Atwood furnace

[jmcnulty89]

Hey guys I’m new to this form I hope I posting in the correct spot. so my trailer has an Atwood 8531-IV-DCLP furnace that is not working correctly.
When I turn the heat on nothing happens so I open up the unit on the outside it’s getting power all the way to the little round looking relay on top of blower but only the top post is getting power.so I took the blue wires off and jumped power to there after 15-20 seconds blower turns on and will run but that’s will not ignite. So still no heat I don’t know where to go from there
It has a dual function thermostat heat and ac

[enblethen]

Relays are pretty generic for Hydro Flame and Atwood furnaces as you can see in manual.
May not be all the problems but good bet!

[jmcnulty89]

Yea the only way to get tha fan to come on is jump out the relay when i jump out the relay is there anyway to make the furnace ignite

[enblethen]

Power should come into the relay from the battery through a circuit breaker on fan housing then go to one side of the relay, the opposite of the relay goes to the fan motor.
Verify power on red wire from battery. Jumper the contacts on relay red wires. Fan should start Power and fan runs by jumpering means the relay is bad.

[jmcnulty89]

I am sorry I did twist the two blue wires together and nothing happened. the relay I am referring to is the time delay relay it has constant power to top post bottom is to the motor and right side is ground left side is from the thermostat (these are the wires I cut and twisted together) the only way I can get motor to turn on is I jump out the bottom of the relay

[enblethen]

You must connect the two blue wires together!
The only round item that I think of is the hi-limit cut out, It is around 3/4 inches in diameter. It is item 32 in parts diagram that I have. It should have continuity.
Look at page 10, limit switch.
Manual

[jmcnulty89]

So the thermostat is duo-therm by dometic. And when I cut the the two blue wires nothing happens not even the fan.
The only Way the fan will come on is if jump power to the red wire at the bottom of the relay (I don’t know if it is a relay can’t find it on any parts diagram) it appears to be some sort of relay little round thing mounted next to breaker on fan cover[img][/img]
And as I said earlier I am new and I can’t figure out how to post pictures from an iPhone
Thanks for all the help it is greatly appricated

[enblethen]

There should be a blue wire coming off the small relay mounted to the fan housing. It should go to the sail switch, then a white wire to a hi-level limit switch, then to the circuit board.

[enblethen]

Not right away. The fan should run for 10-15 seconds to clear any gas, then the burner should light.

[jmcnulty89]

Should the burner ignite when I connect the blue wires

[enblethen]

Tie the two blue wires together. This should start the furnace fan, in 10-15 seconds the burner should come on. If this happens let it run for a few minutes. Now separate the two wires, the furnace burner should stop, furnace go into cool down mode then shut off.
If this all happens, you have a bad thermostat or the thermostat switch is in the wrong position.
Post make and model of thermostat.
If the fan starts but the burner does not start, the sil switch is not making contact. Could be a speck of dust. Use compressed air to blow out sail switch. Located in the back upper area of air fan housing.