Goodman GMVC960803BN Error Code EE5: Open Fuse
What Does Code EE5 Mean?
EE5 on the Goodman GMVC960803BN means the board's 3-amp low-voltage fuse has opened. This fuse protects the 24VAC transformer and the integrated control module from excessive current, and when it blows the furnace loses all 24VAC control power and stops.
The fuse rarely fails on its own — it is a symptom of a short circuit somewhere in the 24V system. The short can be internal to the furnace or external in the thermostat and accessory wiring. Common culprits are a pinched or chewed thermostat wire, a damaged wire rubbing against sheet metal, or a shorted 24VAC accessory such as a humidifier, air cleaner, or zoning board. This makes EE5 a close relative of the other low-voltage and wiring faults on this board, such as EEA (reversed line polarity) and E10 (grounding fault), which also come down to wiring integrity.
Goodman's instructions call for locating and correcting the short, then replacing the fuse with a 3-amp automotive type. Replacing the fuse alone without clearing the short simply blows the new one immediately.
What You'll Notice
- The furnace is completely dead because the 24V control circuit has lost power
- The 7-segment display shows EE5, or is blank if the board itself lost power
- The furnace does not respond at all to the thermostat
- The failure often begins right after a thermostat swap, an accessory install, or rodent activity near the wiring
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Short in low voltage wiring (internal or external) | Most common | ✗ Call a pro → |
| Blown 3-amp fuse on control board | Most common | ✗ Call a pro → |
How This Is Diagnosed
A technician isolates the short by disconnecting each 24VAC load one at a time — thermostat wiring, humidifier, air cleaner, and zoning equipment — then restoring power to see whether a fresh 3-amp fuse holds. The circuit that causes the replacement fuse to blow contains the short, which is then traced and repaired before the final fuse is installed.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- The short must be located and repaired before a new fuse can hold — replacing the fuse alone will not fix the problem
- The short is suspected in thermostat wiring inside walls or at junction boxes, requiring professional tracing
- A 24VAC accessory such as a humidifier, UV light, or zone board is the source and must be properly repaired or replaced
Frequently Asked Questions
Can I just replace the blown fuse myself?
Replacing the fuse without finding the short will blow the new fuse immediately, and safely locating a low-voltage short takes a technician's tools and method. This is not a reliable DIY repair.
What causes the fuse to blow in the first place?
A short somewhere in the 24V wiring — most often a pinched thermostat wire or a faulty accessory. It is closely related to the other wiring faults on this board, such as EEA and E10. Repair cost depends on where the short is and varies by region.
✓ Verified against manufacturer service manual — March 2026