Goodman GMVC960803BN Error Code EEF: Condensate Switch Open
What Does Code EEF Mean?
Error code EEF on the Goodman GMVC960803BN indicates that the auxiliary condensate switch (also called the condensate overflow switch) has opened. The furnace has stopped operating because the switch has detected a high water level in the system, typically in the evaporator coil drain pan or condensate piping.
As a high-efficiency condensing furnace, the GMVC960803BN produces condensate water as a normal byproduct of operation. This water is supposed to drain through a condensate trap and drain line to a floor drain, condensate pump, or other disposal point. When the drain path becomes clogged, water backs up and the overflow switch shuts down the furnace to prevent water damage.
The most common cause is a clogged condensate drain line or trap. Algae, mold, and sediment can accumulate over time and block the drain. The evaporator coil drain pan (if your system has one above the furnace) can also overflow if its separate drain is blocked. In winter, a frozen drain line to the exterior can cause this condition as well.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Clogged condensate drain line or trap | Most common | ✗ Call a pro → |
| High water level in evaporator coil drain pan | Most common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- The drain line remains clogged despite attempting to clear it with a shop vacuum
- Code EEF returns shortly after clearing the drain
- Water is leaking from the furnace cabinet or evaporator coil area
- The condensate pump (if installed) is not operating
- You suspect the condensate switch itself is faulty or sticking
Sources
✓ Verified against manufacturer service manual — March 2026