Goodman Air Conditioner Error Code F6

The F6 error code on a Goodman air conditioner indicates that the indoor discharge thermistor has reported a temperature reading that falls outside of the acceptable operating range. This thermistor, identified by its yellow wire coloring, is a negative temperature coefficient (NTC) sensor mounted at or near the indoor unit's air discharge point. Its job is to continuously monitor the temperature of the air leaving the indoor coil assembly and report that data to the control board so the system can regulate operation safely and efficiently.

When the control board receives a signal from the yellow indoor discharge thermistor that is either too high or too low to be a valid reading, it interprets this as a fault condition and triggers the F6 code. This typically happens when the thermistor's resistance has drifted out of the expected range, which can occur due to a failed or degraded sensor element, a wiring fault such as a short or open circuit in the thermistor leads, or a poor connection at the control board or sensor harness.

Because the first diagnostic step is direct replacement of the yellow indoor discharge thermistor, the sensor itself is the primary suspect. Before replacing, technicians should inspect the thermistor wiring for any visible damage, pinching, or corrosion at the connector. If the wiring checks out visually and with a continuity test, replacing the thermistor is the recommended corrective action. Leaving this fault unaddressed can prevent the system from operating correctly, as the control board relies on this sensor input to make key decisions about runtime and safety shutdowns.