Error code reference
Carrier Hvac Error Code 37
Heater output sensed on when not energized
Heater output sensed on when not energized — 24-Vac signal detected on electric heater stage 1 or stage 2 output when control is not supplying signal.
First step from the service manual
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.
The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.
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- Step-by-step tests with expected resistance, voltage, and continuity values
- Wiring diagram references and connector pinouts from the OEM service manual
- Verified part numbers when replacement is required
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