2 GREEN FLASHES
Coleman
Low-Voltage Fuse Open or Short in Thermostat Circuit
Status LED flashes green twice repeatedly; blower may run briefly; furnace does not heat.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Blown 3–5A fuse on control board, Shorted thermostat wire to ground, Shorted humidifier or accessory connected to R/C, Miswired outdoor unit low-voltage circuit
How to Fix / Troubleshooting
Safety first: Turn off power before replacing fuses or handling low-voltage wiring.
Steps to check:
- Inspect and replace fuse: Locate the automotive-style fuse on the Coleman control board. If blown, replace with the same amperage rating.
- Isolate circuits: Before restoring power, disconnect thermostat wires from the board (R, W, Y, G, C). Restore power. If the fuse holds, reconnect one wire at a time until the fuse blows again. The last wire connected indicates the shorted circuit.
- Inspect wiring run: Follow the suspect wire from furnace to thermostat or outdoor unit. Look for insulation damaged by staples, metal edges, or rodents. Repair or replace as needed.
- Check accessories: If a humidifier, air cleaner, or outdoor unit is powered from R/C, disconnect it and test again. Faulty accessories can short the low-voltage circuit.
Do not install a larger fuse than specified; this can damage the control board and transformer.
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Repair Difficulty
Medium
3/5
Required Part
Low-Voltage Fuse
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