How to Replace a Window Air Conditioner Ambient Thermistor

 

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This DIY repair guide explains how to replace the ambient thermistor in a window air conditioner. The ambient thermistor is a sensor that detects the room air temperature so the electronic control board can regulate the room temperature. If the thermistor isn't working, the air conditioner won't maintain the temperature you set. Replace a malfunctioning ambient thermistor with the manufacturer-approved replacement part.

Repair difficulty:
     
Time required:

Less than 45 min.

Parts Required

  • Ambient thermistor

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

Tools Required

  • Phillips screwdriver
  • Work gloves

Before you begin

Wear work gloves to protect your hands.

Instructions

 Warning: Undertaking repairs to appliances can be hazardous. Use the proper tools and safety equipment noted in the guide and follow all instructions. Do not proceed until you are confident that you understand all of the steps and are capable of completing the repair. Some repairs should only be performed by a qualified technician.

Step 1: Disconnect electrical power

Unplug the power cord from the wall outlet.

Step 2: Pull the air conditioner out of the window

Remove the screws that hold the accordion filler panels in the window frame. 

Push the accordion filler panels inward to clear the window frame.

With someone’s help, support the air conditioner and raise the window sash.

Carefully lift the air conditioner out of the window and set it on a stable work surface.

 

Step 3: Remove the front grill panel and filter

Grasp the sides of the front grill panel at the top and pull the front grill panel out and off of the air conditioner.

Pull the filter out.

 

 Tip: Take this opportunity to clean the air filter if necessary.

Step 4: Remove the control panel

Remove the screws from the sides and bottom of the control panel.

Pull the control panel up and hold it above the air conditioner. Unplug the wire harness connection for the user interface control board.

Set the control panel aside.

 

Step 5: Remove the front panel

Remove the screws from the sides of the front panel.

Pull the front panel off of the air conditioner and set it aside.

 

Step 6: Remove the outer case

Remove the screws from the exterior of the outer case. 

Remove the center stop for the accordion filler panels. Remove the hidden screw that is under that center stop.

Pull outward on the bottom of the outer case and remove the outer case from the air conditioner.

 

Step 7: Remove the ambient thermistor

Remove the screws from the electronic control board case. Pull out the cover of the electronic control board case to expose the electronic control board.

Disconnect the black ambient thermistor wire from the T1 connector on the electronic control board.

Pull the ambient thermistor out of the mounting clip on the front of the evaporator.

 

Step 8: Install the new ambient thermistor

Insert the new ambient thermistor in the mounting clip on the front of the evaporator.

Plug the wire harness for the ambient thermistor into the T1 connector on the electronic control board.

Position the cover of the electronic control board case in place and reinstall the screws.

 

 Tip: Make sure that wires aren’t pinched when reinstalling the electronic control board cover.

Step 9: Reinstall the outer case and front panel

Position the outer case properly on the air conditioner. 

Reinstall the screws in the outer case including the hidden screw in the center.

Position the front panel on the air conditioner and reinstall the mounting screws on the sides of the front panel.

 

Step 10: Reinstall the control panel

Position the control panel above the air conditioner and plug the user interface control wire harness back in.

Position the control panel on the front of the air conditioner and reinstall the mounting screws in the control panel.

 

Step 11: Reinstall the front grill panel and filter

Insert the filter on the front of the air conditioner.

Position the front grill panel on the front of the air conditioner and snap the front grill panel into place.

 

Step 12: Restore the power

Plug the air conditioner into the electrical outlet.