Goodman / Amana / Daikin · Air Conditioner error code

A2Outdoor air temperature sensor fault

Cross-checked Power off, standard tools

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Related diagnostic guides

Guide · Air Conditioner

Field pattern: heat pump runs nonstop in cold weather (normal long runs vs aux locked out or not wired)

Heat pumps lose capacity as it gets colder, and variable-speed units are designed to run almost continuously at low speed. Long runs are normal if the house holds setpoint. If the house falls behind, check whether aux heat is locked out too low, disabled by a compressor lockout setting, or not wired, before suspecting the refrigerant system.

7 steps ~45 minmoderate

Guide · Air Conditioner

Dual fuel (heat pump + gas furnace): changeover and balance point settings

In a dual fuel system the heat pump should heat down to a chosen outdoor temperature, then stop while the furnace takes over. The two should not heat together except during defrost, when the furnace tempers the air. Problems are almost always setup: wrong backup heat type in the thermostat, no outdoor temperature source, or a thermostat that does not support dual fuel at all.

7 steps ~45 minmoderate

Guide · Air Conditioner

Field pattern: big electric bill after a setback schedule (recovery brings on aux strips)

When the gap between room temperature and setpoint is large, most thermostats bring on aux strips to recover. Strips cost several times more to run than the heat pump, so a deep setback can wipe out its savings. Fix it with smaller setbacks, heat-pump-aware recovery, and an outdoor-temperature aux lockout.

6 steps ~30 mineasy