Suburban SF 42 furnace help

[MooseSuite]

Thanks Hitch.

The limit switch is at the rear of the furnace, furthest from the exhaust pipe. $10 part. Didn't realize you could remove the back furnace cover plate to access replacing.

Amazing how one service call ant two parts equals the price a new furnace.

I guess it's like that with most electronics, ie microwaves etc.

 

[rvndave]

You can't access the stat wires from outside. From inside there should be four wires that connect to the furnace. Two of these wires will be the 12 volt power supply the other two will be the control wires that connect to the thermostat. I would disconnect the control wires at the thermostat if the furnace turns off after the cool down cycle I would replace the thermostat. If the furnace continues to run I would disconnect the control wires at the furnace. If this turns the furnace off I would look for a short in the control wires. If the furnace continues to heat after the control wares are disconnected I would check the control wires for a short inside the furnace. If no short is found replace the furnace control board.

 

[rvndave]

Altho I haven't used one myself, the Dinosaur boards are reported to be solid replacements--I am not aware of anyone who has gotten a bad one.
And congrats on figuring out how to remove it--not an easy task.
Joe

I installed the dinosaur board on my in laws rig it failed after a few years.

 

[stanleyz]

So, Gbill, did the board solve your problem. I have the same issue with a 42 but its complicated by my heat pump on the roof air which also has the same issue. It is intermittent but I'm sure I'll have to repair it eventually. Just wondered how you came out.