GE window or through-the-wall air conditioner stops cooling and displays E1 on the control panel

Safety first: Unplug the air conditioner from the wall outlet before removing any covers. Capacitors can hold a charge; avoid touching exposed terminals.

Step-by-step checks:

• Power reset: Unplug the unit for 5 minutes, then plug back in and try again. Sometimes E1 is a temporary logic fault.
• Access the control compartment: Remove the front grille and the control panel cover (usually a few Phillips screws). Carefully pull the control panel forward.
• Locate the room thermistor: On GE units, the ambient sensor is typically a small probe on thin wires near the front air intake or behind the control panel, plugged into the main control board.
• Check connections: Ensure the thermistor plug is fully seated on the control board and that no wires are pinched, cut, or corroded.
• Inspect the sensor: Look for physical damage, broken insulation, or corrosion. If damaged, replace the room temperature sensor (thermistor) with a GE-compatible part.
• Resistance test (optional): With the unit unplugged, disconnect the thermistor and measure resistance with a multimeter. At room temperature (~77°F / 25°C), most GE thermistors read around 10kΩ (check service manual for exact spec). If reading is open, shorted, or far off spec, replace the sensor.
• If sensor tests good: The main control board’s sensor input may be faulty. Inspect the board for burnt spots or corrosion. If present, replace the main control board.

When to stop: If you are not comfortable testing electrical components or removing the control panel, contact a qualified technician.