Long story short, i hope.Suburban sf 35 f furnaceproblem just started a month back in middle of some cold weather.worked fine then one day just didn't start up again.turned thermostat up , nothing.turned thermostat of then waited a few hours. furnace turned back on for one cycle and never turned back on.repeated a few times to have it work, then wouldn't start at all.pulled unit out , cleaned it from mud dauber nest. all clear. hooked it up to external battery and propane and ran just fine.checked wires coming from thermostat, got 13.43 volts on one wire shore power and the other had none.coleman mach Thermostat turns on a/c and powers high / low fan. does not power fan when heat selected.so do u think this is a thermostat issue or a wiring issue where one wire may have a break?

I dunno, but mine is doing the same thing randomly (also a Suburban 35k BTU). It will always fire up when it's cold, but when the Tstat calls for heat again the fan won't run. If I shut it off and turn it back on a few times the fan will eventually run again. But it doesn't do it all the time. Sometimes it will work all day long no problem.I'm guessing it's my fan motor, but it's a guess. So...I'm subscribing to this thread :)Sorry I don't have the answer....

Mine quit completely. i took it out and worked great after a good cleaning and when i connected it to a battery and propane on he bench. so. i may just buy another thermostat and see if that will work. i don't think its the board because it works when i connect the 2 controller wires. the limit switch checks out with the meter and the sail switch must work since it did not cut off power to unit because it ran and ignited for a good long time. ill give another thermostat a try and if it doesn't do the trick then i'll return it.

If I follow correctly you can run the furnace while it's on the bench? Then when you put it back in the trailer it does not work correctly?Before you buy a thermostat you might try a test of removing the thermostat off the wall and connect the wire on the terminal labeled R (or RW) to the wire on the terminal labeled W. If your theory is correct the Furnace should run and heat. Let it run for a minute then disconnect the wires and it should shut off. Now let it cool for a few minutes and connect the wires again. If it works flawlessly then you most likely have a bad thermostat.

Mine stopped because the propane regulator on the tanks wasn't feeding it enough propane pressure. Worked fine on the bench, but not in trailer. The other propane appliances worked OK, but when the tech checked the pressure at range burners when the furnace was trying to start, the pressure was too low for the furnace. New regulator fixed it.

ill ck thermostat the way opnspaces suggested first. then go from there and ck regulator. my tanks are newly refilled and my stove works. so ill figure out a way to bypass regulator on trailer with propane line that has regulator that i used for bench test.

Furnace Troubleshooting | Good Sam Community

15 Replies

hhernandez13
Explorer
Jan 29, 2015
ill ck thermostat the way opnspaces suggested first. then go from there and ck regulator. my tanks are newly refilled and my stove works. so ill figure out a way to bypass regulator on trailer with propane line that has regulator that i used for bench test.
brulaz
Explorer
Jan 29, 2015
Mine stopped because the propane regulator on the tanks wasn't feeding it enough propane pressure. Worked fine on the bench, but not in trailer. The other propane appliances worked OK, but when the tech checked the pressure at range burners when the furnace was trying to start, the pressure was too low for the furnace. New regulator fixed it.
opnspaces
Navigator II
Jan 29, 2015
If I follow correctly you can run the furnace while it's on the bench? Then when you put it back in the trailer it does not work correctly?

Before you buy a thermostat you might try a test of removing the thermostat off the wall and connect the wire on the terminal labeled R (or RW) to the wire on the terminal labeled W. If your theory is correct the Furnace should run and heat. Let it run for a minute then disconnect the wires and it should shut off. Now let it cool for a few minutes and connect the wires again. If it works flawlessly then you most likely have a bad thermostat.
hhernandez13
Explorer
Jan 29, 2015
Mine quit completely. i took it out and worked great after a good cleaning and when i connected it to a battery and propane on he bench. so. i may just buy another thermostat and see if that will work. i don't think its the board because it works when i connect the 2 controller wires. the limit switch checks out with the meter and the sail switch must work since it did not cut off power to unit because it ran and ignited for a good long time. ill give another thermostat a try and if it doesn't do the trick then i'll return it.
turbojimmy
Explorer
Jan 29, 2015
I dunno, but mine is doing the same thing randomly (also a Suburban 35k BTU). It will always fire up when it's cold, but when the Tstat calls for heat again the fan won't run. If I shut it off and turn it back on a few times the fan will eventually run again. But it doesn't do it all the time. Sometimes it will work all day long no problem.

I'm guessing it's my fan motor, but it's a guess. So...I'm subscribing to this thread :)

Sorry I don't have the answer....

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Furnace Troubleshooting

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