Easy Steps to Keep Your Air-Conditioning Unit Running Smoothly

Regular cleaning and maintenance will save you money and extend the life of your heat pump or HVAC unit.

HVAC System

Photo by: fstop123; Getty Images

fstop123; Getty Images

Maintain your air-conditioner, and you’ll not only save money on energy, but you’ll also extend its lifespan, saving money on costly early replacement. "Maintaining your AC unit is important for energy efficiency, comfort, for overall occupant health and overall unit function," says Dr. Sarah D. Kirby, state program leader for Family & Consumer Sciences and a professor at North Carolina State University.

Dr, Kirby, who is also the assistant director of the NC State Extension, says a properly running air conditioner removes excess moisture in the air, keeping occupants comfortable. Dirty air conditioners or improperly operating systems can lead to the growth of microrganisms such as mold, which can exacerbate allergies and asthma, she says.

The best time to use these tips is just before each cooling season begins. Your Heating, Ventilating, and Air-Conditioning system (HVAC) will consist of either a furnace and AC or a heat pump, which both heats and cools. Both types will have an interior unit (evaporator and blower) and an exterior unit (condenser coil and compressor). These instructions apply to a whole-home air-conditioning or heat pump unit.

1. Shut Off the Power

Due to the dangers of working around electricity and the air-conditioner’s moving parts, it’s essential to completely turn off power to the unit. On the exterior condenser/compressor, look for an exterior shut-off box near the unit (Image 1). Also, turn the power off at the breaker box located inside (Image 2).

2. Remove Debris

On the exterior condenser/compressor, remove the fan cage. Using a screwdriver or wrench, remove the fasteners, and lift the cage or fan grill away from the top of the unit. By hand, or with a wet/dry vacuum, clean leaves and other debris from the interior.

Remove the fan cage to gain access to the interior of the condensor unit.

Remove the fan cage to gain access to the interior of the condensor unit.

Photo by: Sherri James

Sherri James

3. Clean the Fins

Remove the outer covers and use the brush attachment on a powerful shop vacuum to remove all outside dirt. Then, using a gentle stream from a garden hose, spray through the fins from the inside out to remove any built-up dirt or debris from between them (Image 1). Never use a pressure washer, since the pressure can damage the fins.

If the fins are particularly dirty, use a commercially available fin cleaning spray available at home improvement centers (Image 2). Read and follow manufacturer directions.

4. Straighten the Fins + Clean the Area

Since any reduction in air-flow through the fins can reduce efficiency, carefully straighten bent fins using a butter knife or commercially available fin-straightening tool. Be gentle so that the tubing embedded within the fins is not damaged.

A butter knife will work as a fin-straightening tool.

A butter knife will work as a fin-straightening tool.

Photo by: Sherri James

Sherri James

5. Clean Area Around the Unit

Once finished with the cleaning, replace the fan cage. Rake back leaves and debris outside the condenser, and cut back branches and vegetation at least two feet in all directions to ensure proper airflow around the unit. During winter months when the condenser is not in use, it’s good to cover the top of the unit with a piece of plywood or plastic to keep debris from falling in. However, don’t completely cover the unit’s sides, since moisture can build up inside and cause corrosion. Also, a completely covered unit encourages vermin to build nests inside. Remove any cover when the unit is operating.

6. Level the Unit

Over time, the pad where the condenser unit sits can begin to tip as the soil settles beneath it. An out-of-level condenser unit can cause the compressor within to fail early. Check to see that the condenser is level, and use rot-resistant shims to bring it back to level. Service Experts’ Moody adds, "If you have a heat pump system, it’s okay for the pad to be slightly sloped away from the home’s foundation to allow for defrost run-off during the winter."

The condenser unit must be level to operate correctly, or, in the case of a heat pump, sloped slightly away from the home’s foundation.

The condenser unit must be level to operate correctly, or, in the case of a heat pump, sloped slightly away from the home’s foundation.

Photo by: Sherri James

Sherri James

7. Clean the Evaporator Coil

Now it’s time to move inside. On the inside blower/furnace unit, find the evaporator coil door. You may need to remove some foil duct tape and take out a few screws or bolts. Inside, use a soft brush to dust off the coil, then spray the coil with commercially-available, no-rinse coil cleaner (available at home improvement stores). The spray will foam up and then drip into the drain pan. Clean out the drain pan with soap, hot water and a little bleach. Then, pour a cup of 50 percent bleach/50 percent water down the drain. To keep the drain clear longer-term, place a commercially available drain pan tablet in the pan. This will inhibit future algae growth.

If the bleach solution drains easily, skip the next step. If not, move on to Clean the Evaporator Drain. Replace the evaporator coil door, and use foil duct tape to reseal, if necessary.

Spray the evaporator coil with a commercially available coil cleaning spray.

Spray the evaporator coil with a commercially available coil cleaning spray.

8. Clean the Evaporator Drain

Warm, humid air from your home’s interior is blown through the evaporator coil on the interior. The cold coil absorbs heat from the air, cooling it, before the air is circulated back into your home. The humidity in the air condenses on the cool surface of the evaporator coil as liquid water, dripping into a pan below. From the pan, the water flows into a drain tube which is typically routed into a basement floor drain, utility sink or outside.

Over time, algae and mold can build up and potentially plug the drain, so if the drain is either not flowing or flowing very slowly, it will need to be unplugged. A plugged drain can either cause damage by flooding onto the floor or, if the system is equipped with a drain float, cause the system to stop cooling in order to avoid flooding.

First, find the drain line where it leaves the evaporator coil enclosure. The drain is usually a 1-inch PVC pipe (white, gray or black). Follow it to the end where it drains. Often the line drains outside near the condenser unit, but it can also drain into a utility sink or basement floor drain or, in the case of attic units, down an outside wall.

Once located, use a wet/dry vacuum to clear the drain. It’s best to remove the paper filter from the wet/dry vacuum so as not to ruin the filter. Hold the hose of the wet/dry vacuum to the end of the drain line. You can use duct tape or simply hold a rag around the gap. Turn on the vacuum for 2-3 minutes then turn off. This will clear the drain of any growing biological matter.

Hold a rag around the gap between the vacuum hose and the drain.

Hold a rag around the gap between the vacuum hose and the drain.

Photo by: Sherri James

Sherri James

9. Change the Blower Filter

The filter in your HVAC system should be changed at least twice a year — once just before the heating season begins and once before the cooling season begins. If you live in a particularly dusty area, you may want to change it more often. Always replace the filter with a new filter that has the same airflow rating. "Be careful with 'air purifying' or HEPA filters," Moody cautions, "because they can dramatically reduce airflow in your system. That can cause the indoor coil to freeze because of the reduced airflow."

Locate the filter enclosure on the indoor furnace/AC where the large fresh air return duct enters the unit. You may need a screwdriver to turn the latch to open the door to the filter enclosure. Remove the old filter and install the new filter, matching the air-flow direction arrows on the filter to the arrows on the unit. Close and latch the door.

Most filters need to be replaced at least twice a year.

Most filters need to be replaced at least twice a year.

Photo by: Sherri James

Sherri James

10. Turn the Power Back On

While these steps will help to keep your AC system in top shape, be aware that there are maintenance items that only a trained HVAC technician will be able to do. For example, a slow refrigerant leak in your AC system can lead to expensive compressor failure, but a homeowner doesn’t have the tools or skills necessary to check refrigerant levels. Also, clean ducts and proper airflow are essential to a well-functioning system, but homeowners lack the necessary equipment for the job. The bottom line? While some AC maintenance can be done by a savvy homeowner, it’s still necessary to have an expert technician check the system periodically. Dr. Kirby suggests a service in the spring before the cooling season and then again in the fall before the heating season.

"Just like anything else, when you keep it (air conditioning unit) in good running condition, it will last longer and issues can be addressed before they become major, or worse yet, an emergency," she says.

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