Lennox Air Conditioner Error Code E180

E180 indicates that the outdoor unit ambient temperature sensor has malfunctioned. The outdoor control board is not receiving a valid resistance signal from the sensor, so it cannot accurately determine outdoor air temperature. As a direct result, the system disables low ambient cooling operation until the fault is corrected.

The system can continue to operate in standard cooling mode with E180 active, but low ambient cooling protection is disabled. Running the unit without this protection during low outdoor temperatures could potentially stress the compressor or refrigerant circuit. It is advisable to have the fault repaired promptly rather than continuing to run the system with a known sensor fault.

Repair costs vary depending on what component has failed. If only the ambient temperature sensor pack needs replacement, parts and labor typically range from around 80 to 200 dollars. If the outdoor unit control board has also failed, total costs can rise to a range of 300 to 600 dollars or more depending on the specific model and local labor rates. Getting a diagnostic assessment from a certified technician is the best way to estimate the actual cost for your unit.

Diagnosing E180 requires comparing the sensor's measured resistance to a temperature/resistance chart and testing wiring continuity, which requires a multimeter and familiarity with HVAC electrical systems. Checking and reseating connectors is within reach for a knowledgeable DIYer, but sensor replacement and control board diagnosis are typically best handled by a certified technician. Improper repairs could cause further damage to the control board or refrigerant system.

A power reset may temporarily clear E180 from the display, but the fault will return if the underlying sensor or wiring problem has not been corrected. The control board will re-detect the out-of-range resistance signal during normal operation and set the code again. A permanent resolution requires testing and repairing or replacing the defective component.