Furnace runs no heat.

[VWFridolin]

Originally Posted by Larry-NC

Read Post #12 again.

It doesn't matter what the thermostat sounds like. Sit by the furnace (big return air grille) and answer these questions:
1) How long does the furnace blow before it quits?
2) Do you hear a clunk as the gas valve opens?
3) Do you hear a loud click-click-click or snap-snap-snap?

1)Maybe 7-10 min.
2)no clunk just a click and blower running nothing else happens after that. Runs 7-10 min shuts off.

[VWFridolin]

Originally Posted by MR.M

You need to be good with a meter . fans kicks on the shuts off first strp sail switch not making contact . need to check continuity while fan is running . if you have continuity through sail switch but still not ignition ie sparking click it could be high limit at the rear of heat exchanger. if you get continuity through sail switch when fan is running and hi limit has solid continuity and still no spark or smell of gas then control board . if you smell gas but not lighting flame then it could be control board , igniter . clogged exhaust from mud dubers etc .

I don’t own a meter but I can get one and check it. Where it’s my vent to see if it’s clogged.

[Larry-NC]

Originally Posted by VWFridolin

1)Maybe 7-10 min.
2)no clunk just a click and blower running nothing else happens after that. Runs 7-10 min shuts off.

That doesn't match any sequence in the manual. The manual with functional description and troubleshooting charts is here.

[WanderMore]

I bought a used popup a number of years ago at a very cheap price…it had become mouse infested. First time I tried the furnace it would not light off; good thing as there was an old mouse nest in it. Once cleaned out the furnace fired up like new.

[Attila the Pun]

We had that happen with our 2021 unit this spring. Fortunately we were still under warranty. Turned out to be a faulty igniter in the furnace. Once that was replaced we've had no issues.

[imjustdave]

simple check... I bet maybe your regulator has tripped. light 1 burner look at the flame... than light another did the flame change size?

turn off all propane, slowly like epic slow turn valve back on. if you hear a click... start over. once you get them on without a click check stove again. then try the heater. seen this way to many times.

[ghemmer]

If it is a Dometic, it could be the sail switch

[Larry-NC]

Originally Posted by imjustdave

simple check... I bet maybe your regulator has tripped. light 1 burner look at the flame... than light another did the flame change size?

turn off all propane, slowly like epic slow turn valve back on. if you hear a click... start over. once you get them on without a click check stove again. then try the heater. seen this way to many times.

That's not the regulator. That's the flow restrictor WITHIN THE PROPANE TANK. A lot of grill users think the flow restrictor is in the regulator, but it's not.

Regardless, the cure is the same.

• Turn off propane at the tank.
• Relieve pressure at the tank outlet by loosening the hose or turning on an appliance.
• Wait a bit.
• Tighten the hose or turn the appliance off to limit flow rate.
• Turn on the propane at the tank very slowly.

In the future, always make sure the appliances are off before turning the propane tank, thereby limiting the inrush flow and avoiding setting the safety flow restrictor.

[Midwest Ed]

When my furnace would not produce heat it was the Sail Switch as Larry-NC described. Blower runs but no fuel valve click after a few seconds. The Sail Switch verifies that the blower fan is running. It's a microswitch with an enlarged, flat "paddle" attached so the wind force can activate it. Any sort of contamination will foul it's operation, spider webs, mice, insects etc.

Rather than disassembling it I simply blew air into the outside exhaust port using my air compressor (horizontal chimney actually). This cleared the interference. I was careful as I was concerned too much compressed air force might damage the Sail Switch.

Another tip in checking the next step of the safety checking built into the furnace is to have a 2nd person assist so one of you can stand outside, very close to the exhaust port. If you can get a whiff of gas then the problem is the igniter. Otherwise, the problem is the fuel supply, i.e. fuel, fuel pressure, furnace fuel valve solenoid, etc.

This chart summarizes the troubleshooting steps quite well:
https://homearoam.com/how-to/rv-furn...leshooting.pdf

Now my thermostat just quit working today (I can bypass it with a jumper wire). Any suggestions for a simple 2 wire replacement?

[frankraney]

Originally Posted by VWFridolin

Hello All!! I have a 2006 Forrest River Surveyor 303. Having furnace issues. I have two full tanks of propane and the stove works fine. The thermostat will turn the heat on but it only blows cold air for serial minutes then shuts off. Not sure if I have a pilot light and where it would be to check it if so. We just bought camper to move into and got to get heat working. Any help would be appreciated. Thanks!!!

Is the valve at the furnace turned on. Does the igniter work. It out dose not, the supply will be turned off.

[REL]

It might just need a good cleaning after years of not being used. Mice, spiders, mud daubers. Had a similar problem with a gas fireplace. Turns out it was spiders causing the problem.

[Hustler]

Check ur gas line from the heater. It might have a crimp in it.

[strut526]

Had the same issue this fall with my 2005 American sport. Turned out it was the furnace breaker, I bought a new one at an rv place, but the guy told me I could of gotten one cheaper at a hardware..we had already replaced the thermostat, that wasn't it. But it did start working when the breaker was replaced.

[marvannet]

Sounds similar to what we experienced a couple of years back. Had to replace the circuit board.

[Civrel]

If you are sure that the gas is reaching the furnace and all wires are connected and fuses are good, there are a couple of possible causes:

First cause is the furnace burner pipe has a blockage. If the sail switch does not open all the way due to poor air flow, the burner will not ignite. Maybe a frog or wasp nest or mud dauber. Try blowing air into the burner tube with an air compressor. If nothing comes out, try a long (3’) pipe cleaner. Be careful do not damage the burner or sail switch with the pipe cleaner.

Second cause is dirt in the line behind the burner orifice. Remove the orifice to see if it is clogged. Maybe a metal shaving or a piece of sawdust. Blow out the gas line and see if any dirt comes out.

The furnace is usually fairly easy to remove, screws on the exterior and a couple holding the box in place, gas line, vent tubings and a dc power connection. It might be easier to work on outside the camper. Remember to shut the gas off before disconnecting.

[Rmack]

Originally Posted by VWFridolin

Hello All!! I have a 2006 Forrest River Surveyor 303. Having furnace issues. I have two full tanks of propane and the stove works fine. The thermostat will turn the heat on but it only blows cold air for serial minutes then shuts off. Not sure if I have a pilot light and where it would be to check it if so. We just bought camper to move into and got to get heat working. Any help would be appreciated. Thanks!!!

I had the same problem with my furnace a few years ago. It was the Chinese control board. The repair guy said a whole lot of them were failing.

[richardbrucewinquestjr]

Issues with the furnace depends on the brand along with age and other factors. Older furnaces which have a physical pilot you may want to replace the thermal couple but if it has electronic ignition then look at other factors as mentioned in earlier posts. Boards could be bad or thermostat, I’ve also taken gas lines off and found very small particles just behind the orfice so when the gas flowed the particles would blow around and plug the orfice hole. Try jumping the thermostat and see if that works or jump power to the igniter. Some furnaces mostly older ones have procedures to get going on the furnace access door and like other posts a good flashlight and close inspection on all systems ( intake, exhaust, thermostat and fuel. Sounds complicated but with careful inspection you can look at the components and figure out their basics. If you’re already camping ask some neighbors as you may also find someone willing to lend a helping hand or advice also at the furnace there may also be a on/off valve don’t be afraid to look closely at it.

[5picker]

Originally Posted by Midwest Ed

When my furnace would not produce heat it was the Sail Switch as Larry-NC described. Blower runs but no fuel valve click after a few seconds. The Sail Switch verifies that the blower fan is running. It's a microswitch with an enlarged, flat "paddle" attached so the wind force can activate it. Any sort of contamination will foul it's operation, spider webs, mice, insects etc.

Rather than disassembling it I simply blew air into the outside exhaust port using my air compressor (horizontal chimney actually). This cleared the interference. I was careful as I was concerned too much compressed air force might damage the Sail Switch.

Another tip in checking the next step of the safety checking built into the furnace is to have a 2nd person assist so one of you can stand outside, very close to the exhaust port. If you can get a whiff of gas then the problem is the igniter. Otherwise, the problem is the fuel supply, i.e. fuel, fuel pressure, furnace fuel valve solenoid, etc.

This chart summarizes the troubleshooting steps quite well:
https://homearoam.com/how-to/rv-furn...leshooting.pdf

Now my thermostat just quit working today (I can bypass it with a jumper wire). Any suggestions for a simple 2 wire replacement?

Interesting.
I've never seen the sail switch mounted within the combustion side of an R/V furnace.
What make/model was this?

Blowing compressed air in the exhaust chimney would never reach the sail switch as the combustion side of the blower and the room air side of the blower (where the sail switch is typically located) are isolated from each other.

[elob_tx]

If there was no screen over the outside exhaust for the furnace when you bought it I would suspect that some wasps or mud daubers or other insect may have plugged up the exhaust so even if the sail switch is good it detects no flow through the furnace to allow the igniter to be called on to start combustion after the purge cycle completes. Then the furnace turns off and will try a couple more times before locking out. Cycle the power off and on and you can try again but if the exhaust is restricted you get the same result. This is not an uncommon occurrence. Why these furnaces don't come with insect screens is hard to understand. They aren't expensive to add and solve these problems.

[rdolan5]

Two possibilities I would check. If the heater comes on but won't heat the air, and then shuts down after a short period of time, The propane regulator on the bottle not putting out enough pressure so the heater won't open the solenoid for gas flow on the furnace. If the heater won't even turn on. Either the board on the heater or time for a new thermostat inside the trailer.