Get free shipping on your order, with any water filter subscription. Find my filter

Open Hamburger Menu
Sears Parts Direct
Please enter one or more characters
Scan Icon
Tips to find your model number
Water filters
Water filter finder tool
DIY help
Featured products
Top brands
View all parts by brand
Top products and services
Products by brand
Orders
Customer Service
Schedule a repair

Why are my window air conditioner's evaporator fins iced up?

less than a minute readJun 04Lyle Weischwill
image of room-air-conditioner

The evaporator fins on a window air conditioner ice up if the compressor runs constantly for one of these reasons:

  • A dirty air filter restricts air flow.

  • The air conditioner is too small for the room.

  • The temperature setting is too cold.

  • A control is defective.

See the repairs below to help correct a problem with evaporator finds that ice up.


These repairs may help solve your room-air-conditioner problem

JC-WAC-Replace-the-window-air-conditioner-ambient-thermistor

Replace the window air conditioner ambient 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.

Window air conditioner ambient thermistor

Find the required part specific to your product.
May 01
By Lyle Weischwill
How to replace a window air conditioner ambient thermistor

If your window air conditioner isn't cooling the room very well, the ambient thermistor might be at …

Repair time and Difficulty

 45 minutes or less
JC-WAC-Replace-the-window-air-conditioner-electronic-control-board

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.
Jan 05
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 b…

Repair time and Difficulty

 45 minutes or less
JC-WAC-Replace-the-window-air-conditioner-control-thermostat

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.
JC-WAC-Replace-the-window-air-conditioner-evaporator-thermistor

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.

Window air conditioner evaporator thermistor

Find the required part specific to your product.