furnace fixed (long)

[wingerphil]

I have had a nagging issue with my furnace on our 07 3400. I have read others with similier problems so thought I would share what I have found and the fixes I have done.
The problem seemed to occur when the drivers side tank went empty and the regulator switched over to the passenger side tank. The furnace would not ignite and the light (behind the outside access door to the furnace) would flash a code for "limit switch/air flow". The gas guage indicator on the regulator when switched to the passenger tank would show 1/2 red 1/2 green which seemed to be a flow pressure issue. I replaced the "red" regulator inside the passenger side tank compartment with a new one from Marshall which did not solve the problem.
I took the unit into Keystone while at the Fall Rally because the furnace would not even ignite when we tried it this fall. Low pressure was confirmed by the fine folks at the Service Center who tested it and found the pressure at 9 and it should be 11 (they adjusted the switch over regulator). They got the furnace working and all appeared well.

Night before last we woke up cold. The furnace was out again. I checked and confirmed the passenger tank was full and the regulator showed all green on the guage. I took the panel off and no trouble codes. There is a switch behind the outside panel so I shut it off and then turned it back on, furnace worked. Then my hand accidently brushed against the wiring to the switch and it shut down. They use a small blue wiring "clip" to connect the wires and this one was making a bad connection. I cut it off and put new, better ones on. There are 2 of these blue clips (one "in line" and one to a post on the switch) that you can see when you take off the outer panel. Both of mine were bad and you could shut the furnace down with just the slightest movement of the wires.

So far, so good. We woke up toasty warm this morning. I think the pressure adjust from Keystone corrected my "main" problem and getting lucky and finding the loose connections looks like it solved another, and hopefully last problem.

Phil

[Lambchop]

Thanks for the information, Phil....
I'll keep this one in the back of my head.



Roy & Kay

[dwstockman]

Glad you found the problem Phil. Hopefully it's your last problem with the furnace.

[sreigle]

Phil, I think you solved the problem. I say that because we had exactly the same problem about 2 years ago. I found it the same way as you except I was on the phone with the furnace people and they asked me to shut off that switch and turn it back on. I bumped the wires, as you did, and the fan started. As you know the fan must be up to speed before the furnace will fire. I then found I could turn the fan off and on at will simply by wiggling the wires. I located the bad connection and fixed it and have never had another problem since. Good job, Phil. Since ours is also a 2007 there must have been a spate of faulty connections about the time ours were built. Our Montana build date was 8/18/06.

[wingerphil]

Steve,
I think you may be on to something there. Our build date was September of 2006/