Furnace Problem

Andy Vidra · 09-18-2017, 09:29 AM

I have a 2007 2553 trailer. On our most recent trip, the furnace worked one day and stopped working after that. The air conditioner works. The fan works. Just not the furnace. I checked the 15A fuse and it looks fine. I swapped it out with another fuse just to be sure. The furnace fuse worked in another slot. I took off the external cover and turned the on/off switch to off. I waited a while and turned it back on. No effect on getting the furnace going. Any ideas on what is wrong? (I did set the thermostat on its highest setting when I tried tturning the furnace on.)

**PTHutch** · 09-18-2017, 09:51 AM

Hi Andy,

I have to ask the obvious first:
> Do you have your LP tanks turned on?
> Do you have propane in the LP tanks?
> Did you try a stove top burner to see if that is working?

When you turned on the furnace, did you hear a clicking sound?
This is the electronic ignition trying to light the furnace.

Andy Vidra · 09-18-2017, 10:20 AM

Propane is ine. We used the stove and oven for a week after the furnace quit.

There is no click when I turn on the furnace. Essentially, nothing happens when I turn the it on. That holds true even when it is let on for a couple of hours or more.

**JohnB** · 09-18-2017, 11:57 AM

Hi Andy,

On your furnace, there is a starting and run sequence to them and we need to sort out where in that sequence something does not work.

Tell us what does or does not work and we can dig deeper from there.

1. Make sure power is on the camper. This can be just the battery turned on or the power converter plugged in. Make sure a light works in the camper to confirm.

2. When you turn the T-stat to heat and turn the temperature up so the furnace is signaled to come on, this sequence of sounds should happen.

2a. You will hear a "click" and then the furnace blower should run. It is purging the combustion chamber to make sure all is clear inside the furnace.

2b. After a time period, approx 30 seconds to a minute of the blower running the burner should lite and a large "whoosh/roaring" sounds starts and it will stay sounding like this while the burner is running.

3. Heat will come out of the vents after a small amount of time.

4. The burner after it has been running a period of time, may cycle off with the blower still running and then the burner turn back on. This is the high temp switch inside the furnace shutting the burner on and off.

5. Once the room temp reaches the furnace setpoint on the T stat, the burner will shut off and the blower keep running.

6. After a time period, the blower will stop after the heat chamber has cooled down.

7. The furnace will wait until the room temp falls below the T stat setting and then start back over.

It might be you cannot get past no. 2. Don't know, you tell us. If the blower does not start to run when the T stat calls for heat, that is problem 1 and we have to get past that.

How friendly are you with 12 volt DC electricity? Do you have a volt meter and know how to use it?

Hope this helps

Thanks

John

Andy Vidra · 09-18-2017, 01:24 PM

Here is something bordering on the truly weird. My camper is plugged in to and everything is properly functioning. I had the battery checked by a NAPA dealer while I was out camping and the battery was fully charged and properly operating under load. The reason I started checking fuses was that I was not getting any reaction when I turned the furnace on even though it has always operated properly in the past. On a hunch, I decided to open up the thermostat in an attempt to start tracing an electrical problem. With the cover off of the thermostat, I tried turning the furnace on. To my surprise the furnace clicked on exactly how it is supposed to.

I then turned the furnace of and replaced the cover. I tried it again and nothing happened. I took the cover off again and the furnace works. I got out my trusty xacto blade and cut the slot on the on/of switch deeper on the cover than it was. Put the cover back on and BINGO the furnace is working like it is supposed to.

There seems to be a little play in the on/off switch and this may be responsible for the cover not letting the lever go down enough to make internal contact. I have never run into something like that before.

Thanks for the time you took, John and Hutch. Without your input I would not have looked so far out of the box for the ultimate solution.

Andy

**JohnB** · 09-18-2017, 06:36 PM

Hi Andy,

You did a great job on troubleshooting this!!!

The first thing to check is you did not make it past item 2 above, the blower did not start, is to check the thermostat and make sure it is sending a signal to run. And you did this!!!

The cover must of been pushing the switch in such a way it did not make contact. Good fix and great it was that easy.... Now you learned some more about your furnace hoping to not have to use that info again.... but if it does, you know where to start.

Thanks for reporting back.

John

**Sunline Fan** · 09-19-2017, 10:59 PM

Wow, what an unusual but simple fix! Someone must have leaned on the thermostat, or put their hand on it when changing the temp, and pushed the cover in a little more than it had been. Still seems odd to cause total malfunction just from that small movement.

Andy Vidra · 09-20-2017, 08:30 AM

My tiny wife is the only one who operates the furnace controls. I think the problem lies in the switch itself. There should be three stop points with the switch. Up is A/C. Down is furnace. The middle id of. I now have four stop points with the middle two being off. The newly accessed fourth stop at the bottom is on. I had a friend over who was a heating/air conditioning engineer and he agrees that the switch has four stop points. He had never run into that before. I guess the lesson here is, if you have trouble with your urnace turning on, take the cover of and try it again. Painless first step.