No heat

[marc71]

Camping this weekend and it’s a bit chilly... went to turn the heat on and nothing! The fan kicks on for a minute or two and then shuts off. All the other gas fixtures are working properly. I crack the line open at the heater and there’s gas going to it. We just purchased the camper before Labor Day, it’s a 2014 Jayco Jayflight 32 BHDS. I’m not sure of the heater manufacture but the exhaust on the outside is a single round vent.

Any suggestions?

[larry_cad]

2oldman wrote:
Don't like to not be used...

Yes! Thank you. 🙂

[2oldman]

Don't like to not be used...

[mchero]

larry cad wrote:
Typically RV furnaces don't like to not be used for a long time. Too many things can happen.

I'm sure others will have additional ideas.

Odd statement, I have been full timing in my rig for the last 4 years and my two furnaces are still running strong, especially during the winter time.
I think lack of use is what causes the most problems. I do PM both furnaces each spring.

[drsteve]

The blower is inside the furnace housing, which just sits on a hole in the floor. The exhaust pipe slides into the outlet on the side of the furnace. Unscrew the furnace from the floor, unhook the gas connection, and pull the furnace out.

[marc71]

Thank you for the replies. I’m still without heat after checking what I can see, batteries are fine and propane is good, wire connections that I can reach are tight...it’s got to be something internal. I’ve been looking at the removal and it does not appear to be to difficult, my concern is how is the exterior vent attached and also how the blower is attached to the duct work?

[wa8yxm]

Alas the boiler plate is not present on this computer.

I've posted the diagnostic procedure in the past a search on "Furnace" may find it. But

1: THe t-stat calls for heat the blower starts
2: When it is up to speed (Air flow is high enough) a sail switch closes
3: The control board now opens the gas valve and starts sending sparks
4: It stops sending sparks and checks to see if the rod is hot (Flame detect)
5: If present heat continues till either the T-Stat says shut down or the HIGH-TEMP sensor shuts it down or you run out of gas.

1: Not your problem
2: Low batteries. blocked air flow bad motor bad sail swith
3: bad control board, bad gas valve, spark gap too wide, no propane
4: IF the switch from spark to sense goes wrong the sense chip gets hit nearly 1500 peak volts (It's looking for less than 1/2 volt) and pop goes the sensor.
Also bad thermocouple (The senor rod) or bad placement or clogged gas jet.

Mine was a bad control board.. If so Dinosaur boards

[zigzagrv]

I'm surprised no one mentioned low or weak batteries, which will not run the fan fast enough to activate the sail switch.

[corvettekent]

Our furness would not work in the morning when we first got up but would fire up a few hours latter when I was out trying to fix it. All the other propane stuff worked fine. Then the range started having a low flame so I replaced the propane regalator, now the furness works all the time.

[dougrainer]

The bad news is, you have to pull the complete furnace to troubleshoot and fix on your model furnace. The other bad news is, when you pull the furnace, odds are the jostling will reset the hi limit switch IF IT WAS the cause of no ignition. Sooo, When I have this type problem with a no access furnace, I take a rubber mallet and sharply pound on the inside burner casing area. Then try to restart the furnace. IF it then lights and stays lit, I pull the furnace and replace the Hi limit switch as it is sticking OPEN. Regardless, with a non accessable furnace when I pull for repair, I ALWAYS replace the Hi limit regardless of any other bad part is the problem. The Hi limit is not that expensive and cheap insurance to prevent a future problem caused by a intermittent hi limit switch. Doug

[2oldman]

Sounds like no propane.

[naturist]

Stink bugs. Probably dead now. Flippin' things get in everywhere, and one crawling into the burner tube of your furnace, water heater, grill, or other propane appliance will screw up the burn and result in just this problem. On the one hand, pulling the burner assembly out and blowing the bug(s) out is a cheap fix. On the other hand, it's a pain in the neck for sure. So before you fuss about the other issues above, look for stink bugs in the burner.

[drsteve]

The fan comes on first, if it's moving enough air then you should hear the igniter clicking. Is it trying to light?

[Dick_B]

At our age (81) we would call the nearest available mobile RV tech. About a year ago we had to replace the gas valve in our furnace.

[Dusty_R]

garyemunson wrote:
There is a "sail switch" that looks for airflow through the unit. If it is stuck (or bad), it will not allow the gas to turn on.

Or if something is blocking the air flow, the Sail Switch is doing it's job.

Dusty