The Basics

If you think about it, you probably spend some time cleaning your oven (or at least setting it to clean itself) and vacuuming the coils on your refrigerator (if you don’t, you should as it can prevent premature failure of that appliance!). It makes sense, then, that you spend a little time each month making sure your HVAC system is clean, tight and bright, as my high school auto shop teacher used to say about cars. He was a wise man and if heeded, his words could save you a lot of money and trouble in the long run.

The most common type of HVAC system in use is the split system. It is composed of an inside unit that contains a furnace, an evaporator and an air-handling unit, and an outside unit that houses a condenser and compressor. Both units share a need to be clean to operate at their peak efficiency.

The inside portion of a standard HVAC system is shown above. Notice the clutter around the unit on the left. It’s best to keep the area around the unit as clean and clutter-free as possible. This unit is in a basement. HVAC systems can also be located in an attic or crawl space.

KEEP IT CLUTTER-FREE

Both the inside and outside units of a split system need their breathing room. Inside, a gas furnace needs good airflow for proper operation. It’s also a good idea to keep anything combustible away from the unit.

With the space around this equipment clear of obstructions, it has better airflow and can operate more efficiently when the furnace is running.

The outside compressor needs airflow as well to run at top efficiency. Keep the area around the unit clear of unnecessary clutter and debris. Do not store gas cans or other combustible materials near it.

We’ll cover more on how to make sure this unit is working properly later, but simply keeping the area clean around it is a good start!

The picture at right shows a compressor with too much clutter around it. It’s especially unwise to store things like gasoline around this unit!

Sweep away any dirt and debris from around the compressor unit.

The area is clean and clear of obstructions, as it should be.

Checking & Replacing Filters

Inside your home, the single most important thing you can do to ensure the long life and health of your furnace and air handler is change the filters on a monthly basis. It sounds so simple, and yet it is the one thing that comes up again and again when I talk to friends in the HVAC business. If people would simply change their filters monthly and have their systems serviced once a year, the world would be a happier place. OK, well maybe just inside your home — but that’s a start!

The process is simple. The air intakes (the number you have depends on the size and number of systems your home has) pull air from inside your home and send it through the air handler once it’s been heated or cooled. Because so much air is passed through these intakes over the course of each day, the crud that builds on their surface is pretty incredible — and sometimes disgusting.

Above left is a look at an air filter that was in place for about two months in a 3500 square foot home. It’s one of three filters in the home. The clear area in the middle is where a small piece of the plastic cello packaging got stuck when it was installed. It shows you how much crud, dirt, dander and dust are caught before they can enter the mechanics of your system! At right is another of the filters on the same system.

The photo at left shows a new filter on the left sitting next to a two-month-old filter on the right. Notice that there is NO light coming through the dirty filter. This homeowner waited too long to change the filter and probably paid for it in higher utility bills!

Think of the system like your car. When your car’s air filter gets clogged with debris like this, your car starts to run poorly, getting bad gas mileage. You notice it when you go to fill up and see that you’re not getting the miles per gallon that you’re used to.

In your home, you may notice that rooms are getting too hot or too cold or that there is a minimal amount of air coming out of the vents. These are signs that the system is having a hard time breathing! Time to change the filter!

First, turn the system to the “Off” position.

Locate the return air grills on your system. Remember, there could be more than 1, and all filters should be changed at the same time.

Most modern system thermostats have an “Off” position. If yours does not, simply turn the thermostat to a setting that will prevent the unit from coming on during the procedure. In other words, turn the system to “Heat” and lower the temperature to the lowest setting.

Both of these return ducts are located in the same home and the filters should be changed at the same time to ensure system efficiency!

The intake grates will have either small levers or screws that allow them to hinge down, exposing the filter. Sometimes these tiny levers get a little tough to open. You can use a screwdriver or even a coin to pry them up if you can’t get them released with your fingers.

Once you open the grill, carefully pry out the old, dirty filter, being careful not to shake off too much of the debris stuck to it.

Install the new filter, making sure the airflow arrows are pointing inward.

It’s a good idea to mark the filter with the date you changed it. That way, there’s no doubt when it should be changed again!

Notice that the filter above became so clogged that the system almost pulled it into the duct! This type of distortion of the filter means that the owner waited too long to change it out for a new one!

Finally, before closing the grill, use a vacuum to clean up around the entire intake area. This will keep the dust, dirt and hair that’s accumulated from ending up in the filter in the next 10 minutes!

Just like the equipment itself, the return air grates must be kept free of clutter and debris — or, furniture, as it were. Putting tables or chairs in front of them can inhibit airflow and cause your system to waste energy.

Fixing Hot & Cold Spots

Every house has them — or at least every house I’ve ever been in, anyway. They are hot and cold spots and they’re annoying at best.

You may have a bedroom that stays too hot in the summer and too cold in the winter. Or maybe some other room in your home just seems uncooperative when it comes to air conditioning. The good news is the problem is most likely a simple fix.

Let’s start with the most obvious — the supply-air grill. If it has adjustable louvers, they may simply be closed too much. If a room is uncomfortable during any time of the year when the system’s running, this could be the problem.

Simply opening the louvers on a vent grill can make a room more comfortable, especially if the louvers have been in the closed position. Closing off vents also puts stress on the rest of the system and can damage the air-handling unit. A vent should never be completely closed for that reason.

If adjusting the vent louvers doesn’t fix the issue, try tracing the duct back to the main air-handling unit. It may run in the attic or the basement. Once you find it, there’s a good chance that it has an air damper lever somewhere along its run.

The air damper acts like a stopper inside the duct itself — allowing more or less air to flow through the duct and to the vents in each room. It’s possible that the damper is restricting airflow to such a degree that it’s causing some rooms to be uncomfortable.

The lever on the duct is oriented in-line with the damper disc inside. In this photo, you can see that the damper is nearly closed.

By moving the lever slightly, airflow through the duct is increased and may cure the imbalanced system. Care should be taken to move the lever in small incremental amounts. For instance, if you think about it in terms of a clock, the lever above is slightly past the two o’clock position. By moving it only to the four o’clock position, the problem may be cured. To change the damper’s position, loosen the wing nut, turn the lever slightly, then tighten the nut to prevent the damper from moving around.

Another view of a duct damper lever. If the lever is hard to move, try loosening the wing nut on the pivot post. Be sure to retighten after adjustment.

Adjusting the dampers on your system can be tricky. It can cause reduced air pressure to the rest of your home and may cause heating and cooling issues in other rooms. For this reason, be sure you make only minor adjustments! If there is no result or if it causes problems in other areas of your home, the damper may not be the issue!

While not as likely, another area to check is the connection of the ducts to the main trunk of the line. I’ve seen ducting that’s come completely loose from the main due to recent maintenance in a home. It might have just slipped slightly due to air pressure or being bumped or jarred.

Obviously this duct won’t be doing the inside of the house any favors! Care should be taken when fitting the two ends together, as the edges of metal ducting can be very sharp!

Locating a Leak

Far more likely than the obvious disconnected duct is a loose connection or damaged duct. Over the years, especially in older homes, the tape used to connect metal duct can fail. It may be a metal tape or a white or gray material used to secure the joint.

The simplest cure for this type of leak is to wrap the joint with a modern duct-sealing tape. Use at least two or three wraps and check for any air leaking from the duct after the repair.

When dealing with flexible duct, the same rule applies. If you find a leaky joint or a tear in the jacket around the duct, use repair tape to seal up the leak. In the case of small tears, it’s not necessary to wrap the tape completely around the duct; just be sure to seal the hole with an adequately sized patch.

If, after checking the entire system and making the adjustments and/or repairs above, your system still isn’t performing as you think it should, there’s still hope! It may need a good cleaning and refrigerant charge. While I recommend you leave the charging to the pros, you can certainly do some of the cleaning yourself.

SAFETY FIRST!

In some older homes, a sealing tape containing asbestos was used to seal joints in HVAC systems. Use caution if you suspect this to be the case in your home. While the tape poses little danger according to many reports, you may wish to have a professional inspect your system and advise you of the best course of action.

This joint started leaking because the tape originally used to seal it had failed. Several wraps of a modern sealing tape was all it took to stop the energy-wasting leak!

Flexible duct can be damaged in a number of ways. Even if the damage does not penetrate through to the air-carrying core, it’s a good idea to seal up areas like this to prevent further damage from occurring.

Use enough tape to adequately cover the damaged area and use moderate pressure to make sure it sticks. If the area to be patched is dusty or dirty, clean it with a damp sponge or rag before applying the patch.

POWERED VENT

If all else fails, you can try using a powered vent. It works with a built-in thermostat to pull more air into the room you’re trying to adjust. It simply replaces the existing grill and plugs into the wall. These are available for around $60.

SYSTEM CHECK TOOL

Thermal leak detectors like this one can be used to find energy leaks around your home. They’re also good for checking the temperature of the air coming from your HVAC system. They can alert you to a potential problem!

Cleaning the Condenser Unit

Generally, this service is included in an annual inspection/tune-up package from a pro, but I like to give my outside unit a good cleaning before shutting it down for the winter.

Some HVAC systems have only one outside condenser unit, while some homes have multiple systems servicing different areas of the house. It’s important to know which system you’re dealing with before making adjustments or repairs and cleaning. If you’re not sure, a local HVAC service pro can help you in identifying each unit.

A close inspection of the metal fins around the condenser unit can tell you whether it needs to be cleaned. Remember, it needs good airflow to work properly and if the fins are clogged or bent, the restricted airflow could cause your system to work with less than stellar results!

The first thing to do is make sure the system thermostat is turned to the “Off” position.

The main power going to the unit must also be turned off. In most cases, there is a breaker near the unit. You may have to pull the fuses out or turn the switch “Off”.

Condensing units shapes and sizes. You can also look up information online about your specific model.

When working around breakers (especially 220 volt breakers), it’s a good idea to tape off the breaker while you’re working with the unit. While you may be the only one at home, the tape serves as a good reminder for yourself, as well.

While it may not look like much, this dirt and debris can cause significant airflow restriction and make your cooling system waste energy. Again, in terms of your car, when its radiator becomes clogged like this, it causes your car to overheat and has the potential to damage your engine!

Once the power is off, it’s a good idea to blow any loose debris from around the unit. If you have an air compressor or a blower, either will do the trick. Be careful not to aim the airstream directly at the fins, as it can cause damage by bending the fins. A gentle stream of water from a garden hose will also work.

Once all the loose crud is removed, it’s time to take a look inside. The top of the compressor is usually held in place with several screws. Be sure to familiarize yourself with the locations of the screws that hold the top on and don’t remove any other fasteners.

You should also note that the fan is connected directly to the top of the unit and can make it very heavy. You may need help removing it.

If the wiring between the unit and top is short, find a way to secure the top so that you can access the inside of the unit. You may have to lean it against a nearby wall or have someone hold it while you clean. Again, use extreme caution and care during this process to avoid damaging the equipment or hurting yourself!

Use a vacuum to remove leaves and other debris from inside the unit.

In the photo above, the top has been removed and set to the side. Be careful that it doesn’t lean against the fins of the unit! Also, be careful not to bend or damage the fan blades, as this could cause them to become unbalanced.

Once cleared of debris, use a garden hose (set to shower or flat) to wet down the fins on the coil. Just like air pressure can damage the fins, so can excess water pressure, so be sure to be gentle but firm on this step.

The idea behind this step is to loosen up the crud and grime so the cleaner can do its job. I like to spray from the inside out to avoid pressing debris farther into the coil fins.

There are several brands of cleaners available to clean the the coils. You can usually find them in the HVAC area of the hardware or home improvement store for under $10 a can.

Be sure to follow all label instructions and use all necessary safety gear, including goggles to avoid getting any product into your eyes!

According to the manufacturer’s instructions, spray the cleaner onto the outside of the coil fins and allow it to cut through the grime.

Once the cleaner has had a chance to work, use the hose, again spraying from the inside out, until the water runs clear through the coil.

When the debris is cleared from the fins, the water should run through the coil to the outside, forcing any remaining material with it.

Once clean, you should be able to see light through the unit. This will ensure optimum airflow.

Replace the top, reinstall the fasteners and turn the breaker to the unit back to the “On” position. Then restart the thermostat and see if your system does a better job cooling your home.

Fin Damage

As noted earlier, it’s important to avoid bending the fins on the system. This blocks air from flowing across the coil and causes heat buildup. If you accidentally damage the fins or if your unit has been dented in the past, there are a couple of ways to fix the problem, using extreme care!

First, a small screwdriver can be used to gently straighten the fins, but can be very time consuming and tedious.

There are also specialty tools called “fin combs” designed to do the job. They are readily available online or in some auto-parts stores.

Before you purchase one, measure the number of fins per linear inch on your compressor and buy a comb that has that number of fins. Take your time during the straightening process to avoid further damage!

Also be aware that it takes some finesse to use a tool like this. Don’t get frustrated if you don’t get perfect results right away!

A fin comb can straighten most dents in the condenser unit. Use caution and take your time during the process. These combs run anywhere from less than $10 to more than $20.

Winterizing the Condenser Unit

Once you know you won’t be using your air conditioner for the season, it’s a good idea to cover it up. You can sometimes find custom covers at hardware stores, but the simplest way to do it is with a tarp.

Wrap the unit so that the folds of the tarp won’t collect rainwater and secure it with bungee cords or clips. Be sure to uncover it before the first use the following season! A good way to prevent accidental damage is by removing the breaker or disconnect from the panel next to the unit and placing it under the tarp.

A cover will prevent a season’s worth of leaves and debris from collecting inside the unit while it sits unused.