Whirlpool air conditioner displays E3 and may stop cooling or cycle off prematurely.

Safety: Unplug the unit. For window and through-the-wall models, be careful when accessing the outdoor section; the chassis is heavy.

How to troubleshoot E3:

• Remove chassis (if applicable): For some Whirlpool window units, you must slide the chassis out of the sleeve to access the outdoor coil and sensor. Follow the user manual for removal steps.
• Locate outdoor sensor: The outdoor thermistor is typically clipped to the condenser coil or mounted near the compressor in the outdoor compartment.
• Inspect physical condition: Check for broken sensor body, damaged insulation, or wires rubbed through on metal edges.
• Check wiring harness: Trace the sensor wires back to the control board. Look for loose or corroded connectors and reseat them.
• Measure resistance: With the unit unplugged, disconnect the sensor and measure resistance with a multimeter. Compare to Whirlpool specs for the given ambient temperature. Replace if open or shorted.
• Replace sensor: Install a new outdoor temperature sensor if faulty. Secure it firmly to the coil or bracket in the same location.
• Reassemble: Reinstall the chassis into the sleeve, secure all screws, and ensure the unit is level.
• Test operation: Restore power and run the unit in COOL mode. Verify that E3 is cleared and the unit maintains normal operation.

Call a technician if: Sensor and wiring test good but E3 persists, indicating a likely main control board failure.