Furnace Driving Us Crazy

[TE1956]

Thermostat: Coleman-Mach Digital 9420*381
Furnance: Furrion FFG35FA or FFG35RA

Brought the unit home April 4 and temperature was in the lower 40s. Turned on the heat and everything was looking normal. Next morning was 29 degrees outside and 46 degrees inside. Thermostat was set to 65 degrees. According to thermostat a heat call was being issued to the furnace. Turned tstat off then on. No help. Checked fuse (good), unit was on shore power, batteries were showing 13.6V. Pulled the exterior cover to furnace and did a visual inspection. Found the fan had ingested the arm from the sail switch. Towed the unit back to the dealer which is 100 miles away. Dealer kept it overnight during which the sail switch was replaced and the furnace was run for a couple of hours.

Brought the camper home, hooked up to shore power, set the tstat to 65 degrees. Gets up to 58 degrees and the furnace starts vibrating, then quits. Sail switch arm was gone again. Technician came and removed the furnace and had it overnight. He found the fan had a missing blade, so the fan was replaced. When he came back the next day, he brought a new furnace which did not run. Put the original back and it fired up. The system seemed to be working fine. It would come up to the set point, I could vary the set point and the furnace would turn off and back on as it should.

i slept in the camper last night and the heat was cycling properly and temperature in the camper was holding around the 70 degree mark. I woke up around 2 AM and the temperature was at 62 degrees. Outside it was 38 degrees. Recycled tstat, no help. Pulled the furnace fuse, reinstalled, turned tstat back on and heat came on. About 5 minutes after furnace came back on, I noticed there was a vibration. The unit ran until it hit the set point and shutoff. Once the interior temperature dropped enough, the furnace came on for about 3 seconds, then shutdown. Pulled the fuse, turned the tstat back on and it ran through the cycle but with the vibration starting about 5 minutes into the cycle. This process continued through the night.

Any suggestions? I think I should have a new furnace as a minimum, but why is it locking out the way it is?

[Country Campers]

I think there is a bad batch of furnaces in the mix, seems to be a few keep showing up once and a while with issues recently. Maybe a call to GD Customer Service with these issues is warranted. And I agree I think a new furnace should be in order.

Brian

[Scott'n'Wendy]

I would agree a new furnace or at least a new motor/fan assembly. My guess, seeing as it is a new fan is the motor bearings are pooched.

[Nickmccartney]

I’ve had a VERY similar problem minus the vibration. Still no solution

[howson]

Nickmccartney and TE1956

The good news (it's a stretch but...) is the Furrion can be replaced with a Suburban. At least that's what Furrion's documentation suggests. See https://lci-support-doc.s3.amazonaws...cd-0008535.pdf

[TE1956]

Thanks for the feedback. It is going back to the dealer again. Hopefully something is resolved this time.

[Hiker52]

We have a 2024 Solitude 370DV, took delivery April 13, unfortunately I didn't have the dealer turn the furnace on when we did the walk through. Turned it on yesterday and I thought it was going to shake the trailer apart. Shut it off but it continued to run, shaking was terrible. I video recorded some of it and sent to the dealer. They just want me to bring it in and leave it. 90 miles one way so I would need 2 trips. The pre delivery report signed by the dealer indicates the furnace worked and they did a burn off. I don't think it had been ran. Planning to call GD tomorrow. BTW I noticed that it was not screwed down on one side. Only 1 small screw holding it down. Very poor quality control from GD.

[howson]

We have a 2024 Solitude 370DV, took delivery April 13, unfortunately I didn't have the dealer turn the furnace on when we did the walk through. Turned it on yesterday and I thought it was going to shake the trailer apart. Shut it off but it continued to run, shaking was terrible. I video recorded some of it and sent to the dealer. They just want me to bring it in and leave it. 90 miles one way so I would need 2 trips. The pre delivery report signed by the dealer indicates the furnace worked and they did a burn off. I don't think it had been ran. Planning to call GD tomorrow. BTW I noticed that it was not screwed down on one side. Only 1 small screw holding it down. Very poor quality control from GD.

Keep in mind that an insect may have built a nest in the furnace between the time it left the factory and when you turned it on. In other words, leave room for consideration that it may not be a GD installation (or operational check) issue.

I'd want to know WHEN the dealer ran the furnace "burn in". If it's been awhile, the nest could also have been built after they did their test.

The owner's manual for the furnace will declare in foreboding terms that a screen should not be used, but many have used them (me too) with success. Of course they must be kept clean.

[TE1956]

This is not the problem. The dealer swapped furnaces and even bypassed the heat pump by wiring the furnace to the thermostat. The system will still bring the interior up to the set point, shut off, and when the temperature drops below the set point by two degrees, the fan spins up then shuts down. This is repeatable on a very consistent basis. The only way to work around this is to pull the furnace fuse and reseat it, or go into the front bay and turn recycle the battery disconnect. My position at this point is there is a Grand Design issue with this model! We took possession of this unit on April 4, 2024 and haven’t even been able to sleep one night in it. And, it is still sitting at the dealer with no resolution. We rescheduled our shakedown to Fort Collins, then canceled that trip. We have a trip planned to the Pacific Northwest starting May 16 and it is not looking good at this point. Sorry to vent, but not sure Grand Design is in our future going forward! I’m sure it isn’t bees in the bonnet at this point!

[howson]

TE1956 -- post 8 was directed at Hiker52 who has a vibration issue (I know that part of your issue is resolved). Sorry -- I should have moved the other individual's problem to a separate thread as obviously you mistook my reply in post 9 for an input to your temperature issue.

Have you contacted GD Customer Service and asked for their assistance?

If you're not aware, there could be three components to the system in question. There's the furnace, the thermostat, and then the air conditioner plenum. That last component is the part of the air conditioner you see in the ceiling from inside the camper. The thermostat's wiring may go to the plenum first and then to the furnace. Inside the plenum is a control box with relays and, in some case, a remote temperature sensor. See https://gdrvowners.com/forum/operati...ssue-yes-again for how a system with a Furrion thermostat and Air Conditioner was configured.

What I don't know is how a Coleman thermostat interfaces with a Furrion furnace. What brand of air conditioner is installed in your unit?

Wish I had something more definitive to pass along and I certainly understand your frustration. It's a relatively simple system with limited components. The only difficulty should be if there's an internal wiring fault (meaning the discrete wires in the walls and/or ceiling running from thermostat to plenum and then plenum to the furnace).

Howard

[Scott'n'Wendy]

Well if two different furnaces behaved the same way...The problem would be with the commands to the furnace I'm thinking. Did they try a different tstat?
Is it possible there is an incompatible tstat being used?
It shuts off initially at set point so I'd bet it is not the over temp shutting it down causing it to fault and need a reset....hmmm
Pulling power all the time is just rebooting the furnace board. So you would think it was the furnace board. But with two furnaces behaving the same way, it's almost a garantee the furnace is not the problem. It seems the tstat can initiate turning on the furnace, but then maybe when temp is reached it is not turning off the furnace in a way the furnace expects...causing it to fault and shut down. Then needing a power cycle rest to operate again.
This could be caused by incorrect wiring or incompatible tstat, or incorrectly configured tstat.

[TE1956]

howson my apologies on not paying closer attention to that post. I am trainable, so will add this to my lessons learned folder. I have contacted GD customer service and my dealer has contacted tech service for a mobile tech (SRT?) to come look at it. I know the wiring from the t stat goes to the ac/heat pump then to the furnace. I’m unsure what brand/model the ac/heat pump is since my manuals are in the camper at the dealer.

@Scott’n’Wendy to my knowledge the tstat has been swapped, furnace has been switched with one of same model, and the tstat was wired directly to the furnace with the same result. As near as I can tell, the furnace has two wires for power/return, and two blue wires associated with the sail switch and limit switch.

Does anyone know if wiring schematics are available for these campers? It would be helpful to see how everything is tied together.

Once again, thanks for the feedback.

[Scott'n'Wendy]

Does anyone know if wiring schematics are available for these campers? It would be helpful to see how everything is tied together.

Once again, thanks for the feedback.

They are not available

Diagram for individual devices would be in your owner manuals, or available for DL from the manufacturer.

[howson]

Once again, thanks for the feedback.

You're welcome.

Post a picture of the a/c plenum (what you can in the ceiling) and we'll have a good idea of what's in your unit. Add a picture of the compressor/fan assembly (the part of the a/c that mounts on the roof) and we'll have a very good idea of what's installed in your unit.

Howard

P.S. Scott is, unfortunately, correct that there's no wiring diagrams for our trailers. Easily the #1 most FAQ on this forum. Check out the Welcome Letter to know more about this place and how to get the most from your time here.