Jayco service dept unable to fix furnace short cycling

[Doctor Chuck]

The service center we use has a secondary location near us at 7000 ft. I talked w/ the salesman here. He said he has sold lots of identical trailers to ours that are used up here at 7-9000 ft and no one has reported problems. So w/ that knowledge, what would you do?

[Grumpy]

Originally Posted by Doctor Chuck

The service center we use has a secondary location near us at 7000 ft. I talked w/ the salesman here. He said he has sold lots of identical trailers to ours that are used up here at 7-9000 ft and no one has reported problems. So w/ that knowledge, what would you do?

Have that service center check it. I think the issues are "hit and miss", as I mentioned earlier other JOF members have reported problems and it is not unusual based on what you find on the web. It even affects residential units.

The only other thing to do would be contact Atwood direct. They used to make a "high altitude kit" if I remember correctly.

[Gary207]

On my unit my heater is under the Jack knife sofa on mine there is no return air grill looks like the design was to bring the return air into the unit behind the sofa, just to eliminate your problem lift up the sofa prop it open see if that helps. We plugged up that gap behind the sofa with blanket’s to keep the cat from going under the sofa.

[Gary207]

One other thing on my unit I found the propane line/hose leading to the furnace under the trailer bent at a manifold this could restrict the flow of propane to the unit, the manifold is behind the rear wheel.

[Doctor Chuck]

Originally Posted by Grumpy

Have that service center check it. I think the issues are "hit and miss", as I mentioned earlier other JOF members have reported problems and it is not unusual based on what you find on the web. It even affects residential units.

The only other thing to do would be contact Atwood direct. They used to make a "high altitude kit" if I remember correctly.

The service center told me they contacted "Dometic" and no high altitude kit is avail for my furnace.

[Doctor Chuck]

Originally Posted by Gary207

On my unit my heater is under the Jack knife sofa on mine there is no return air grill looks like the design was to bring the return air into the unit behind the sofa, just to eliminate your problem lift up the sofa prop it open see if that helps. We plugged up that gap behind the sofa with blanket’s to keep the cat from going under the sofa.

Appreciate the thought. Tried propping it up and didn't help.

[us71na]

Originally Posted by Gary207

On my unit my heater is under the Jack knife sofa on mine there is no return air grill looks like the design was to bring the return air into the unit behind the sofa, just to eliminate your problem lift up the sofa prop it open see if that helps. We plugged up that gap behind the sofa with blanket’s to keep the cat from going under the sofa.

How large is the opening into the box that contains your heating unit? The OP has indicated to me in a PM that his opening is 5" x 5" which seems very small for a cold air return.

[Gary207]

On that propane manifold a line from the propane tank goes into the manifold then one rubber hose goes to the stove one to the refrigerator and one to the furnace. A bent hose would close down the flow of propane to the furnace. What would happen there would be enough propane to start the heater and then not enough propane can get through the bent hose and the gas valve shuts off the hose fills up after the bend and starts again. On my trailer it looked the hose was to short and the heater installer pulled the hose and bent the hose.

[JohnWedell]

As another avenue to try check the voltage at the blower motor with it running in the trailer a low voltage condition may cause the blower motor to slow down and that might Cause the problem

[Doctor Chuck]

Originally Posted by us71na

How large is the opening into the box that contains your heating unit? The OP has indicated to me in a PM that his opening is 5" x 5" which seems very small for a cold air return.

I will measure today

[Doctor Chuck]

Originally Posted by Gary207

On that propane manifold a line from the propane tank goes into the manifold then one rubber hose goes to the stove one to the refrigerator and one to the furnace. A bent hose would close down the flow of propane to the furnace. What would happen there would be enough propane to start the heater and then not enough propane can get through the bent hose and the gas valve shuts off the hose fills up after the bend and starts again. On my trailer it looked the hose was to short and the heater installer pulled the hose and bent the hose.

I'll have to drop my underbelly to check that. Good thought though. My propane hose to my tank regulator is so short it's hard to change tanks.

[Doctor Chuck]

Originally Posted by JohnWedell

As another avenue to try check the voltage at the blower motor with it running in the trailer a low voltage condition may cause the blower motor to slow down and that might Cause the problem

Wil do though the blower sounds strong while running.

[Gary207]

The propane manifold is out in the open in plane site on my 2022 trailer. They did foam around the hoses going into the under belly.

[Doctor Chuck]

Originally Posted by Gary207

The propane manifold is out in the open in plane site on my 2022 trailer. They did foam around the hoses going into the under belly.

Thanks. I'll get underneath and check it out.

[tazdad]

Had a similar problem....dealer had unit for 6 months.....after replacing everything on unit...still short cycling....took unit out after 2 years to local repair.....put on bench....3 days later. Called said fixed....bad igniter...... 30 dollar part....took 2 years to fix.....has worked perfectly ever since....

[wondermn1]

We have a 2016 Jayco Precept 31 UL and it took 2 years for them to completely change out our furnace. They replaced mother boards 3 times, new cases and covers and 5 stops at the service center in MANTECA CA. We live Hawaii so each service cost us round trip air and hotel stays. I love the Precept but hated the warranty service. works fine now

[jmjaklein]

Our Pinnacle had the same issue. The local RV repair guy knew exactly what to do. Repaced the control board. He said he had replaced the control board in most of the Jayco units in the Park. The original boards are from Korea.Worked fine since he made the switch for us.

[MPD56]

Originally Posted by tazdad

Had a similar problem....dealer had unit for 6 months.....after replacing everything on unit...still short cycling....took unit out after 2 years to local repair.....put on bench....3 days later. Called said fixed....bad igniter...... 30 dollar part....took 2 years to fix.....has worked perfectly ever since....

Interesting but believable?

Top of my head

Higher altitude means thinner air , less oxygen so the flame would be yellow.
Incomplete combustion.

The flame should be blue and with proper pressure, the blue should almost touch the burner. The higher the pressure, the more the flame moves away from the burner ( flame speed).


The next person you ask to look at it, ask if he has a G1 license. Most RV techs don't. There is a few things I can think of that will do this and it should take less then an hour to diagnose.

I'm licensed to work on furnaces that are over 400,000 btu.

If it was me
1-A quick look at the flame
2- something is turning off and on. To me it most likely is a control component.

I don't like telling people to play with gas over the internet. But if you put something over the the rads, covering them, the cycling should change.

When you find out, please post, it's what makes this forum great

[Lmdye]

We have a 2018 24RBS, our domestic furnace stopped working after a month. Talked to a Jayco Dealer in Anderson CA, who was seeing a lot of these furnaces failing, the same way you are describing. They were told by Dometic to replace the control board, once we did that the furnace has worked fine, with no issues.

[myflyertrains]

So my 2015 Jayco had the same problems. My dealer was incompetent and never could / would fix it. Mine works most of the time now. Here is what I found. The 12 volt wiring is fed with very small wire, maybe 14 gauge... I ran new wires that were like 10 gauge to inverter connections under the bed. The voltage on the PC board was dropping to less then 10 volts when the blower motor was running. If the house battery was charging things worked pretty good, but when dry camping it was a no go. The burner kept going on and off. It would maybe run 5 or 10 seconds. The other thing to look at is the vane switch that senses air flow. mine was rubbing and did not move freely. Good luck with this it took me years to get mine working...