some models you will need the actual service manual for the model you are working on to properly diagnose the dryer. The service manual will assist you in properly placing the dryer in the service test mode for testing the dryer functions.

3. Disconnect the electricity. Before working on the dryer, disconnect the electricity to it. This can be done by pulling the plug from the electrical outlet. Or disconnect the electricity at the fuse panel or at the circuit breaker panel. Turn off the electricity.

4. Gain access to the temperature selector switch. To access the temperature selector switch, remove the console panel. On this type of dryer, remove the screws in the console (see Figure 20-14a). On some models, the console will be able to lie flat (see Figure 20-14b). On other models, your access is through the rear panel on the console.

5. Test the temperature selector switch. To test the temperature selector switch, locate the selector switch circuit on the wiring diagram. Identify the terminals that are regulating the temperature setting to be tested. Set the ohmmeter on the R x 1 scale. Next, place the ohmmeter probes on those terminals. Then select that temperature setting by either rotating the dial or by depressing the proper button on the switch (Figure 20-46). If the switch contacts are good, your meter will show continuity. Test all of the remaining temperature settings on the temperature selector switch. Remember to check the wiring diagram for the correct switch contact terminals (those that correspond to the setting that you are testing).

FIGURE 20-46 Test the temperature selector switch for continuity.

6. Remove the temperature selector switch. To remove the temperature selector switch, remove the screws that hold the switch to the console base, and remove the switch.

7. Install the new temperature selector switch. To install the new temperature selector switch, just reverse the disassembly procedure, and reassemble it. Then reattach the wires to the switch terminals according to the wiring diagram. Reassemble the console panel. Be sure when reassembling the console panel that the wires do not become pinched between the console panel and the top of the dryer. Make sure to take the dryer out of the service test mode when the repair is completed.

Belt Switch

The belt switch is located on the drive motor baseplate (Figure 20-47) and held in place with two Phillips-head screws. The belt switch is activated by the movement of the idler pulley assembly. If the belt breaks or comes off the pulley, the belt switch disconnects the power to the motor, shutting down the dryer.

FIGURE 20-47 The belt switch is a normally closed switch. When the belt breaks, the belt switch opens the circuit, shutting off the dryer motor.

The typical complaints associated with the idler pulley are:

• The dryer will not run.

• The clothes are wet.

4. Gain access to the belt switch. To gain access to the belt switch, in this type of dryer, remove the top panel, insert a putty knife, and disengage the retaining clip (see Figure 20-20a).

5. Remove the idler pulley. Before removing the belt switch you must first remove the idler pulley and drive belt. To disconnect the belt on this model (see Figure 20-21), push on the idler pulley to release the tension from the drive belt. Now remove the belt from the motor pulley and from around the idler pulley. If the drive belt is broken, just remove the belt. Next remove the two Phillips-head screws from the belt switch (Figure 20-47).

6. Test the belt switch. Remove the two wires from the belt switch. Place your multimeter test leads on the terminals and turn your meter to the ohms scale. When activating the belt switch, the meter reading will indicate continuity. When deactivating the belt switch, the meter reading will indicate an infinity reading. If the meter indicates infinity when the belt switch is activated and deactivated, replace the switch.

7. Install the new belt switch. To install the belt switch, just reverse the disassembly procedure, and reassemble it. Reassemble the dryer in the reverse order of its disassembly, and test it for proper operation. Make sure to take the dryer out of the service test mode when the repair is completed.

Diagnostic Charts

The following diagnostic flowcharts will help you to pinpoint the likely causes of dryer problems (Figures 20-48, 20-49, 20-50, 20-51, and 20-52).

FIGURE 20-48 The diagnostic flowchart: No heat, long dry time.

FIGURE 20-49 The diagnostic flowchart: No heat and the drum turns.

FIGURE 20-50 The diagnostic flowchart: The timer will not advance on auto-cycle.

FIGURE 20-51 The diagnostic flowchart: Dryer will not run.

FIGURE 20-52 The diagnostic flowchart: Wrinkles, shrinkage, and damaged clothing with all fabrics on all dried loads.

The wiring diagram in this chapter is only an example. You must refer to the wiring diagrams on the dryer that you are servicing. Figure 20-53 depicts an actual wiring schematic diagram and an actual pictorial electrical wiring diagram. Figure 20-54 depicts an actual ladder diagram. A ladder diagram is simpler and is usually easier to read. Figure 20-55 depicts a typical wiring diagram for a new-style front load dryer with electronic controls and two electric heating elements. Figure 20-56 depicts a typical wiring diagram for a standard electric dryer with a mechanical timer. Figure 20-57 depicts a typical wiring diagram for a new-style front load dryer with electronic controls and three electric heating elements.

FIGURE 20-53 The automatic dryer wiring diagram.

FIGURE 20-54 The automatic dryer ladder diagram.

FIGURE 20-55 A typical wiring diagram for a new-style front load dryer with electronic controls and two electric heating elements.

FIGURE 20-56 A typical wiring diagram for a standard electric dryer with a mechanical timer.

FIGURE 20-57 A typical wiring diagram for a new-style front load dryer with electronic controls and three electric heating elements.