Hi Very similar problem to others I have seen here but mine appears to be little different. Glow bar would light up but the burner would not ignite. Found that what I believe to be a limit switch, there are four of them, 1 on each side of the enclosure that holds the burner tubes, is engaging. It is the one on the top of the enclosure. I reset the switch and the burner will come on for about 5 minutes then shuts down. The switch has engaged again. I don't know what is causing it to engage. I have seen the posts about clogged tubes, fans, filters and that all appears ok. The one thing I have observed that i have not seen, I could be blind, is that the burner tube next to the glow bar seems to be getting too much gas. On that particular tube the flame gradually gets bigger to the point where it is going up out the box and into the void space above. It does not directly touch the switch up there but it is in the area, about 6 inches away. So it appears the limit switch is doing its job, I don't really know what it is supposed to do. I guess my question is why is the burner tube on the left getting too much gas? And how can I remedy it. Thanks[ATTACH]41160[/ATTACH] BTW The flame starts getting out of control when the blower motor kicks in. I also had a problem with the AC drain tube being clogged this summer, but I don't THINK this is the issue as the furnace has run fine for a month.

Pilot lights fine, and will stay lit on its own for about 1-2 minutes, then off. Furnace itself lights up fine, will generate heat ... for about the same 1-2 minutes. 1) tried 3 different thermocouplers (different brands) 2) bypassed rollout switches 3) new air filter Furnace was turned off (including pilot) for most of a year. Hoping there is something to 'clean' as a means to fix? May be the gas valve itself, however want to isolate and know for certain before replacing (as the furnace is older, special order and an expensive part.) Seems as though it might be something else, however, given the entire system will fire up and work w/a hitch for those 2 minutes. Thoughts? Thank you in advance... -pr Details: - Borg Warner furnace - White Rogers gas valve model 36c03 (type 251)