Goodman GMVM970803BN Error Code EA: Reversed 115 VAC Polarity
What Does Code EA Mean?
An EA code on the Goodman GMVM970803BN means the 115-volt AC power supply to the furnace has reversed polarity, with the hot (line) and neutral wires swapped. Proper electrical polarity is essential for the flame sensing circuit to function correctly. The flame rectification system this furnace uses relies on the electrical difference between the hot conductor and the grounded system to detect flame presence. With reversed polarity, flame detection is unreliable, so the control board refuses to operate as a safety precaution. The furnace will not produce heat at all while this condition exists.
This condition typically occurs after installation work or electrical repairs where the furnace power wires were reconnected with hot and neutral reversed. It can also happen if the outlet, junction box, or disconnect switch supplying power to the furnace was wired with reversed conductors. In some cases, a missing or poorly connected ground can produce a similar reading. The ComfortNet thermostat will display a "Call for Service" icon and scroll "Check Furnace" when this code is active.
Correcting reversed polarity requires work on 115-volt AC wiring, which should only be performed by a qualified electrician or HVAC technician. The technician needs to turn off the circuit breaker, identify the wiring connections at the furnace disconnect or junction box, and swap the hot and neutral conductors to restore correct polarity. After correction, the furnace should operate normally.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Polarity of 115 volt AC power to furnace or integrated module is reversed | Most common | ✗ Call a pro → |
| Reversed unit ground | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Call a qualified electrician or HVAC technician to correct the 115-volt wiring polarity at the furnace disconnect or junction box — do not attempt to work on line voltage wiring yourself
- The technician should verify proper grounding in addition to polarity, as a missing ground can also contribute to flame sensing failures on this model
✓ Verified against manufacturer service manual — March 2026