How to Repair Window & Room Air Conditioners How to Repair Window & Room Air Conditioners
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How to Repair Window & Room Air Conditioners

©Don Vandervort, HomeTips

Parts of a Window Air Conditioner

If your room or window air conditioner doesn’t cool or turn on, this expert guide to AC repairs will help.

Most problems with window and room air conditioners can be categorized under a few symptoms: they do not cool sufficiently, they do not turn on at all, or they make noise. Here is a closer look at how to troubleshoot and repair these issues. If your window or room air conditioner is beyond repair, be sure to see Buying the Best Window Air Conditioner or Room AC Unit.

Air Conditioner Doesn’t Cool

A window or room air conditioner that doesn’t cool may need to be recharged with refrigerant, but the chances are good it simply needs to be cleaned. You can do this yourself, which involves disassembling the unit, or you can call an air-conditioning or appliance repair professional. Before attempting the work yourself, consult your owner’s manual and make sure you have the right skills and tools to handle the task. If you can’t find your appliance’s manual, search for one online, using your air conditioner’s make and model number.

Following is what a typical manual advises:

1Unplug the unit and carefully remove it from the window or wall. Put the air conditioner somewhere outdoors or in the garage where you can work on it.

2Remove the grille and filter and unscrew the metal case (taking care not to damage the coil’s fins).


3Wash the filter thoroughly or replace it with a new filter; most air conditioner filters are readily available online or at appliance repair shops.

4Using a vacuum with a soft brush attachment, clean the coil’s fins.

5Spray water back through the fins from the fan side (protect the wiring and the motor with plastic).

6Clean the unit up with a rag, making sure all drains that allow condensed water to drip away from the unit are open. Allow it to dry thoroughly.

7Lubrication. While you have the unit apart, lubricate the motor and bearings according to your owner’s manual.

8Finally, reassemble and reinstall the unit.

Air Conditioner Doesn’t Turn On

Window and room air conditioners draw a lot of electrical power, which can lead to less than peak performance or even complete failure. If your room air conditioner doesn’t turn on:

©Don Vandervort, HomeTips

Turn the circuit breaker all of the way off, then flip it back to “ON.”

1Be sure the unit is plugged in and that its switch is turned on.

2Make sure the outlet works using a voltage tester or by plugging in a light that works (only for standard-voltage models—do not plug a light into a 220/240- volt receptacle). For more about testing an outlet, see Electrical Wiring Problems.

3If the light doesn’t go on, the circuit has probably overloaded—check the electric panel or fuse box and reset the breaker or replace the fuse.

4If the light works, it’s likely that the air conditioner’s switch is faulty or the thermostat needs adjustment or repair. See more about these repairs in the video below.

5Be sure the thermostat is set to “cool” and below room temperature.


6Refer to the owner’s manual for thermostat repair. If repairing the thermostat doesn’t solve the problem, unplug the unit and call an air conditioner repair person.

Air Conditioner Makes Noise

If an air conditioner is making too much noise—the problem may be that it has bad bearings, something that is best handled by an an appliance repair person. On the other hand, you may be able to solve the issue with basic lubrication. Please see the video below for more about how to oil or replace the bearings.

Air Conditioner Troubleshooting Video

The very comprehensive video below does a great job of showing you how to troubleshoot a window air conditioner for various problems. It begins with a discussion of how an air conditioner works, and then moves on to various troubleshooting methods and maintenance.

We especially like the way he shows how to test whether or not the unit’s thermostat is working, using a multimeter’s continuity tester and an ice cube.

Note, though this video discusses fixing a refrigerant leak and dealing with the unit’s compressor, both of which are beyond the scope of do-it-yourself repairs. Again, please take the unit to an appliance repair person.

Call for free estimates from local pros now:

About Don Vandervort
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Don Vandervort developed his expertise more than 30 years ago as Building Editor for both Sunset Books and Home Magazine. He has written more than 30 home improvement books and countless magazine articles. He appeared regularly on HGTV’s “The Fix,” and served as MSN’s home expert. Don founded HomeTips in 1996.

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