Atwood RV Furnace will not start after changing propane cyl

[64aggie]

I recently changed over to the reserve cylinder when I had the other 30 lb. propane cylinder refilled. Now my furnace, Atwood Hydro Flame 8531-IV-DCLP, will not start. When I turn it on, using the thermostat, nothing happens. The blower does not run as it normally did prior to the furnace lighting. I have tried switching cylinders. My Atwood Hot Water heater is working & I can use the Atwood propane range.

I have 12.4 volts through the off/on switch & the circuit breaker. The fan will run if I jumper this to the motor. There is also 12 volts from the thermostat and the ground wires all check out.

All web troubleshooting articles refer to a "relay" with four terminals. My unit does not have this, only the circuit board. Where is this relay? Also I get no light or flashes of the circuit board LED.

Any and all help is greatly appreciated. Thanks!

[eHoefler]

Check and make sure the propane cylinder has propane first. Then see if you can get the stove to light. If not, close the propane valve, remove the hose. Re-install the hose, slowly open the valve. Opening the valve to quickly can trip the OPD, ( Overflow Protection Device ) causing no flow of gas. Go back and light the stove, this may take a bit of time to bleed any air from the lines. Use a match or one of those butane lighters instead of the ignitor on the stove. When you get a solid steady flame, try the furnace. It should light, it may take a couple of tries to bleed any air.

[Golden_HVAC]

My guess is that the furnace stopped working, and then you tried changing the cylinders, and then found it is still not working.

So why did it break? If the fan is not coming on, the two logical things to check are +12 to the furnace. The second is the thermostat letting +12 volts go to the furnace to tell it to start? A blown fuse in either location can prevent this.

If you know about wiring, then pull off the thermostat, and short the red and white wires. If the furnace starts, the the thermostat is probably the problem. If it does not start, then it can still be a blown fuse to anything, or another problem.

You said the fan works while +12 is applied to it, so I am going to say it is most likely that the thermostat is the problem. Connecting the red and white wires might start the furnace, and prove the thermostat is not working.

Fred.

[1492]

Moved from Forum Technical Support

[jeffymac]

Did you turn the thermostat off and then back on? Not just sliding the temp adjustment down....but switching it off and then back on. Typically they will try to ignite 3 times and then shut down. Have to turn off and on to reset. Propane would have nothing to do with the furnace not even coming on again.

[Old-Biscuit]

The 'timed delay relay' is part of your ignition control board.

Some models it is a stand alone relay......power from ON/OFF switch/CB went to the relay and then to blower motor AFTER power come from T-stat that energized a coil which when heated made up path in relay for power to blower motor.

You have power to board and power from T-stat....blower runs when you jumper power.

Bad ignition control board OR bad connections/ground on board.

Replacement board......Dinosaur Board LINK

Atwood 8500 Series Manual (Limited but has wiring & part numbers) LINK

Atwood 79/80, 85 & 89 Series Manual....more info with troubleshooting LINK