Window Air Conditioner Problems
Borrowed from RepairClinic.com

You hear the motor running, but there is no air blowing out
Your air conditioner is equipped with a compressor and a fan motor. The compressor may be running but the fan motor may not be. Unplug the unit and remove the cover. Locate and try to move the fan blade. If it is very difficult to rotate, the fan motor needs to be replaced. If the blade turns easily, the circuit powering the fan motor will is probably the problem and you will need a qualified service technician to determine the cause. It could be a problem with the capacitor, the selector switch or the motor itself.

The unit doesn't turn on
Check to see if there is power getting to the air conditioner by plugging a lamp or other device into the same outlet the air conditioner is plugged into. Check the fuses or circuit breakers if there's no power. If the problem is not with a fuse or circuit breaker, it's time to contact a qualified electrician to repair the outlet.

If the outlet is working but the air conditioner is not, the problem may be with one of the following:

• Broken or burnt wiring
• Thermostat
• Compressor
• Overload and/or relay
• Selector switch
• Control board

Work on these areas of an appliance will probably require help from a qualified repair technician.

The fan runs but the air isn't cold
Check the following:

1) Make sure the thermostat knob is turned to the proper setting.

2) Check to see if the compressor motor is running. (The compressor is a football-sized case with no apparent moving parts located inside the air conditioner at the center. If it is making a continuous noise, and your air conditioner is still not cooling, there may be a serious problem with one or more of these areas:

• Compressor
• Condenser
• Overload and/or relay
• Evaporator
• Thermostat (Open thermostat)
• Burnt wiring
• Bad selector switch
• Capacitor
  
  These items are not user serviceable. You will need to contact a qualified appliance repair technician to repair these components.

The air doesn't seem cold enough
If the air doesn't seem very cold, you can use a thermometer to check the difference in temperature between the air going into the unit and the air being blown into the room. If the unit is working properly, the difference in temperatures should be at least 15 degrees. If the temperature difference is less than 15 degrees you should check the following:

1) Air damper - Check to make sure the air damper is closed. If it's open, it will bring in outside air and reduce the efficiency of the unit.

2) Back cover - Many people cover their air conditioners during the winter to protect the unit from the weather and sometimes forget to remove the cover. Make sure the outside cover has been removed.

3) Condensing coils - The condensing coils are located on the side that faces outside of the room to be cooled, usually the outside. Make sure the coils are clean and free of lint, dirt and dust. Air is blown directly out through the condenser coils. If the coils are clogged, the cooling system cannot provide the cooling necessary. Pull the unit out of the wall or remove the cover to access to the coils. Blow compressed air at the coils or use a soft bristle brush to remove the dirt. Also clean any dirt build-up from the bottom of the air conditioner so the water will evaporate correctly.

The unit runs constantly
(This is normal on some models with fans that are set to run continually.)

If the unit is supposed to turn off and it doesn't, you will need to check the following:

1) Make sure the unit is cooling correctly. See the section entitled "The air doesn't seem cold enough."

2) Check the room temperature. If the temperature is fine, try adjusting the thermostat to a slightly higher setting. If the unit works fine, then leave the thermostat set to the higher setting.

3) If the room is not cool enough, but the unit is running properly, the air conditioner may be undersized for the room. You can try to compensate for the size problem by closing doors or making the space smaller with partitions.

The following chart will help match the right sized unit to your room:

AREA TO BE COOLED	CAPACITY
100 to 150 square feet	5,000 BTU
150 to 250 square feet	6,000 BTU
250 to 300 square feet	7,000 BTU
300 to 350 square feet	8,000 BTU
350 to 400 square feet	9,000 BTU
400 to 450 square feet	10,000 BTU
450 to 550 square feet	12,000 BTU
550 to 700 square feet	14,000 BTU
700 to 1000 square feet	18,000 BTU

Note: You can reduce needed capacity by 10% if the room is heavily shaded, but you will need to increase the capacity by 10% if the room receives a lot of direct sunlight. If the room is used consistently by more than two people, for each additional person using the room you should add 600 BTU. For units used in kitchens, you should add 4,000 to 6,000 BTU.

You can hear water splashing inside the unit
Window air conditioners remove moisture from the air. The moisture is collected in the bottom pan of the air conditioner where it should evaporate. The water drips down off the evaporator coils and collects in the pan at the bottom of the air conditioner. The air conditioner will be tilted slightly back if it is installed properly forcing the water to collect near the back of the unit. When the fan blades spin to cool the rear condensing coils they will come close to touching the inside of the pan where the water has settled. If the water is deep enough for the fan ring to touch it, the ring will pick up some of the water and blow it at the condensing coils. The warm coils evaporate the moisture to the outside. This is the splashing sound you hear. If no water is leaking inside the room, there is no cause for alarm.

If there is water leaking, make sure the unit is tilted back - never drill holes into the bottom of unit to let the water escape.

The unit rattles loudly when it turns off
Air conditioner compressors are powerful motors. The compressor starting up and shutting off will often cause the whole air conditioner unit to shake or vibrate loudly. This is normal and usually can not be eliminated.

First make sure the air conditioner is properly mounted and secured in the window frame. If not properly installed, when the unit shakes it could shake free of the frame.

Also check the compressor mounting pads and/or brackets, they could be worn out or missing making the noise more noticeable. Often the pads and brackets can be replaced, reducing the problem.

There is water leaking out of the front of the unit
When an air conditioner runs, water collects in the pan at the base of the unit. If the unit is not installed so that it is tilting slightly backwards, the water can leak out the front. Reinstalling the unit correctly should solve the problem.

The unit is blowing musty smelling air
Air conditioners remove moisture from the air which collects in the pan at the base of the unit. Normally the water completely evaporates out of the unit but sometimes some water will sit in the base of the air conditioner for long periods of time and become stagnant. Although there is no easy way to prevent this problem, you can reduce it by carefully cleaning the evaporator pan at least once a year. Removing any dirt, lint or dust from the pan should prevent mold and mildew from growing. Replacing the filter behind or in the front cover can also aleviate the problem.