Another furnace question....

[Linehand13]

Hey guys, new to the forum and I’ve been searching all day for answers, but nothing seems to match what we’re dealing with 100 percent....

We bought a ‘19 377 rlbh, and we’re having an issue in the furnace. With the thermostat set to 68, the furnace will not start up unless reset, by that I mean I turn it off for several minutes, turn back to heat, and the blower starts, runs the cycle and shuts down. No ignition. I’ve checked the magic reset switch(continuity), I’ve checked the sail switch(continuity), and voltage(12v). I haven’t check the high temp relay as I ran out of day light. Any light shed would be huge. We’re in northern nv @ 6200 feet. It’s blowing down snow and we’re here for a while. Also, if I shut down the 12 volt supply and fidget with the sail switch, I can get the furnace to operate until it reaches the desired temp but is dead in the water after

[Grumpy]

Originally Posted by Linehand13

We’re in northern nv @ 6200 feet. It’s blowing down snow and we’re here for a while.

There are numerous comments on the web about high altitude problems across many different RV brands.

[Route 66 Traveler]

Make sure you have good propane flow...turn on your stove and let it run or a minute or two. If there isn’t a good flow to the furnace it will try to lite, then shut down if the burner doesn’t ignite. Also, when opening the valve on the propane tank turn it slowly; turn it too fast and the internal safety will stop the flow of propane.

Has your furnace ever worked??

[Linehand13]

We have good flow, I’ve bled the system as you stated and still no ignition. The furnace was working up until two days ago. I was intermittent and last night just up and quit on us. Like I said, I can pull the heater apart and clean the contact in the sail switch and breaker switch. And get one good heat cycle out of it then it’s back to square one....

[Linehand13]

That was what I’ve been reading but it was working fine until a couple nights ago....

[Rustic Eagle]

Assuming the sail switch, high temp switch, and LP flow are good..., it leaves the circuit board and wall thermostat

Have you checked that the furnace has good return air flow to it? Some 5th wheels have a return air vent at the bedroom/bath steps and may also have a filter...., just a thought.

Bob

[RPR]

Had to buy a sail switch while on the road from a dealer two years ago. Parts guy had a tech come up to the counter and he said bend the sail part of the switch just a little and switch will last longer. Catches air better.

[JimD]

You mentioned that there was no ignition. Does that mean there is no sparking or does it mean sparking but no flame?

If it isn't sparking the problem is in the sequence before ignition is to start or there is a problem in the sparker (gap?). If it sparks but doesn't light, the problem is in the next phase of operation which is gas valve opens and gas flows then lights.

Attached is some info from the manual.

[Linehand13]

You mentioned that there was no ignition. Does that mean there is no sparking or does it mean sparking but no flame?

If it isn't sparking the problem is in the sequence before ignition is to start or there is a problem in the sparker (gap?). If it sparks but doesn't light, the problem is in the next phase of operation which is gas valve opens and gas flows then lights.


If I turn the thermostat to off, then return it to heat, the blower will start and run for 15 seconds or so..... and turn off with no ignition. It won’t even try, as stated in the manual. But if I go out and completely disconnect the 12volt source, pull the sail switch and blow on it or fidget with it, reinstall, and turn power back on, turn the thermostat to heat, I get one solid heat cycle and nothing after. It’s very confusing to me

[RPR]

Replace the sail switch

[JimD]

When you shove it back in is it possible something falls into the sail switch area preventing it from moving? Thinking outside the box.

You checked the sail switch for continuity. Was there any resistance measured when closed? Did the switch move freely? Does the sail move very freely? Any possible restriction in the air flow?

Sure sounds like the problem is in the blower sensing area. Is there any way of firing it up while looking inside for switch operation?

Love these kinds of problems that go away after you open them up only to return.

[Linehand13]

The switch and in side the blower were clean, I’m hoping that I can get the switch tomorrow and we’ll be back in business.... I sure appreciate all of the input! It’s way to damn cold here to be in the predicament... lol

[Linehand13]

Well, we’ve made progress and it’s trying to do the three cycle and shutting down....

[ALJO]

The Atwood furnaces with the sail-switch at the front of the blower we had more problems on late models RV's - most solutions where bending the fan to give it better lift. In one case it was the micro-switch. The electronic board is all about timing and any error will be reported in flashes to determine which circuit did fail. If one doesn't have a clear view on the flash LED's remove the furnace and bench test.

[steveajohnson]

Hello Lindhand, my furnace in a Pinnacle has similar issues, I reset switch, turn on furnace which runs fine thru one cycle then trips reset switch again. Did you find an answer?? Thanks Steve

[Linehand13]

Originally Posted by steveajohnson

Hello Lindhand, my furnace in a Pinnacle has similar issues, I reset switch, turn on furnace which runs fine thru one cycle then trips reset switch again. Did you find an answer?? Thanks Steve

Hey Steve, so my situation as stated above was a ton of trial and error..... obviously same as you I’m sure, I’d fumble with the sail switch and reset and get one solid heat cycle. What it needed up being was the high temp sensor. I have a friend that is a rv tech at a local dealer here in Reno NV, and that was the last guess before a bench test. My circuit board wasn’t throwing any flashes to indicate error and the ohm test through the new and old sail switch proved to be around the same. So I’d replace the high temp sensor and see if it fixes your issue. After replacing mine, it’s work famously and my family and I are nice and warm.