HVACopediaGoodman · Furnace troubleshooting
Check ECM low voltage control circuit
What is going on
Low voltage side of the ECM. Checks the DC control signal between the control board and the motor.
Likely causes
- No control signal from the board to the motor
- Loose or damaged 4-wire motor control harness
Check in this order
- Power on, motor harness connected.
- Meter set to DC volts, because this signal is DC and AC will read wrong.
- Measure between pins 1 and 4 on the 4-wire motor control harness. It should be 3 to 15 VDC.
- No voltage? Go to the control board check, see section S-313.
- If the board is putting out the signal and the motor stays off, move on to the motor itself.
Applies to: ECM blower motors on ACVC96/AMVC96/GCVC96/GMVC96
More furnace guides
- Airflow lower than demanded, furnace runs on low stage when high stage is expected
- Alternate combustion air opening (upflow or horizontal)
- Alternate vent/flue location (upflow or horizontal left)
- Annual inspection checklist
- Auxiliary limit control (location and purpose)
- Auxiliary limit switch open (blower compartment)
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Source: Goodman GMVC96 service and troubleshooting manual, p. 46. Written in our own words; check the manual for your exact model.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.