Can this really be correct on my fridge?

[JWood422]

Originally Posted by NXR

So the fans have power and ground but are not spinning?

I've never seen a fan with its own temperature switch built in but maybe... That would make them more expensive so I'm doubting they do.

Can you get a stick in there and see if the fans will turn? They may be bound up. You may only have had one fan working for a while and it finally failed.

You may also be able to blast some air down there from a hair dryer or a compressor to see if that will spin the blades. It won't matter if they spin backwards for the test.

Ray

This seems to have a thermostat.

https://www.dometic.com/en/se/produc...r-vkit-_-31166

[NXR]

Originally Posted by JWood422

This seems to have a thermostat.

https://www.dometic.com/en/se/produc...r-vkit-_-31166

Look at the second picture. You'll see a clip-on thermostatic switch. That probably is on one of the coolant pipes.

But since the fans are getting power, presumably from that switch, that lends more strength to the fans being bad.

Ray

[Scrapper]

Originally Posted by NXR

So the fans have power and ground but are not spinning?

I've never seen a fan with its own temperature switch built in but maybe... That would make them more expensive so I'm doubting they do.

Can you get a stick in there and see if the fans will turn? They may be bound up. You may only have had one fan working for a while and it finally failed.

You may also be able to blast some air down there from a hair dryer or a compressor to see if that will spin the blades. It won't matter if they spin backwards for the test.

Ray

Computer case fans have had built-it thermistors for years. These same fans are used on the back of Dometic refrigerators. Inexpensive case fans use oil impregnated bronze bearings instead of ball bearings. Bronze bearing fans can fail within a year or two. Really cheap case fans use brass bearings which may fail at any time, sometimes within a year. Brass and bronze bearing fans do not have built-it thermistors. Not all ball bearing fans have built-it thermistors, they are usually connected to some type of temperature control, but not all of them are.

[JWood422]

In my infinite wisdom, I realized I’ve been checking the freezer section only and not the fridge section. The fridge is staying at a reasonable consistent temp of 39*-41*. So I figure the issue is with the freezer and not the entire unit.
I called Dometic customer support. She suggested I test the freeze door gasket by closing the door onto a dollar bill and seeing how much resistance I felt when pulling it out. Probably not enough. She sent me 4 documents, one of which is how to rejuvenate the gasket. I plan to try that tomorrow.
She also confirmed the fans run only when the thermostat senses a certain temp. So not running does not necessarily mean the fans are bad. I’ll have to wait and see when the weather warms up.
I’ll keep y’all posted.

[JWood422]

We’re having a warmer day today. The fans came on at least twice today. Once while I was in the trailer. They sound pretty dang good to me! The freezer temp seems to stay lower with the fans running. I do wish they would run longer. My next step is the ice cream test. I’m gonna see how solid it stays. To me that should really tell me just how well the freezer is working.
I used my instant read thermometer in a bottle of water to check the fridge. The water is right about 38*. Seems pretty good to me.
I also rechecked the gaskets using a dollar bill. (I can’t afford any higher denomination). I think they’re ok for now. Plus the gaskets are OMG hard to pull out. I’d rather not do more harm than good of the gaskets aren’t the problem after all.
Thanks for reading!

[rracer5]

Originally Posted by JWood422

We’re having a warmer day today. The fans came on at least twice today. Once while I was in the trailer. They sound pretty dang good to me! The freezer temp seems to stay lower with the fans running. I do wish they would run longer. My next step is the ice cream test. I’m gonna see how solid it stays. To me that should really tell me just how well the freezer is working.
I used my instant read thermometer in a bottle of water to check the fridge. The water is right about 38*. Seems pretty good to me.
I also rechecked the gaskets using a dollar bill. (I can’t afford any higher denomination). I think they’re ok for now. Plus the gaskets are OMG hard to pull out. I’d rather not do more harm than good of the gaskets aren’t the problem after all.
Thanks for reading!

Just make sure that if you have to shim the gasket, use $5 bills. Don't go cheap on that. After all you get what you pay for.....

[JWood422]

Originally Posted by rracer5

Just make sure that if you have to shim the gasket, use $5 bills. Don't go cheap on that. After all you get what you pay for.....

Man, seriously. Thank you for this! Sometimes a little comic relief does a person a world of good!

P.S. The ice cream is still firm.

[JWood422]

The freezer failed the ice cream test tonight. I refer to it as soft serve. Not good.
The weather turned cool today. I honestly believe the freezer stays colder when the weather turns warm which causes the fans to come on.

[pgandw]

I don't have the same model Dometic fridge. But I found that cooling was not as consistent as I thought it should be, despite fixing the propane exhaust, properly insulating around the fridge, and adjusting the baffle to Dometic installation specs. I found the cooling fan mounted down in the throat between upper and lower vents only came on under the hottest conditions, and was noisy (sounded like dry bearings) when it did.

I tried removing the fan but just couldn't reach the throat area without some major surgery. So I mounted 2 12V 120mm 1200 RPM computer case fans directly to the top grill and wired them to a switch near the converter. The computer case fans are super quiet, and keep the temps down enough that the OEM fan never comes on. The fridge is a lot more consistent on temp. The 2 computer case fans together are 140ma, or 3.4AH per 24hr day.

I also broke down and added a Camco D-cell powered fan for the fridge interior. Expensive ($20) but perfect size for my 3cuft fridge. Now I get less than 3 degree variation in the fridge even when accessing the fridge frequently.

just our experiences
Fred W
2019 Flagstaff T21TBHW A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time

[JWood422]

Originally Posted by pgandw

I don't have the same model Dometic fridge. But I found that cooling was not as consistent as I thought it should be, despite fixing the propane exhaust, properly insulating around the fridge, and adjusting the baffle to Dometic installation specs. I found the cooling fan mounted down in the throat between upper and lower vents only came on under the hottest conditions, and was noisy (sounded like dry bearings) when it did.

I tried removing the fan but just couldn't reach the throat area without some major surgery. So I mounted 2 12V 120mm 1200 RPM computer case fans directly to the top grill and wired them to a switch near the converter. The computer case fans are super quiet, and keep the temps down enough that the OEM fan never comes on. The fridge is a lot more consistent on temp. The 2 computer case fans together are 140ma, or 3.4AH per 24hr day.

I also broke down and added a Camco D-cell powered fan for the fridge interior. Expensive ($20) but perfect size for my 3cuft fridge. Now I get less than 3 degree variation in the fridge even when accessing the fridge frequently.

just our experiences
Fred W
2019 Flagstaff T21TBHW A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time

Thank you! I was already considering adding new fans right where you said. I’ll look in to those specs.

[JWood422]

I attached 3 computer fans to the upper cover tonight. The false wall that covers half of the fins made installation quite the challenge. (I’ll do my best to get pictures of how I attached them. I’m pretty sure no one would have said to do it the way I did.)I was able to extend the power wires down to where the power connection is. I’ll figure how to hook it up tomorrow. I was able to confirm that the fans really are moving air out. We shall see!

[JWood422]

I * finally* hooked up the fans to power today. They’re humming nicely now. The weather has warmed up so even the “official” ones that came with the trailer are running. But I could still feel warm air coming out of the vent even before the original fans came on. I put some ice cream in to see how well it stays firm. (Bryers Reese’s Peanut Butter Cup.) Right now the temp is staying between 2&3*. But it’s really too early to tell if what I did will do any good.
On a side note, if anyone needs help making a simple job far more difficult and complicated than it should be, I’m your man. Seriously. I have no idea why I’m so good at that.

[JWood422]

No joy, y’all. Temp is still fluctuating. It’s up to 21* now. GRRRRRRRRR!!!!

[NXR]

It's not in the "every 49 hours" defrost cycle, is it? If so that's not abnormal. If you turn the fridge off for 30 seconds and turn it back on, that resets the 49-hour clock and immediately restarts the cooling unit.

if you do that and the temp starts to drop in an hour or so it was in the defrost cycle.

Ray

[JWood422]

Originally Posted by NXR

It's not in the "every 49 hours" defrost cycle, is it? If so that's not abnormal. If you turn the fridge off for 30 seconds and turn it back on, that resets the 49-hour clock and immediately restarts the cooling unit.

if you do that and the temp starts to drop in an hour or so it was in the defrost cycle.

Ray

My fridge does not defrost itself.

[TimVWulp]

Had the same problem with my dmr 702 refrigerator. Talked with a domestic tech at 2019 frog rally. He said the temperature sender is shorted out and that the fridge temp will go from 40-45 degrees to 30-25 degrees with a bad sensor.
This fridge dose not have the standard temperature sensor that clips to the cooling fins. It has a thermistor that is a round bulb located below the cooling fins in the refrigerator. I replaced the sensor and the fridge temp holds at 33-38 deg and the ice cream is hard. Ice cream will start to melt About 16 deg

https://www.arprv.com/rm3762-dmr702....-fridge-sensor

Hope this helps Tim

[Rich5117]

I notice in your original photo the wood panel, but do not see any baffle at the top of the frig. Is this void space open completely at the top of the frig? If this is the case you will need to install a baffle to keep the heat from that space. This will reduce the heat load on the freezer area.

The freezer section of your refrigerator is not independently controlled it is cooled as a result of your lower section working properly. According to your temps provided the lower sections seems ok.

If you have access to an infrared thermometer take the temperature of the back wall of your freezer while the unit is operating the temp should be in the negative, mine runs at negative 16F. The lower section fins stay around 20F.

There is a test that you can do for 24 hours that keeps the unit running fully for that time. This is done by disconnecting the thermistor wires on the control board. Although, according to your posts it does not seem that cooling is the issue. It does seem like a heat load issue.

Also Ice cream is meant to be kept at 0 to -10 degrees F anything above this will allow the ice cream to get soft. It actually serves best between 6 and 10 degrees F Might not be a really good test food.

[JWood422]

Thanks, y’all. I’m gonna reread the entire thread and see what I’ve missed. The answer is here somewhere. (It would be helpful if I weren’t so good at making things hard for myself.)

[JWood422]

If anyone is still interested I have an update. I added additional insulation above the refrigerator from the outside access. I also redirected the fans because I felt like they were not blowing the air out. It’s very cramped in there and I have a hard time getting the fans exactly where I want them. In fact, it’s so difficult that I can’t even take a picture of what I’ve done because it takes three hands to do that. So I’m lucky to be able to get them in the way I want them without taking pictures.
I can now feel very warm air coming out of the top slot of the vent. Before I redirected the fans I wasn’t able to feel all that much warm air. But it’s a good flow of warm air even though they are small 12 V fans.
The temperature has dropped from 32° to 19° in about 45 minutes. Wish me luck!

[Rich5117]

Yes we are always interested in how problems get resolved. The area above our fridge was completely open as well I put foam insulation in and created a baffle out of Luwan plywood and sealed it so no hot air could go in that area. The hot air has to go out the vent.