PreparationIs There a Way to Reset the Compressor on a Window Mounted AC?
Yes, there is a way to reset the compressor on a window mounted air conditioner. Your window mounted air conditioner has a reset button mounted near the power cord that makes the entire air conditioner go back to factory defaults, including the air compressor. It also helps to unplug the air conditioner to clear the air conditioner’s settings.

Turn the window mounted air conditioner off and unplug the cord from the wall. Let the window mounted air conditioner sit for ten minutes for all the power to go out from the capacitors in the unit.

Powering
Plug the power cord back into the wall outlet and turn the window mounted air conditioner back on. Turn the cooling dial down to the point where the compressor engages. If the compressor engages, then the unplugging was sufficient to reset the air compressor if not, advance to the next section.

Resetting
Press the reset button located near the power cord for five seconds and then take your finger off the button. Wait ten minutes for the air conditioner to work through the reset operation. Turn the air conditioner cooling dial down for the air compressor to engage. If it does not, then the compressor may be faulty.

Servicing
If the previous steps were not sufficient to fix the window mounted air conditioner, then the compressor needs to be serviced as resetting will not fix the problem.

Fan and Fan Motor

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If your window air conditioner is not blowing cold air, the problem could be the fan or fan motor. In a properly working air conditioner, the fan will draw air over the cold evaporator coils and then re-circulate the air back into the room. If the circulating fan is not running or running too slow, little or no air flow over the evaporator coils will allow them to become too cold and frost or ice can form, restricting the air flow even more. The fan and motor are located inside so removal of the cabinet will be necessary to perform any checks. Make sure that the fan motor will turn easily and that the blades are not damaged. If the motor is seized or if the fan blades are damaged then they will need to be replaced. If the motor turns easily it may still be defective or it may not be getting power from the controls. These tests are more complicated and should be performed by a qualified person who is comfortable with the use of a multi-meter.

Temperature Control

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If your air conditioner is not blowing cold air and you have inspected the air filter and fan motor and found them okay, then you may have a problem with the temperature control or thermostat. This is the device that monitors the incoming air temperature and turns the compressor on or off. There is normally a sensing bulb attached to the control that will extend to the front of the evaporator coil, and a set of electrical contacts in the body of the control that supply power to the compressor circuit. The bulb monitors the room air temperature and will tell the thermostat control to turn the compressor on when the set temperature is lower than the room temperature. The thermostat will also cycle the compressor off when the desired temperature has been reached. If the temperature control or thermostat is defective, it may not send power to the compressor, and no cooling will take place. Inspect the sensing bulb for any signs of a sharp bend, kink or rupture and replace the control if any are found. You can also check the continuity of the control with a multi-meter by rotating the dial to the lowest setting. Verify that the sensing bulb is properly located in the air flow through the evaporator coils before condemning the control.