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Error code reference
Carrier HVAC Error Code 37
Heater output sensed on when not energized: fan coil control detects a 24-Vac signal on electric heater stage 1 or stage 2 output when it is not supplying signal.
SourceCarrier Fan Coil Units - Service Manual: FB/FE/FF/FH/FV/FX/FZ/PF Seriesp. 14
Diagnostic procedure
The full 37 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
Stop all system operations at User Interface and check heater stage 24-Vac outputs. Disconnect electric heater at plug/receptacle 2 and check heater wiring for faults.
SourceCarrier Fan Coil Units - Service Manual: FB/FE/FF/FH/FV/FX/FZ/PF Seriesp. 14
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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