Fridge cooling expectations on gas vs. AC

[ckerrick]

The Dometic refrig in our 2013 25' had similar little/no cooling problems when we first got the trailer. One of the issues was the thermistor, which is a plastic clip on a wire that connects to a cooling fin inside the refrigerator at the top. If the thermistor is not attached, the refrigerator will not cool properly no matter whether you're using gas or electricity. At first it was discovered that the thermistor wasn't attached. Later on after extended testing by LA Airstream it was discovered that the thermistor was not functioning properly on an intermittent basis. After it was replaced the refrig has worked well on either gas or electric. In very hot (100 degree) outside temps it stays in the high 30's to very low 40's in daytime and goes right down to 32 at night if set on highest level (5). We don't see any difference in performance between gas or electric except that it seems to take a little longer to get down to routine operating temp on electric.

[franklyfrank]

When the fridge is running on AC there is no burner noise. Correct?
We are also having subnormal performance on our current trip. In the past the stuff would be near freezing in the main compartment and lately it is barely cooling. AC or Gas same performance. The freezer is working normal.
Is there a maintenance routine I should perform ? We have a 2013 International.

[JCWDCW]

The gas flame heats the coils in the chimney. The electric heater wraps around the coils from the other side. Electric will always work as long as the ammonia gas system is properly charged and the trailer is level. Gas flame won't be effective if the chimney is plugged even if you have a good flame. What you are finding is pretty typical of a plugged chimney. You can try blowing it out with compressed air from the bottom. Also blow out the flame tube since particles land on the little burner and disrupt the flame. If you are handy you might try disassembling the chimney to clean it. This usually requires removing the complete fridge as I recall. Maybe better to let a Technician look at it. If you are low on refrigerant the whole unit has to come out to be leak-checked regardless.
JCW

[Streamracer]

My old 86 still cools about the same on both. I've added an old fan from a computer that blows up the back. I only turn it on when hot and the sun is baking on the side.

[cazual6]

I would recommend this wireless digital thermometer. This will give you both Fridge and Freezer temps.

[Jammer]

Originally Posted by CDONA

When did they stop making 3 way refers? I remember them back in the 70's, but new stuff is only 2 way, because of the big electrical hit running the 12 v heating element.
It can't be a ammonia issue for it runs on 110v. So it must be a controller module, burner fuel mixture or a propane supply issue.

You can still get 3 way fridges. They were never made in the larger sizes though and still aren't. The trend towards larger fridges has meant that most RVs have a fridge larger than the largest 3 way fridges being made. Yes, the only difference is the controls plus the presence of another heating element and the 12v terminals.

Another fact to consider is that the popularity of electronic spark ignition has eliminated the main problem with running the propane burner on the road because now it no longer matters if it blows out occasionally.

And finally.. in the sizes and situations where a small 3 way fridge makes sense, a Danfoss (12v compressor cooled) fridge now makes even more sense.

[comtnbyk]

we have the same problem this last weekend in our 68 Overlander. I will check the chimney and go from there.

[Airwave503]

Closing the loop on this. I had Dometic look at it and they said it was working fine and that I probably wasn't level enough. I saw in the documentation that the trailer had to be level for the fridge to work on Propane and I thought I was level enough. It was definitely level enough for comfortable camping.

In any case, after I got it back from Dometic, I was skeptical but I parked the trailer in my driveway and fussed around until it couldn't be more level. Sure enough, inside of 24 hours water was freezing in the freezer and the beers in the main compartment was ice cold.

[ijustlee]

Yes, gas fridges are very sensitive to level and often come with a bubble dot level to check the freezer floor or shelf with. It doesn't matter if using gas or electric because there is a puddle of ammonia in the freezer compartment pipes that evaporates and needs to be carried away by Hydrogen gas flowing downhill to make the cold. A delicate flow of several fluids and gasses needs to happen both inside and outside a gas fridge! Your fridge might have a slightly different location of level compared to the trailer floor so you should check the fridge itself for level. I'd like to meet the guy who was looking at a flame and said to himself " I bet I could take this flame and make my beer cold" !

[nvestysly]

Originally Posted by ijustlee

I'd like to meet the guy who was looking at a flame and said to himself " I bet I could take this flame and make my beer cold" !

It does seem a little counter-intuitive. If you consider energy in = energy out it makes more sense. Regardless of whether the input is a flame produced by propane (or an electric heating element) in your RV refrigerator versus an electric motor driving a compressor in a household refrigerator both use condensing and evaporating fluids to move heat from one area to another.

I think the flame powered refrigeration cycles have been around longer than electric-motor powered compressor cycles.

[franklyfrank]

Originally Posted by Airwave503

Closing the loop on this. I had Dometic look at it and they said it was working fine and that I probably wasn't level enough. I saw in the documentation that the trailer had to be level for the fridge to work on Propane and I thought I was level enough. It was definitely level enough for comfortable camping.

In any case, after I got it back from Dometic, I was skeptical but I parked the trailer in my driveway and fussed around until it couldn't be more level. Sure enough, inside of 24 hours water was freezing in the freezer and the beers in the main compartment was ice cold.

Our Fridge works perfectly even when the trailer is not level.
Our 2013 30' International is parked on our driveway with a steep incline. It is fairly level side to side but way out front to back, aprox. 10" lower in the front. Preparing for trips I turn the fridge on a couple of days ahead and within 24 hours it is ready to load up including a bag of ice in the freezer.
Never had a problem not cooling properly out of level this far in three years.

[Airwave503]

Originally Posted by franklyfrank

Never had a problem not cooling properly out of level this far in three years.

In propane mode? Cause yeah, fridge works fine on AC or DC when not level.

[Rocinante]

Our Airstream's service manager disagrees vehemently. Having repaired any number of Dometic fridges gone bad, he says with significant emphasis that if your trailer is parked, you either need to level it to make the fridge happy, or turn off the fridge. Not so while driving because the constant sloshing keeps things moving. He also says the damage done by running the fridge out of level can be cumulative. Something about crystals forming and gradually blocking the pipes.

So, for our two cents, we take the advice of a service manager with years of experience over anything anybody here says about how well their personal fridge works when parked out of level.

You don't have to do the same, of course, because it is your fridge not mine.


"When people show you who they are, believe them the first time." - Maya Angelou

[Mike1997]

Mind is an older RM4873 that works great except for the ice maker. Its never worked and I have not tried to fix it yet. Its a 3way and gets super cold on AC even on lowest setting. In fact sometimes I cut it off over night cause the bottle/cans freeze and veggies have ice on them.

Unless its an overnight trip on the road, I always level mine since its so easy. Just a push of a button and watch the bubble level.....easy as pie!!

[pflack]

I have the same unit in a 20' Argosy Minuet w/aluminum floors. If I get up at night, the gas recycles, that is the lights change and I can hear the pilot light trying to light? Never hear and sound from the fridge, either in shore power or gas mode??? I am totally confused.

[OTRA15]

Originally Posted by pflack

I have the same unit in a 20' Argosy Minuet w/aluminum floors. If I get up at night, the gas recycles, that is the lights change and I can hear the pilot light trying to light? Never hear and sound from the fridge, either in shore power or gas mode??? I am totally confused.

You realize that most of this thread is a couple of years old +/-?

If you want to get the attention of an earlier poster, it is best to Quote them via the button below and to the right. Then they will usually get an email alerting them to the quote.

Peter

[SteveSueMac]

Originally Posted by OTRA15

You realize that most of this thread is a couple of years old +/-?

If you want to get the attention of an earlier poster, it is best to Quote them via the button below and to the right. Then they will usually get an email alerting them to the quote.

Peter

Apologies for the hijack here - just a point of reference. I use the mobile app - search bars and orange arrows aren’t part of my experience (unless I’m missing something). And when anyone replies to a thread A regardless of age - it shows up in my feed of unread notes. I don’t know if that’s the same on the web or if that’s a setting I selected somewhere, but if I’m seeing it, wouldn’t anyone?

Thx!

[AtomicNo13]

One of our fridges is nearing 30 years old. I think it cools the same AC vs. gas.

[Burnside Bob]

Originally Posted by Airwave503

Now back home, I've had the fridge on gas for 48 hours in lower temps and more shade. It is cooling but definitely not as robust as when in AC mode. I don't think it should matter but the only other difference is that I have it in straight gas mode, not Auto/Gas mode.

My question is, should I expect the fridge to work as well on gas as AC? How about DC which I haven't tested yet (I have a very good AGM battery).

Also, was the high heat likely the culprit on my trips? Thanks in advance.
--Jason

Hi Jason:

I live not to far from you so our 2009 Dometic 3762 two way frig has experienced the same summer conditions as your unit.

Ours works very well on either AC or Propane, holding 32 to 33 degrees in the refer compartment. When at home I set it to 'Auto', but if the AC is interrupted it defaults to Propane. It will not switch back to AC after an AC interruption. During that prolonged period of 90+ degree weather we blew thru a 30 lb cylinder of propane on 'Auto' in short order because I forgot to reset operation to 'Auto' from propane after returning from a weekend trip.

I'm not familiar with your model, but ours has 5 temperature settings. On the warmest setting it behaves pretty much as you have described. So I would review the owner's literature to see if you can adjust the operating temperature. We run on the coldest setting as there is no internal air circulation--warm food doesn't cool very quickly and we'd rather risk a little frozen lettuce over spoiled food.

In most places you can't hear our unit operating on propane. At night you can hear the gas solenoid click and the burner light, but only if it is dead quiet.

Since your unit works well on AC, functionally it seems OK. Perhaps the flame is not in the right spot or not hot enough. Your owner's literature may discuss where the flame needs to be positioned and how to adjust flame size.

I hope these comments help.