April 20, 2023

Window Air Conditioner: Why your window AC compressor is not turning on?

If the window air conditioner's compressor and fans are running but the air conditioner isn't cooling, possible causes include a failed compressor or the lack of refrigerant due to a leak in the sealed system.

If the compressor isn't running but the fans work, the start relay or compressor might have failed.

A defective electronic control board or control thermostat could prevent the window air conditioner from cooling.

If the window AC compressor is not staying on, then the compressor is likely overheating.

Follow these steps to prevent the compressor from overheating:

Clean the condenser coils so refrigerant cools down properly when the compressor runs.
Check the condenser fan blade and replace the blade if it's damaged.
Clean all air vent slots in the window AC cabinet to maintain cooling air flow going to the compressor.

If the window AC compressor is not staying on after following these troubleshooting steps, then you may need to replace the compressor.

THESE REPAIRS MAY HELP SOLVE YOUR WINDOW AIR CONDITIONER PROBLEM

Replace the window air conditioner 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.

Window air conditioner electronic control board

Find the required part specific to your product.

January 05, 2014

By Lyle Weischwill

How to replace a window air conditioner electronic control board

When a window air conditioner won't cool or won't start at all, the electronic control board might be the problem. This step-by-step repair guide shows how to replace a window air conditioner electronic control board.

Repair difficulty

Time required

45 minutes or less

Replace the window air conditioner compressor

The compressor is a pump that compresses the refrigerant-Freon-that's sealed in the window air conditioner. If the compressor doesn't run when activated, have a refrigerator service technician replace it; by law, an EPA-licensed technician must do this repair because it involves Freon.

Window air conditioner compressor

Find the required part specific to your product.

Replace the window air conditioner 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.

Window air conditioner control thermostat

Find the required part specific to your product.

Replace the window air conditioner evaporator thermistor

The evaporator thermistor is a temperature sensor that is mounted on the evaporator. It monitors the temperature of the evaporator to detect excessive frost on the evaporator. The thermistor communicates that temperature to the electronic control board through a wire harness connection. If the evaporator frosts up, the electronic control board will detect the frost according to the temperature communicated through the thermistor. If the thermistor is defective, the electronic control will not properly detect and eliminate the frost. Replace the evaporator thermistor if it doesn't properly detect the evaporator temperature.