RV Repair: Atwood Furnace, gas valve, furnace

Question
I Have a Atwood 8535 III furnace. The problem is that when i turn on the thermostat, the fan comes on and runs for about 15 seconds and shuts off and then it will not turn on again. The thermostat is a Coleman heat/cool model.

Answer
Kenneth, Are you sure it is only 15 seconds? It should run about 45 seconds while it tries to light. It sounds to me like it is a board problem. The igniter board for that furnace operates the fan as well as opening the gas valve and lighting the furnace. I am not sure of the installation of your particular furnace but the board is located inside the housing that the furnace is in. Some open from the outside while others you have to pull from the inside. I would take the board off and have it tested at a shop. I think they will find out that it is failing. Thanks, Bill