Window Air Conditioner: Won't start

If the window air conditioner has electrical power—the control panel powers up—but the compressor and fans won't run, possible causes include an electronic control failure or a wiring problem. The window air conditioner also won’t start if the electronic control detects a component problem such as a defective thermistor. Check the control panel for an error code, which usually indicates which component failed. To decipher an error code, check our error code tables or refer to your owner’s manual. Some repairs that could correct the problem are listed below.

These repairs may help solve your Window Air Conditioner problem:

Replace the window air conditioner control thermostat

Control thermostat

Some window air conditioners have an electro-mechanical thermostat instead of an electronic control board to control the on/off cycling of the compressor and fans. Replace the thermostat if it fails to control the compressor and fans properly.

For manuals, repair guides, and specific part recommendations, enter your model number.

Replace the window air conditioner electronic control board

Electronic control board

The electronic control board regulates the compressor, evaporator fan and condenser fan in the window air conditioner. If the electronic control board doesn’t activate those components properly, replace the control board.

For manuals, repair guides, and specific part recommendations, enter your model number.

Replace the window air conditioner user interface control board

User interface control board

The user interface control board in the control panel houses the selection buttons you push. A wire harness connects the user interface control board to the control board. If the selection buttons don’t respond when you push them, replace the user interface control board.

For manuals, repair guides, and specific part recommendations, enter your model number.

Replace the window air conditioner ambient thermistor

Thermistor

The window air conditioner ambient thermistor—also known as a temperature sensor—senses the temperature of the air entering the air conditioner and communicates that temperature to the electronic control board, which cycles the compressor on and off to maintain the set room temperature. The ambient thermistor is attached to the evaporator coil that’s behind the air filter, and a wire harness connects the ambient thermistor to the electronic control board. If the ambient thermistor is defective, the electronic control board will not cycle the compressor on and off properly to maintain the room temperature that is set on the control. Replace the ambient thermistor if it doesn’t accurately measure the ambient room temperature.

For manuals, repair guides, and specific part recommendations, enter your model number.