Atwood 8531 IV DCLP blower not running.

[hallm]

Hi Folks new member here.

I have an Atwood 8531-IV DCLP furnace and a couple of days ago it stopped working and of course it was cold! When I request heat my digital thermostat clicks in but now the blower sequence does not initiate and the furnace does not respond.

Here is what I have checked so far
- The digital thermostat has a fresh set of batteries in it and I have confirmed continuity of the relay in it when it engages and calls for heat.
- The 15 amp fuse for the furnace in the breaker panel is good.
- I have power going to the thermostat and down to the furnace when the thermostat requests heat.
- The switch on the motor is in the on position
- The 10 amp circuit breaker on the blower housing is depressed in the reset/on position.

I have been digging through posts on this forum trying to find other campers with a similar problem with the hope of finding a possible solution.

I came across this posting https://www.irv2.com/forums/f54/atwo...an-559948.html which is very similar to what I am experiencing.
The wiring diagram with the TDR is the same as my unit and I am wondering if I also have a failed relay.

Would I be correct in assuming that if I had power coming from the thermostat down to the TDR and if it has failed then I would not have any blower activity?
I was able to get my fingers into the blower fan and it does spin freely, but I have yet to test the motor by applying 12 volts directly to it to rule out a dead motor which I intend to do.
Would it be a fair assessment to say that if the sail switch and the upper limit switch were to be defective they would still allow the motor to start even though they are of the proving process after the blower starts?

If my TDR is bad then just changing that part of the system is going to cost me around $80.
If I purchase a new dinosaur board then it would replace my current board (if it might be part of the problem) plus it would contain the same function as the TDR on the new main board. Do I have this correct?

Is there anything else I am missing in getting my furnace back on line.
Thanks in advance
Mike

[Old-Biscuit]

IF yours had the TDR then to test just remove the DC+ wire from furnace on/off switch at TDR (RED) and connect to Fan Motor led from TDR (RED)
*That will bypass TDR

Fan runs........TDR bad


YES the Dinosaur Fan 50 Plus board incorporates TDR function onto the circuit board

[hallm]

Old-Biscuit - Thanks for looking at and commenting on my post.

I did as you suggested and sure enough the motor fired right up.
The replacement relay on Amazon ( I believe its from Dinosaur) is $90 where I am.

I see that Dinosaur offers several diffident versions of it control boards. Would you be able to suggest which of there boards would be suitable for unit.

Thanks again for your assistance.
Mike

[hallm]

Old-Biscuit

- I pulled the relay and cleaned up the contacts in hopes that it would correct the problem but no luck. I place a jumper across the two red terminals and had my wife set the thermostat for heat. The blower started up and several seconds later the burner ignited and ran as usual. You were spot on with your advice.

Relay is toast!

So now the hunt is on for a replacement relay or an upgraded control board which incorporates the blower control.

If anyone has replaced the control board in their Atwood 8531 with good results I would appreciate any reconditions for what they used.

Thanks in advance for your help.

Mike

[Old-Biscuit]

Dino Fan 50 Plus as mentioned earlier

https://pdxrvwholesale.com/products/...ard-fan50pp%20

[hallm]

Old-Biscuit

Thanks for the board recommendation. I have one on order and hopefully this will resolve my problem.

Thanks again for all you assistance it was very much appreciated.

Mike

[Old-Biscuit]

Post back up after you get new board in and furnace running

[hallm]

Yes I intend to let you know the final outcome. I am hoping the board arrives before I have to return to my home otherwise it’s going to be a couple of weeks before I return to the trailer.
It should make it since Amazon says it has already cleared customs in Toronto. Fingers crossed.

Thanks again for all your help.
Mike

[hallm]

Well wouldn't you know it! We had to head home today and just an hour after leaving the trailer Amazon shows up with my replacement control board. Its going to be 3 weeks before we are back at the trailer so I let you know how the the final install goes. At least when we go back it will be warmer and we won't be freezing.

Mike