Suburban furnace issue

[softballjunky]

Hi all, I tried searching for my particular issue but couldn't see a post exactly like mine. 12 year old suburban furnace in travel trailer that will turn on and blow hot for about 5 minutes and then shut off before getting to set temp. I cannot get it to turn back on for a while, then after about 30 minutes it will run for a few minutes then shut off again. Where should I start? Any ideas would be great. Thanks in advance.

[deltabravo]

Here's a good solution to keep wasps and fly insects out of the furnace intake and exhaust

[opnspaces]

When you say it shuts down after 5 minutes does the burner and fan shut down? Or does the burner shut down but the fan continues to run until you turn the thermostat off?

Are you plugged into shore power when this happens, or are you running off the battery alone?

Is there black soot on the outside of the trailer around or above the furnace exhaust port?

Can you find and tell us the model number of the furnace?

Do you have a digital multimeter to be able to take some readings?

Does your thermostat control only the furnace? Or does the thermostat control the furnace and the AC?

[CavemanCharlie]

softballjunky wrote:
For what it is worth, After it cycles off and I turn the unit on and off at the thermostat there is a clicking sound coming from the furnace. Not the kind of sound that happens over and over as it tries to ignite but just a single sound as I turn the switch on. Does that give you any further information? Thanks

I am not an expert. Just another RV owner like you. If the furnace was overheating then it has a overheat switch built in. After if shuts off on that the switch has to cool down before the furnace will restart. The clicking sound is the relay trying to turn the furnace on just like was stated above. But, it can't run because the overheat switch has not cooled down enough yet to automatically reset.

Again, I don't know for sure but, I still am guessing it's full of dirt from the wasps. That is why it is overheating. It can't "breath" good enough and exhaust the burnt gasses so it overheats and shuts off.

[rrupert]

It sounds like a relay that would supply the 12 volts to the fan and control board. The thermostat only powers the relay armature which in turn closes the contacts that connect the power to the furnace.

[softballjunky]

For what it is worth, After it cycles off and I turn the unit on and off at the thermostat there is a clicking sound coming from the furnace. Not the kind of sound that happens over and over as it tries to ignite but just a single sound as I turn the switch on. Does that give you any further information? Thanks

[rrupert]

softballjunky wrote:
Yes, it is the original that came with the trailer. I am sure there is no heat anticipator on it.

If it's an Attwood it probably has an anticipator. If you remove the cover you should be able to see a flat lever on the backplate. The ones I have owned the lever was moved all the way left which caused wide temperature swings. I moved the lever to about mid-point or 12 o'clock, and it evened out temperature swings. But I later replaced the old thermostat with an inexpensive Honeywell non-programmable digital thermostat. This made temperature management much easier.

[softballjunky]

Yes, it is the original that came with the trailer. I am sure there is no heat anticipator on it.

[CavemanCharlie]

poppa wrote:
im kinda new to tt's but am a resi ac guy. it mite be the heat anticipator on the thermostat. the other responses should be checked as well

Most TT thermostats are a simple mechanical unit. In fact many people replace them because they don't like them.

If he has replaced his thermostat you could be right.

[poppa]

im kinda new to tt's but am a resi ac guy. it mite be the heat anticipator on the thermostat. the other responses should be checked as well

[softballjunky]

Thanks for the information.

[CavemanCharlie]

Wasps love building nests in the intake and exhaust ducts of these furnaces. I once removed a furnace and dumped a whole coffee can full of wasps nests out of it. Try looking down your intake and despicably the exhaust duct for nests and clean them out if you see any. It might be enough. If not you may have to remove the furnace to clean it.

[opnspaces]

Probably heat related. BryantRV has service manuals online for download. Just scroll down to the furnace section
Link

[rrupert]

garyemunson wrote:
I'd suspect the high temp limit switch is failing and opening at too low a temperature.

2X that, or you may have an obstruction in a heat duct or a closed register.

[garyemunson]

I'd suspect the high temp limit switch is failing and opening at too low a temperature.