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Error code reference
Goodman Heat Pump Error Code 01
Low side fault - low refrigerant charge, liquid line restriction, indoor blower motor failure, or indoor thermostat set extremely low.
SourceGoodman Heat Pump - Full Service Manual: GSX/GSZ Series R-410Ap. 82-83
Diagnostic procedure
The full 01 procedure
Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.
MyPros+ · DiagnosticsStep 1 preview
1
First diagnostic step
Verify refrigerant charge; adjust as needed. Check for restricted liquid line.
SourceGoodman Heat Pump - Full Service Manual: GSX/GSZ Series R-410Ap. 82-83
More steps, wiring diagram references, and verified part numbers
Includes expected resistance and voltage values, connector pinouts, and supersession notes for replacement parts.
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