Goodman Heat Pump Error Code b6

Error code b6 on a Goodman heat pump indicates an over/under voltage trip or an over temperature trip within the system. This code is generated by the control board when it detects that incoming supply voltage has fallen outside acceptable operating limits, or when a temperature threshold within the unit has been exceeded. Voltage-related trips occur when line voltage drops significantly below or rises above the rated operating range of the heat pump, causing the control board to shut down operation to prevent compressor or component damage. Over temperature trips occur when internal temperatures reach unsafe levels, typically due to restricted airflow, refrigerant issues, or a failing component.

Voltage problems are often tied to utility supply fluctuations, undersized wiring, loose electrical connections, or a failing capacitor creating excessive current draw. Under-voltage conditions are particularly damaging to the compressor motor, as it will attempt to run with insufficient power, causing overheating and potential winding failure. Over-voltage can stress capacitors and control boards. Both conditions trigger b6 as a protective shutdown.

Over temperature trips associated with b6 can stem from dirty air filters, blocked coils, low refrigerant charge reducing heat transfer efficiency, or a malfunctioning fan motor that reduces airflow across the heat exchanger. Identifying whether the trip is voltage-related or temperature-related is the critical first diagnostic step. Checking supply voltage at the unit disconnect under load and inspecting airflow components will help isolate the root cause before any parts are replaced.