[onewhippedpuppy]

So with the help of the Pelican BBS, I managed to resolve my A/C issue. Now my heater downstairs is giving me trouble. It's a 19 year old Coleman 70, traditional natural gas forced air furnace. At some point it's had a Robertshaw ignition controller retrofitted, I assume probably to convert it from a pilot-light burner to automatic ignition.

Anyway, when commanded by the thermostat it fires up as it should, but once the fan kicks on the trouble starts. Typically, I can hear the relay in the Robertshaw ignition controller click, the burner will flicker, and the fan won't start. Sometimes this clicking and burner flicker will occur several times, then the burner will shut off and the fan will start. Other times, the ignition controller will click and everything will shut off. Sometimes the fan will start after a long delay (1 min or so). Sometimes the burner will re-fire while the fan is running, and work as usual. Other times the unit will shut-down entirely, and not re-fire until the power or thermostat is reset. This can lead to a chilly house.

Summary: the unit seems incapable of heating up and running the blower motor for an extended period of time, and can't seem to start the blower motor while the gas is still burning on initial start-up.

My first instinct was the gas valve, but it seems to be working as commanded by the ignition controller. So now my #1 suspect is the Robertshaw ignition controller. What say you Pelican braintrust?