Thor Forums

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When you say the FAN runs, are you talking about the AC fan of the FURNACE fan? You cannot turn the furnace fan on with the thermostat, you can only call for the furnace to deliver heat. When that happens, the furnace fan will start and begin pushing air. Once the sensing device knows that air is moving it will signal the propane valve in the furnace to open and the igniter to start sparking to ignite the propane. It will try this 3 times before it times out if it doesn't sense the burner is lit. You can reset it with the reset switch as described above, wait 30 to 60 minutes for it to time out and reset itself to try again, or turn the furnace off at the thermostat fo a minute and then turn it back on again.

Lots of Thor motorhomes have problems with the control board getting wet and interfering with the furnace operation. You can check that by removing the same outside panel that gives you access to the reset switch. The circuit board is right below it. Check the bottom of the circuit board for moisture, you can remove it with one screw.