5

CHAPTER

Basic Techniques

There are many different ways to diagnose a problem, but all of them use basically the same reasoning:

•  Where does the consumer think the malfunction is located within the appliance or air conditioner?

•  Where is the actual problem located within the appliance or air conditioner?

•  Are there any related problems with the appliance or air conditioner?

•  How can the problem with the appliance or air conditioner be solved?

For example, the consumer states that the dryer does not dry the clothes and believes that the heating element is bad. The actual problem might be a restricted exhaust vent, a clogged lint filter, bad heating elements, faulty operating thermostats or safety thermostat, or improper control settings.

When checking the dryer, you might notice that the control settings are set for air drying instead of heat drying. Thus the actual problem was that the control settings were not positioned correctly. The related problem is: “How did the control setting move to the air-dry position?” This leads to the question: “Does the consumer know how to operate the dryer?” To solve this problem, you will have to instruct the consumer in the proper operation of the dryer.

All appliances and air conditioners go through a certain sequence of events. Understanding the proper operation and this sequence as indicated in the use and care manual is beneficial when diagnosing the appliance or air conditioner.

Product Failure

Given the information about the product’s problem, information and diagnostic charts from this book, and the information you have read in the use and care manual, as the servicer you will be able to perform the following steps in sequence to diagnose and correct a malfunction. The basic steps to follow when diagnosing an appliance or air conditioner problem are:

1.  Verify the complaint. Ask the consumer what symptoms were caused by the problem with the appliance or air conditioner.

2.  Check for external factors. For example: is the appliance or air conditioner installed properly, does the product have the correct voltage, etc.?

3.  Check for physical damage. Look for internal and external physical damage. Any damage will prevent the appliance or air conditioner from functioning properly. Two examples are broken parts at the base of the washing machine or a damaged cabinet that prevents the doors from closing properly.

4.  Check the controls. The controls must be set to the proper settings. If the controls are not set correctly, the appliance or air conditioner might not function properly or complete its cycle.

5.  Operate the product. Operate the appliance or air conditioner, and let it run through its cycle. Check the cycle operation against the operational sequence of events that is listed in the use and care manual.

6.  Is the product operating properly? If it is, explain to the consumer how to operate the appliance or air conditioner according to the manufacturer’s specifications.

7.  The product is not operating properly. If the appliance or air conditioner is not operating properly, proceed to locate which component has failed. Check the diagnostic charts that are listed in this book to assist you in the correct direction to take.

Diagnosis and Correction Procedure

When diagnosing a problem with an appliance or air conditioner, use your five senses to determine the condition of the product. This will help in analyzing and defining the problem:

•  Example #1: When turning on the washing machine, there is a smell of something burning. You can track down the location of the burning smell and therefore discover which part has failed.

•  Example #2: When turning on a dishwasher, unusual noises are heard coming from underneath the machine. Stop the dishwasher and attempt to track down where the noises are coming from.

Along with your hand tools, there are a variety of test meters that can assist you in analyzing and defining the problem. This is the sequence of events to follow when servicing an appliance or air conditioner:

•  Unplug the product   Change the range setting on the multimeter to voltage. Check the voltage from the appliance or air conditioner’s receptacle. If there is an uncertainty, check the name plate rating for the correct voltage rating; this is located on the product. When diagnosing a component failure, there are three types of circuit failure—the open circuit, the grounded circuit, and the short circuit—all of which are thoroughly explained in Chapter 6.

•  Gain access   Only remove the panels and screws necessary to gain access to where the suspected component failure is located.

•  Isolate and/or remove the defective part   Using the multimeter, isolate and/or remove the part, set the range to ohms, and check for component failure. This will be further explained in Chapter 6 and then in Chapters 14 through 30.

•  Install the new component   When you find a defective part, replace it with a new original part. Reconnect all the wires in their original places.

•  Reattach all panels and screws   Close the appliance or air conditioner, and reattach all panels and screws.

•  Test the product for proper operation   Plug in the appliance or air conditioner and test it.

Technicians Diagnostic Guide

Before a technician begins to service an appliance or air conditioner, he or she must check the following conditions before the service call begins, during the diagnostic phase of the service call, and after the service call is completed:

•  Make sure that there is the correct voltage at the receptacle for the appliance or air conditioner to operate correctly.

•  Check and see if a fuse has blown or a circuit breaker has tripped.

•  Check and see if the appliance or air conditioner has been installed according to the manufacturer’s instructions.

•  All meter readings should be made with a multimeter (VOM or DVM) with a sensitivity of 20,000 ohms per volt DC or greater.

•  Locate the technical data sheet in the product. It is usually located behind the control panel or tucked away on the bottom of the product behind an access panel. The technical data sheet contains the wiring diagram and other useful information needed to complete the repairs.

•  On electronic models you will need the actual service manual for the model you are working on to properly diagnose the product. The service manual will assist you in properly placing the product in the service test mode for testing the product functions.

•  During the diagnostic part of the service call, check all connections first before you replace any parts. Check for loose connections or burnt wires. During the testing phase you will have to disconnect and reconnect wires. Be careful not to pull on the wires; you might pull the wire off the terminal connector.

•  Check all wire harness connectors first. Inspect each wire harness connector and make sure that there are no loose or broken wires on the connectors. Make sure that all wires are pressed into the connector properly.

•  Resistance checks must be performed with the service cord removed from the receptacle.

•  Voltage checks must be performed with the service cord plugged into the receptacle with the correct voltage present.

•  When you complete the service call, make sure that the appliance or air conditioner operates according to the manufacturer’s specifications.