Suburban 35FQ troubles

[Parked Home]

Hello everyone!
I'm having trouble with my Furnace getting it going most the time, and keeping it going after its heated if it does get started..

I purchased a 2016 Palomino Puma destination trailer about 2 years ago and it's been fantastic till just this winter it's starting to give me some issues,

It just recently has started getting cold where I am, and I've been trying to get the Furnace to kick on,

I hear the click for it to turn on but the blower motor doesn't always engage,
On occasion I can turn the Furnace off and on by the thermostat and get it to turn on and it'll heat up to temp but it doesn't always re-engage after it's heated, and some times I can't even get it started by turning off and on a bunch of times,

On my thermostat it'll show the correct house temperature, but just won't engage the majority of the time..
I'm honestly at a loss,
I do have propane to my stove so I know that's good, My thermostat will engage AC just fine, I even replaced my thermostat just incase and same thing is occurring,

I'm on 50 AMP shore power, battery is showing full.
thermostat has 12V,
I've replaced my Circuit board, So I know that's not the issue.
Ignitor has also been recently replaced the gentleman from the RV shop said that could of been an issue so I tossed one in.
Sail switch was also thrown in cause it was cheap and I had the furnace out.


let me know if any other information will be helpful, thanks for taking the time to read this, and any suggestions.

[fonzie]

On my unit, the motor had one brush that was not making good contact with the commutator. If you turn thermostat on and hear click and motor blower does not start, try to hit furnace encloser with your hand to see if furnace start. If it does then either you have loose connection or motor brush is not making good contact. I had to remove furnace, dismantle motor and make repairs. All good after.

Top brush not making proper contact with commutator.

[Parked Home]

gave her a good few wacks,she didn't kick on, turned her off turned the motor just to be sure it wasn't in a dead spot or something, and it didn't kick on.

I may of forgot to mention I did replace the blower motor as well. was one of the first things I did.

[loyda]

Sounds like you have basically rebuilt the furnace. Take furnace out and hook up to 20lb tank.

[Parked Home]

I have basically re built the entire furnace, aside from I believe the limit switch would be like the remaining part that I've yet to swap. I believe,

I can not remove my furnace, have it plugged up to power and the propane at the same time, the cables are so short it has to be in the cubby to reach the cables for power,
The stove top does fire up though with no issue, and I can turn it allll the way down and it won't turn off so I know the propanes getting there at least.

I'm in for a chilllllly week of 20-30 degree nights if I can't get this sucker fixed, may have to call a random repair guy if we can't figure this out which I was trying to avoid as I've already spent nearly the cost of a new furnace (saved about 30% rebuilding myself to no avail)

[Parked Home]

Okay, got home and after somehow coming across some new info....

my RV has a control box on the ceiling which is the noise I've been hearing "click" so my guess is, that it was getting passed the thermostat, getting to this control box..
well today I got home it was freezing of course so I went to kick on heat, no avail.. I move some cables on the furnace no avail, I pop open the cover near the ac unit, move a few cables and it INNSTANTLY kicked on. so this is where my issue lies... I must of been looking incorrectly in the Suburban trouble shooting manual because I thought it said it went thermostat -> circuit board on furnace was the order of operations,
but it seems it's Thermostat -> control box relay? -> circuit board.

I'm an extreme novice that's been trying to learn off of youtube videos these past few weeks and I've learned how to work on these things, but trouble shooting has never been my fort... even with a order of operations sheet apparently haha! I'm glad it's working, and hope it re-engages when it comes time to re-heat.
I'm assuming when I took out the cover to clean it that a connection was made loose, or smooshed, is this a common issue for Suburban's?

Thank you all for the help up to this point.

[Bama Rambler]

Sorry I'm late to this.

This isn't a furnace issue at all.
The way Dometic digital communication thermostats handle the furnace is to run the furnace wires through a relay in the A/C control box. So in essence the relay acts as the thermostat referenced in the Suburban manuals. Instead of Thermostat > Circuit Board, it's Relay > Circuit Board as you surmised.

Since you've esentially found the issue it will hopefully be an easy fix. Hopefully it's just a loose wire.

[Scrapper]

Since you stated you wiggled a few wires at the AC and it instantly kicked on you have loose wire connections in that set of wires. Sometimes just redoing or tightening the connections will fix the problem. If there are wire nuts or slip-on terminals involved you may have a problem with oxidation. You would benefit by a terminal paste on the wires and terminals. A inexpensive tube of silicon grease will work.

[Parked Home]

I will definitely be re-doing connections if the call to re-heat doesn't work, my comment prior I Just removed because I guess I ran out of propane after it got to temp so was a false alarm, I swapped to the other tank, and am going to see what happens after it heats up to temp.
I know which cable was the culprit if it doesn't work, it was the red one that was all wedged in a corner and when I moved it from being wedged it kicked on instantly, and has since still been instantly kicking on now when I either lower temp to cold and than raise temp back to hot, or just turning it off and on, both work everytime now, just hoping I wake up nice and toasty, we shall see. thanks for the help everyone..

I did order this https://www.amazon.com/gp/product/B01IU4712W/ and it came with a control box, if that is the issue,

thanks for the helps everyone, hope y'all have a great day I'll touch base with y'all tonight with the deets!

[Parked Home]

Alright, we're back in action!

Thank you all for your help, I've learned a ton on this project and am extremely glad to have the heat back working.
Apparently since my issue wasn't the parts I'll save all my now "spare" parts, and will have them for the future. I'm sure somewhere down the line I'll have to do repairs on it, and it'll be nice to have the parts already on hand, and have the understanding/confidence now to work on the furnace.

have a great rest of your week everyone, take care!

[Bama Rambler]

Thanks for coming back and letting us know that you got it working.

Was it a bad connection?
If so, where was it?

[Parked Home]

Originally Posted by Bama Rambler

Thanks for coming back and letting us know that you got it working.

Was it a bad connection?
If so, where was it?

heh, it was just a wire that was in the ceilin', same one that was like smooshed into the corner(the red one for me) I think while changing my filter this summer with the heat I tossed it back up and it smooshed a cable, it was summer so I didn't notice and I assume it was just getting enough of a connection to start on occasion maybe from it trying to start it, it'd move it or something sporadic like that, now that it's freed up it's perfectly running every time. and has been all night.

the biggest take away is that the thermostat is really controlled by that pesky box in the ceiling which was an extreme overlook on my part, whilst searching I was searching for "furnace clicking and not starting" which gives you an entirely different breakdown, instead of like "thermostat or control box clicking and not engaging"