# Furnace Won't Light



## Edward G (Oct 30, 2011)

I have a coachman 34 foot fifth wheel. I tried to start the furnace the other night, it would not light. it is a Coleman and has an igniter. I turned the thermostat on and then the gas. The blower would kick on immediately and then the igniter would lite for a few seconds and then go out. Any ideas what to check or where to start. Stove and fridge all work and have plenty of propane.


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## OutbackerTim (Oct 5, 2011)

I'd make sure the gas was on before turning on the furnace. You make have a thermocouple on the pilot that needs to get hot before it stays lit. I have this on my water heater when I use the propane to heat it. I just turn it on/off a few times, then it lights and catches, staying on. Only other thing is to make sure the exhaust venting isn't blocked by any debris/bug nests.


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## Insomniak (Jul 7, 2006)

There could be a number of reasons why the furnace won't light. Make sure you definitely have enough propane. Some devices will work with low propane pressure, while others like the furnace won't. Also, make sure that the gas line to the furnace is purged of air. Since you're getting a spark, it sounds like the sail switch and airflow are ok. If you're sure that the igniter is sparking, it may have become dislodged and isn't in the correct spot, or the spark isn't good enough to cause ignition. There may be rust or spider webs in the burner or gas valve orifice. Listen to the furnace outside where the vents are. You should hear the ticking of the igniter, followed by a "clunk" of the gas valve opening. If you don't hear the gas valve, it could be bad, or it may be the circut board. Unfortunately, most of these situations require pulling the furnace out and testing it on a workbench.


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