Roadtrek Fridge No Cool on Gas - Dometic RM7401

[OldPilot]

I have a 2007 Roadtrek with a Dometic 7401L Fridge. I cannot get this thing to cool adequately on Propane Gas. It seems to work okay on AC, really have not judged it on DC. I just recently purchased the RV and at first had troulble igniting the gas function. The igniter would click, click and not go. I "tapped" the gas valve a bit and since then the gas ignites just fine and stays lit. The fire burns steady but apparently does not get hot enough. I can put my hand on the chimney - it feels warm - but it is not too hot to touch.

I've tried various movements on the thermostat dial, but that did not seem to have any effect.

On these Roadtreks the vent opening is really too small to allow easy access to the burner assembly. Has anyone had success getting in there? I got my compressor and blew some air, but it was only enough to keep the flame constantly lit, but not enough apparently to get the ammonia boiling. Well...what else can I try? I cannot really see how I can get the orifice and burner out to soak in alcohol. Has anyone else been able to do this?

I am currently letting the fridge cook all night long on gas just to see how good bad it is. But I'm hoping for some other solution.

[GallenH]

My Dometic is 10 years older than yours. Have you tried to get documentation? I found some Dometic publications in the internet. You might find something here: https://techsupport.pdxrvwholesale.c...ometic-rm7401/.

My Dometic does not have a circuit board. So it regulates temperature by putting the flame into "pilot" mode when the temperature inside the fridge is reached. I can see the flame go from high (when it's cooling the fridge) and low (when temp is reached). Yours is probably different. Circuit board models, I believe, turn the flame off completely and relight it when cooling is required.
If that's what yours does:

1. Check the gas flow to the unit. If the LP pressure is too low, it could result in a reduced flame. Dometic has specs for that. You probably need a RV tech to do this check.
2. If that's ok, I'd try to clean the jet in alcohol (as you indicated in your post). Careful: get the LP gas out of the line by turning it off at the tank while the fridge is working on gas and watch for the flame to go out.

You need docs on your unit.

Good luck

[mkguitar]

I have a different model dometic ( RM2500 series) , my manual was available to download free on the web


by doing a few small tweaks, cleaning the chimney stack, adjusting the igniter point gap etc I have very good result. starts up quicky and cools well (much faster than on AC)



no special tools or anything, just a few tweaks per the manual


when it's on, the heat coming out the stack is more than a hand can take

[OldPilot]

Well, I left the gas burner on all night. This morning the flame was still on but evidently too low. I could put my hand on the stack and it was barely warm.

I wish the vent opening was bigger so I could get in there to remove the burner and get it good and clean. Any idea on how to do that?

Thanks to @GallenH for the link to the installation/operation manual. I did not have that. Maybe I need some kind of diagnostic manual. I've had RV fridge before in a trailer and was able to easily pull out, inspect, and clean parts on the back. But this class-B is a different animal.

....still looking.....

[hbn7hj]

It ain’t that hard to pull the fridge. Do it if you have to. First check for 11” of water gas pressure.

[OldPilot]

Yep...good suggestion from @hbn7hj, I checked the pressure at the test point going into the fridge's gas valve. All okay @ 11". Fire burns solid but looks low fire. Barely 90 degrees at the lower part of the chimney. Certainly not enough fire to get the ammonia boiling.

There is a cover guarding the flame and burner. To remove the cover I need to get at a philips screwdriver in a position below the bottom the of the vent opening. Pretty much a blind operation even if I found a screwdriver short enough but with good enough grip to get it out. I have no idea if I would ever be able to get the screw back in the hole later. I'm certain that there must be crud inside the burner. I guess there would be someway to remove the burner assembly and turn it upside down to clean, if I got the cover out of the way.

We are going to take a short trip in a few days, so we will work with electric only. AC when plugged in, DC while driving. Hopefully, there won't much time with electricity that we will have a problem. That's why I like the gas part -- never have to worry.

[GallenH]

This is what Dometic service doc says:

"The LP gas pressure to the refrigerator should be 11 inches water column with half of all BTU’s of the RV turned on. With all other appliances turned off, the pressure to the refrigerator should not exceed 12 inches water column. To check the gas pressure when the refrigerator is operating, there is a pressure test housing located just prior to the orifice."

So make sure that you're getting 11iwc when other appliances are on. Here's what they say for bad LP performance:

"Insufficient cooling on gas.
Cools properly on other mode(s).

LP Gas Pressure
Thermostat
Filter
Orifice
Burner Flue
Baffle Flue Tube"

[hbn7hj]

It is not that hard to pull the fridge. You will have to do it eventually anyhow so get over it!

Let us know if you have any trouble. The main complication I’ve heard of is it can be stuck to the floor. Just work with it till it moves. I think there are two screws into the floor in the back.

Pull it into the aisle put it face down on the bed and clean the burner. You may as well burp it while it is out (store it upside down for a while.)

Note the insulation on top of it. Make certain it is in place when you put it back in. It is vital.

If you believe in an ARP unit (most do not) now is the time to put it in.

[reilym]

We just got back from our winter escape through Texas. Somewhere in Arkansas, propane stopped working on the fridge. Turns out that the LP regulator went out on day 3 of our trip. It became clear when the stove burner would go for a while and then die. After waiting a while, it would go and then die again. A new regulator in Little Rock solved the problem. Probably not your issue since you have a steady flame on the fridge, but worth checking. I carry a spare regulator now.

[engnrsrule]

I have a thread on my replacement of my Dometic 3-way. Had similar issues to what your describe.

Am very happy with results, maintained 3 way Dometic. Considered household but really wanted propane and 12v capability as we boondock a lot and did not have space (or desire) to expand solar to handle the load.

I also improved the ventilation both at the back and inside.

One caution, it is very important to ensure the combustion area is completely sealed from living space due to risk of carbon monoxide.

[ChicagoTom]

[QUOTE=OldPilot;144977] There is a cover guarding the flame and burner. To remove the cover I need to get at a philips screwdriver in a position below the bottom the of the vent opening.

You should be able to get it off. That screw is not in the best spot, but definitely made to be removed. I can't recall, but I think I just used one of these. If that doesn't work, there are several options for tight spaces available. https://www.amazon.com/I-MART-Offset...s%2C194&sr=8-2

[ChicagoTom]

Just saw this one and ordered one. Looks like it would make life easier....maybe https://www.amazon.com/gp/product/B0...0?ie=UTF8&th=1

[DWorrell3]

I had that arrangement. Frankly, it won't cool much below 40 degrees of outside temp on propane. Ergo, if it's 103 in Lubbock, TX, you won't bet much below 63 degrees on your fridge. I changed out to a/c. d/c Novacool and it works absolutely great. I can run it 2 days boondocking and a generator or engine start for 20 minutes will fully recharge the coach batteries. Dave W

[GallenH]

Originally Posted by DWorrell3

I had that arrangement. Frankly, it won't cool much below 40 degrees of outside temp on propane. Ergo, if it's 103 in Lubbock, TX, you won't bet much below 63 degrees on your fridge. I changed out to a/c. d/c Novacool and it works absolutely great. I can run it 2 days boondocking and a generator or engine start for 20 minutes will fully recharge the coach batteries. Dave W

Can you give some more specifics? What model Novacool and what is your battery AH capacity?

thx.

[DWorrell3]

I really don't know the amp hours... it's a typical battery setup for a 2012 RoadTrek 190 Popular, 2- 12 volt coach batteries. The product is a Noval Cool R4500 a/c, dc, $975. Would NEVER go back. Dave W

[GallenH]

Wow. That's an amazing price. In searching online they range from $1300 to $1600. Where did you buy it.

[DWorrell3]

Southern California Enterprises
1214 Rosecrans Street
San Diego, CA 92106
619-224-2869

Dave W

[GallenH]

thanks for the information

[OldPilot]

I stlil cannot get a full flame to burn hot enough to for the fridge to cool. I am sure the gas pressure going into the valve is adequate. I measured 11" at the test port right before the gas valve.

When I first got this van it would not ignite at all. After "tapping" on the gas valve a few times, I got the unit to consistently ignite whenever turned on. So now I wonder if this GV100 Solenoid Gas Valve is something that can be serviced? Is it possible that the valve is only partially opening so that the flame is less than what it should be?

Anyone ever opened it up? You can't buy these anymore.

[hbn7hj]

https://spares4dometic.co.uk/dometic...th-connections