Furnace comes on with thermostat set to off

[Outsider]

I have searched the forums for 30 minutes without success so here is my question/problem. My Suburban gas furnace (in my newish to me 2015 Coachmen Clipper 16B) attempts to light in cold weather even with the thermostat set to OFF. The lowest thermostat setting is 50 and then OFF but the furnace will attempt to light when the temp drops below 50. The furnace works properly when I turn the gas on, there just doesn't seem to be a TRUE OFF.


Ideas? - Thanks.

[valleyduo]

What type or model of thermostat do you have?

[Bama Rambler]

As the Duo said, tell us the brand and model thermostat and we'll have better advice.

[Outsider]

Here's the short version of how it works apparently. I do not have any paperwork on the Suburban thermostat Mdl 1405T so I was unaware of this.



When I pulled the cover off to get the mdl # I found that sliding the temp adjustment lever on the top all the way to the left it stops solidly at what appears to be the OFF setting. With closer inspection I found that it was stopped by a small tab built into the back plate. If you pull the lever slightly forward and then to the left it will travel past that tab an additional 1/8 inch to the left and the little triangular pointer you see on the left side of the temp adjustment lever opens the copper/metal contact there and totally turns the system OFF. (Rotate pics 90 degrees right for proper viewing.)

[Bama Rambler]

Glad you figured it out and now know how it works.

Thanks for posting pics of it. It makes it clearer to see the mechanism.

[Trainman736]

I had the same problem. I didn't realize the lever was actually set at its lowest setting, but NOT "off". When I turned it "off", the fan was still running.

On a similar thread a few weeks ago, someone commented that they found a "RESET" button on their unit, outside. My Thor Class C24 had nothing outside but the propane vent, so I took the black cover off inside. There was a very large, unmarked button, front and center. I pushed the button, and the fan went off! Give it a try!

[glsimms]

Originally Posted by Trainman736

I had the same problem. I didn't realize the lever was actually set at its lowest setting, but NOT "off". When I turned it "off", the fan was still running.

On a similar thread a few weeks ago, someone commented that they found a "RESET" button on their unit, outside. My Thor Class C24 had nothing outside but the propane vent, so I took the black cover off inside. There was a very large, unmarked button, front and center. I pushed the button, and the fan went off! Give it a try!

Thanks for posting and

[MtBiker]

First change I made to my Coachman 15RB was to ditch the stock thermostat and buy a basic $15 digital one. Two screws, two wires, done.
You can set it at exactly the temperature you want it to be.

[rockfordroo]

Originally Posted by MtBiker

First change I made to my Coachman 15RB was to ditch the stock thermostat and buy a basic $15 digital one. Two screws, two wires, done.
You can set it at exactly the temperature you want it to be.

X2. Those analog things are JUNK.

[Lee Pedrick]

FYI,,,,when you turn the heater off, the fan is designed to keep running for a few seconds or longer to cool down the heat chamber to a safe level and then it shuts off. If it does keep running say for maybe 5 minutes, then I would replace that thermostat.

[Trainman736]

One of the messages on the forum said that the fan will come on if the house battery is dead. I turned on the "use" switch on the battery and plugged in the 120 shore power and things are fine now. I am not sure what I did, but I am not questioning it! Obviously, the "push the large button" advice was not correct. Sorry!

[rockfordroo]

Originally Posted by Trainman736

I had the same problem. I didn't realize the lever was actually set at its lowest setting, but NOT "off". When I turned it "off", the fan was still running.

On a similar thread a few weeks ago, someone commented that they found a "RESET" button on their unit, outside. My Thor Class C24 had nothing outside but the propane vent, so I took the black cover off inside. There was a very large, unmarked button, front and center. I pushed the button, and the fan went off! Give it a try!

Even with the thermostat "off," there is still power applied through the time delay relay to run the fan for a short time to cool the furnace down. See attached Suburban wiring diagram.



There is no reset button shown.

1) Do you have a Suburban furnace?

2) Can you post a pic of this button? Is it possible the button is on the time delay relay and you manually shut it off before it would normally have done it?