Community Forums

oemail9813 · 12-17-2020, 08:53 PM

Furnace worked perfectly for 10 days, filled propane tank and went to use Suburban Furnace. Dometic Thermostat is set to 70 degrees with outside temps at 27 degrees. Suburban furnace blower kicks on, hear ignitor lite, air warms and then system kicks of in 5 - 10 min and never kicks back on. If I turn the thermostat off for a moment, turn it back to Furnace, the entire process repeats itself.

I have hot water and the propane stove top works fine and I looked to ensure none of the vents were being blocked inside the coach. Any thoughts on where to start for troubleshooting? Thermostat or possible the high limit switch? Are these easy to bypass to test or do I start somewhere else?

Thank you in advance for your help.

2004 Western Alpine 40'
Suburban Furnace

NITEHAWK · 12-17-2020, 09:00 PM

New Universal thermostat at your RV dealer--around $26
My furnaces(s) did the same thing, but about five years apart.
Purge blower. Ignite for about 10 seconds. Purge blower. Then Off.

Old-Biscuit · 12-17-2020, 09:13 PM

When furnace kicks off......does fan still run 'cool down' cycle
OR
Does Fan shut down also????

Could be 'timed delay relay' failing
Could be thermostat issue

oemail9813 · 12-21-2020, 02:42 PM

The fan goes off.

Old-Biscuit · 12-21-2020, 03:20 PM

Quote:

Originally Posted by oemail9813

The fan goes off.

Thermostat is just a 'switch'

Furnace functions are controlled by furnace components/circuit board

Fan shuts odd ....no cool down cycle
That is the "timed delay relay' failure

oemail9813 · 12-23-2020, 07:49 PM

Quote:

Originally Posted by Old-Biscuit

Thermostat is just a 'switch'

Furnace functions are controlled by furnace components/circuit board

Fan shuts odd ....no cool down cycle
That is the "timed delay relay' failure

Old Biscuit, I was wrong. The fan does stay on. I felt the air cool and thusly it was clearing out the line after the gas was shut off- I felt the air cool.

I took the thermostat (Dometic CCC 2) off the wall in hopes to bypass it and test to see if it was the culprit. Hoping to use a lead test, I found a Communicaiton wire into the back of the unit and not the expected wiring. I just purchased this unit and I’ll be damned if I know where this communication wire runs to. I am assuming the one of the dometic units. Can I assume the furnace wiring will be there too? Any thoughts?

Old-Biscuit · 12-23-2020, 09:25 PM

Quote:

Originally Posted by oemail9813

Old Biscuit, I was wrong. The fan does stay on. I felt the air cool and thusly it was clearing out the line after the gas was shut off- I felt the air cool.

I took the thermostat (Dometic CCC 2) off the wall in hopes to bypass it and test to see if it was the culprit. Hoping to use a lead test, I found a Communicaton wire into the back of the unit and not the expected wiring. I just purchased this unit and I’ll be damned if I know where this communication wire runs to. I am assuming the one of the dometic units. Can I assume the furnace wiring will be there too? Any thoughts?

Communications harness goes to control module in ceiling where the AC Unit controls/wiring is (Return Air Filter/Evap Coil area)

https://www.forestriverinc.com/broch...eticManual.pdf

raeburn2000 · 12-24-2020, 07:52 AM

Obvious answer, but if you recently bought propane, maybe the regulator is closed or excess flow valve tripped closed. Try closing the propane regulator and then opening it slowly. That should also fix the excess flow valve issue.

Old-Biscuit · 12-24-2020, 10:35 AM

Quote:

Originally Posted by raeburn2000

Obvious answer, but if you recently bought propane, maybe the regulator is closed or excess flow valve tripped closed. Try closing the propane regulator and then opening it slowly. That should also fix the excess flow valve issue.

OP stated:
Suburban furnace blower kicks on, hear ignitor lite, air warms and then system kicks of in 5 - 10 min and never kicks back on. If I turn the thermostat off for a moment, turn it back to Furnace, the entire process repeats itself.

Furnace wouldn't run for 5-10 minutes if Excess Flow Device was tripped or no propane flow

Problem is within the furnace -----component that allows DC to FAN

andy29847 · 12-25-2020, 07:43 AM

The modular cords run to the front AC. Access to the control board is from the top, but you can get in from the bottom to unplug the ends and check for corrosion.

I had a problem with the heat on my 2001. I traced it to a wire splice in the compartment with the heater (under the fridge on my unit). The wires had been twisted together, covered with vinyl tape and fastened to the floor (I think it was a factory job). Over the years, the wires had corroded, and I had a high resistance connection. Sometimes it worked, sometimes it didn't.