Goodman Air Conditioner Error Code F1

F1 on a Goodman air conditioner means the Indoor Ambient Thermistor is reading a temperature outside the valid range of -20°F to 200°F. This indicates the sensor may be faulty, disconnected, or shorted. On systems with a wireless thermostat, a simultaneous loss of communication with that thermostat can also trigger this code. The system flags F1 to prevent it from making control decisions based on an invalid temperature reading.

A power reset may temporarily clear the F1 code, but it will return if the underlying fault with the thermistor or wireless thermostat has not been corrected. Resetting the unit does not fix a failed sensor or a broken communication link. The fault must be diagnosed and repaired to permanently resolve the code.

If only the Indoor Ambient Thermistor needs replacement, parts and labor typically fall in the range of $75 to $200 depending on the technician's rates and your location. A wireless remote thermostat replacement can range from $100 to $300 or more, depending on the specific model required. If the control board is at fault, repair costs can be considerably higher, generally in the range of $250 to $600 or more.

A knowledgeable DIYer can inspect the thermistor wiring connections and check wireless thermostat batteries without special tools. If the wiring looks intact, testing the black IAT sensor with a multimeter to check its resistance can confirm whether it has failed. Replacing the thermistor or wireless thermostat is a straightforward repair, but if the control board is suspected, professional diagnosis is recommended.

Operating the system while F1 is active is not advisable because the control board lacks a reliable indoor temperature reference. Without accurate ambient temperature data, the system cannot make correct decisions about heating or cooling cycles. Continued operation could result in inefficient performance or improper control responses.