Air Conditioner Maintenance Tips

Proper operation of an air conditioner depends on efficient air circulation. To maintain this circulation, it's important to keep the filters and the coils clean. It's also important to prevent leaks by checking for clogs in the drainage system and clearing them. You can and should conduct a few other maintenance procedures, but you need a licensed technician to handle maintenance of the refrigeration system or the condenser. This isn't a matter of skill level—the law requires it. With proper maintenance, a typical air conditioner should easily last from 12 to 15 years.

handsome young man electrician installing air conditioning in client house
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You need a licensed technician to handle maintenance of the refrigeration system or the condenser.

Understanding Air Conditioners

An air conditioner has two sets of coils. One set contains liquid refrigerant that has been compressed by the condenser—the electric pump whose humming tells you the air conditioner is running. The other set contains the same refrigerant, but in its vapor form. The evaporation that takes place in these coils is what produces the cooling. One fan in the air conditioner blows the cool air from the evaporative coils through the front grille into the house, while another fan exhausts warm air from the condenser coils to the outside. The entire process depends on efficient air circulation.

Keep the Filters Clean

The main filter on a window air conditioner is usually located right behind the grille, which typically unsnaps to give you access. You should clean or replace this filter at least once a year or more often if the air is dusty or you notice the air conditioner isn't cooling as well as it should. A dirty filter can reduce an air conditioner's efficiency by 5 to 15 percent. The filters in a central air conditioner are located somewhere in the air return duct, typically in a wall ceiling or in the condenser unit itself. These also need cleaning or replacement at least once a year.

Clean the Coils

If the filters are clean, it's unlikely that dust will accumulate on the evaporative or condenser coils, but you should still check them when you clean the filters. You can usually see the coils on a window unit when you remove the filter, and a good way to clean them is to blow air using a hairdryer. In some cases, you may need to brush off the dust with a lightweight brush. Be sure to unplug the unit first. The procedure is basically the same for cleaning the coils on a central air conditioning condenser.

Check the Drainage

Condensation from the air naturally collects on the evaporative coils, and an internal drainage system collects this water and routes it to a drainage pan or, in the case of a central air conditioning unit, to the building's waste system. Check the drain channels yearly by passing a length of 16- or 18-gauge wire through them to clear any blockages. If you have a window air conditioner, be sure to also check the drainage hole in the drain pan and clear obstructions. Otherwise, the water can back up and leak onto the floor.

Inspect Window Air Conditioner Seals

Condensation may collect on a window unit that isn't properly sealed to the window frame. This happens because warm air passing through the gap between the air conditioner and the frame promotes condensation from the cooler air inside. Check the gap for drafts yearly and seal them out using weatherstripping. If water continues to drip after clearing the drains and sealing gaps, you may need to re-level the unit. It should have a slight backward slope to allow water to drain to the outside of the building rather than inward.

Straighten the Fins

The grille on the outside of a window or central cooling unit consists of an array of aluminum fins that keep debris out of the unit while allowing the air to pass. These are made from thin aluminum and bend easily. You should check them once a year and straighten any bent fins using a tool known as a fin comb. You can also use this tool to clean debris that has collected between the fins.

Get a Professional Inspection

Problems that arise with the refrigeration system itself, including refrigerant leaks and condenser malfunctions, can greatly affect cooling performance. To avoid the release of potentially damaging refrigerants into the atmosphere, the Environmental Protection Agency (EPA) requires licensed technicians to follow specific procedures when servicing refrigeration systems. To keep your air conditioners in top form, get them inspected periodically by a licensed pro.

Chris Deziel

Chris Deziel

Chris Deziel is a contractor, builder and general fix-it pro who has been active in the construction trades for 40 years. He has degrees in science and humanities and years of teaching experience, and he is also an avid craftsman and musician. He began writing on home improvement topics in 2010 and worked as an expert consultant with eHow Now and Pro Referral -- a Home Depot site. He currently contributes a monthly property maintenance blog on A DIYer by nature, Deziel regularly shares tips and tricks for a better home and garden at