Fridge Follow-Up

[FastEddieB]

In my "Toilet Trouble" thread, I mentioned problems we were having with our Dometic fridge in our 21BHS. In short, increasing noise followed months later by failure and an E3 code.

I know shockingly little about refrigerators in general, so excuse me if I get something wrong below.

The shop said the trailer was ready - new toilet, fixed fridge and a small leak on the roof patched. I was told the fridge problem was two possibly bad thermal sensors, which they had in stock. When replaced, the fridge ran, but quit when you pushed against the back - consistent with my observation that the propane seems to fire in response to my pushing against it. That was traced to a loose wire leading to the fan motor circuit board, which was repaired.

But when we went to pick up the trailer, the fridge had faulted again. Further diagnostics revealed that the fan motor circuit board was fried, and the fan unit needed replacing. They further said that the fan appeared to be wired improperly, getting its 12v from the hot side of one of the thermal switches so that it was running all the time. They ordered a new fan unit and a thermally regulated switch so the fan would only operate above a certain temperature.

Again, this is just what we were told. We're supposed to pick it up in a few days, though its ready now. I'll report back if everything works as its supposed to. Mainly wanted to give everyone a head's up if, in fact, our fan was wired wrong - we may not be the only unit to leave the factory like that.

[Capt J-rod]

If you read up on our fridge it struggles to keep up on the hotter days running on electricity. I do HVAC for a living and understand refrigeration better than most. Our fridge uses heat and fire to make refrigeration. It is confusing as hell, but it really does work. These units work well on propane due to the higher Btu's. the electric element is rather small for the application. Installation is very key to these units working well. Many of us, myself included added a second fan behind the fridge and I also built an air scoop to help with the airflow. I also have a secondary switch that I can make the fans run continuous. It works OK at best. When it is hot outside I just let it run on propane. When it is cooler out below 70, or night time when the sun is off the trailer, then I let electric run.

[FastEddieB]

We're picking up the trailer tomorrow.

As background, it had been sitting up at our Lenoir City, TN property for at least 6 months, serving as a "construction trailer" as it were.

The fridge has been running on shore power for the entire time. In the heat of the summer it always managed to keep the fridge temps between about 34° and 39°. In spite of the moaning and groaning.

It has also been brutally cold at times. We've visited the trailer at temps near 20°, and the fridge still kept temps in the same range, leading us to believe it must also heat when temps drop below a certain point.

I'll let you know if the repair was successful in a few days.

[ADR]

Have never seen a RV fridge with any kind of heat.   
Quite curious how in extended below freezing weather with presumably no heat in the camper it managed to not freeze inside....

[tinkeringtechie]

It has also been brutally cold at times. We've visited the trailer at temps near 20°, and the fridge still kept temps in the same range, leading us to believe it must also heat when temps drop below a certain point.

It's still an insulated box. It probably won't heat it, but the same insulation that prevents heat from entering also prevents heat from escaping.

[FastEddieB]

Picked up the trailer yesterday.

The old fan certainly does appear to be toast:





It was allegedly shorting out the wire to the controller board and causing the fault.

The fridge is now working fine with zero fan noise. I'll follow up shortly with a photo of the rewiring they did.

[FastEddieB]

As wired before, the fan ran continuously. I can attest to that because as the noise increased it was constant, even on cold days.

Now, it's supposedly wired directly to 12v, but through a thermally controlled switch so as to only come on when needed. It is holding temp and blissfully silent at least up to about 60° outside.

I can only hope it's all done properly.

[Capt J-rod]

There is a thermostat that determines when the outdoor fan comes on. I don't remember the temperature ranges off hand, but they make a stat that makes it come on sooner. FWIW it looks like someone's solution tho the fridge not cooling was to just wire the fan on 100% of the time thus the melt down. It is now wire through the stat like it was from the factory. Be sure to keep an eye on the box temps this summer as the temps creep up and the fridge is in the sun. My trailer is black which doesn't help. if the temps creep up then switch to propane.

[MitchB]

Couple questions, first, which fridge model are we talking about? Second, is the outside fan standard?  I don't recall seeing one on mine.

[FastEddieB]

Couple questions, first, which fridge model are we talking about? Second, is the outside fan standard?  I don't recall seeing one on mine.

Here's my data plate:



I think the fan was stock, and that it's somewhere above the fridge, accessible from the upper outdoor access panel.

[Merlin]

Couple questions, first, which fridge model are we talking about? Second, is the outside fan standard?  I don't recall seeing one on mine.

I don't have an outside fan on my 3-way Dometic single door fridge. FastEddieB has the larger 2-way double door fridge. I'm adding an outside fan this spring to help the air circulation in the outside coils. Hopefully it will work better and have higher efficiency. The fan I bought has a built-in thermostat.

[djsamuel]

I have the same model as Fast Eddie in my 2013 21BHS. No fan in my installation.

[FastEddieB]

I have the same model as Fast Eddie in my 2013 21BHS. No fan in my installation.

Weird.

[ADR]

One thing I've noticed after many years of RV's and absorption fridges-
The ones that vent the heat straight up through the roof seem to always work better than ones that have the intake and exhaust vent on the flat wall.

The chimney effect of the through the roof vent seems to move enough air naturally to rarely need a fan.

In my experience every one  I've owned that vent the heat through the wall need fans.


I've also seen quite a few that were not installed properly per manufacturer requirements.    Especially important on the through the wall install is to not create any dead spots in the flow. 
A common fault, that my Rpod had, was the compartment went several inches above the top of the wall vent.   That is specifically pointed out as a problem in many install docs.

[MitchB]

Thanks, have to do some investigating.