Goodman Furnace: Check ECM motor windings
Check ECM motor windings on a Goodman furnace: This check looks at the three phase windings in the ECM motor for imbalance, an open winding or a short to the motor shell. It is done with an ohmmeter and the power off. Wait the full 5 minutes after disconnecting power before opening the motor, because the electronics can hold a charge. The windings should all read nearly the same. Anything unequal, open or touching the shell means the motor is done. Keep the readings written down, and handle the module and harness with care.
Applies to: ECM blower motors on ACVC96/AMVC96/GCVC96/GMVC96
Common causes of check ecm motor windings
- Unequal winding resistance between phases
- Open winding
- Winding shorted to the motor shell
- Moisture or contamination in the motor causing a leakage path
How to fix check ecm motor windings: step by step
- Disconnect power and wait 5 minutes
- Disassemble the motor as in the control/end bell check
- Measure resistance between each phase winding on the 3-circuit harness. The readings should be equal
- Replace the motor if resistances are unequal, open or shorted
- Measure resistance from each phase winding to the motor shell. Replace the motor if any winding is shorted to the shell
- Reassemble and reinstall the blower assembly
- Restore power only after confirming everything is back together, and verify operation
If the unit shows an error code, look it up: Goodman Furnace codes
Source: Goodman GMVC96 service and troubleshooting manual, p. 46. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.