Dometic Refer Fridge Portion not Cooling

[Gkaiser]

I did a search to find this issue but turned up minimal.

I have a 2011 Keystone Cougar 328 with a Dometic Refrigerator.
The Freezer part seems to be cooling fine, but the Fridge might get down to a temp of 70. very minimal cooling. It also only seems to work on Gas.

I replaced the main Circuit board. and no change.
The Heating element is giving me a 44 ohms rating.
I have a new Thermistor, but haven't had a chance to install yet.
I did notice that the upper circuit board, If I touch the power switch just right it error light pops up.

I assume I will need to replace the upper board as well. Is there a good way to test this board?

I did read to check for an obstruction by taking the roof vent off.
I do have a very serious dirt dobber / Wasp problem in the summer time around my property.

Just looking for any other thoughts.

[cbr46]

I could use some help also . . . .

Over last weekend my fridge (Dometic 2852) ran up to ~58F but more commonly in the 48F range (when I get concerned). Normally the high temp is 44F and low 40F. Outside temp was a sweltering 95F with the Sun shining on the fridge side of the Class A RV. Inside the AC was keeping a cool 80ish until the Sun went down. Fridge was running on AC as long as the generator was running. Before the trip it seemed to take a long time to cool down to operating temp (overnight). Control board is the Dinosaur PCB (original fried a long time ago). I think the temp setting is on "4". Still some room to go. On Day 2 & 3 outside temps relaxed a bit but the fridge still seemed to struggle in the 44-48F range.

Thermistor is aging and wasn't keeping the fridge in range so 6 months ago I soldered a resistor across it. Yes, I'm that cheap. It just means the temp range is narrower.

So this week I started investigating and running some tests. Fridge temps ranged from 40-44F. Freezer was a good 0 to -2F. PERFECT! But highest outside temps were 85ish. There was one point where it didn't seem to run. Reinserting the eyebrow control connector on the PCB seemed to make it work again. I couldn't reproduce the problem (could this be my entire issue? don't know). During testing the element or flame was on more than I expected.

Door seals look ok. There is surface rust along the bottom seal.

There's no sign of any coolant leaks or ammonia smell. Intake is clear and top fins are clear. Top shroud is a Camco and doesn't seem to breathe as well as the original. With the shroud off there's lots of heat coming out! No, I can't run a fan to help it as most weekends I'm boondocking. Flame appears good? but there's considerable rust around the bottom of the flue.



I started to pull the fridge out (really don't want to) to clean the flue but not sure that will improve my heat transfer to the heating tube. Besides, it didn't do very well in AC mode.

I use the RV about 2 weekends / month. Sometimes more, sometimes less.

I doubt we'll see high temps until next year, so can't effectively test any fixes.

Thoughts?

Best,
- bob

[dougrainer]

Gkaiser wrote:
Replaced Eyebrow Board. Fridge now works on electric, and the temp this morning was 30deg. so now it's over cooling. just needs the thermistor adjusted down to dial in a good temp.

So all problems fixed. seems like it was just the power switch all along, but now it has all new circuitry top to bottom. ~$180 total on amazon.

Model is a DM2852RBX

Well, you have not followed the advice. Good to know that the CU is good. You should have the Auto Temp model. You slide the Thermister up and down on the fin to change the set temp. It is usually about 4 degrees. NOW, IF you had followed my advice, you could have spent your money better. You could have purchased the eyebrow, with the adjustable 5 position Temp, and your refer would NOT be a AUTO temp refer. Doug

[Gkaiser]

Replaced Eyebrow Board. Fridge now works on electric, and the temp this morning was 30deg. so now it's over cooling. just needs the thermistor adjusted down to dial in a good temp.

So all problems fixed. seems like it was just the power switch all along, but now it has all new circuitry top to bottom. ~$180 total on amazon.

Model is a DM2852RBX

[dougrainer]

Gkaiser wrote:
Doug,

Left running overnight with newly installed thermister. Freezer is at 10° fridge was cold below 50° but had to get to work, didn't have time to wait for the thermometer to fully read. But it is definitely colder than it was getting before the thermistor install.

SO I believe my only remaining issue is why will it not flip over to electric?
I checked the output voltage at Jumper 7 and 8 (I believe it is)and was not getting 120 but I am getting 120 though the fuse. I still believe I need to replace the upper control board.

If I am not getting voltage to the heating element why hard wire it? you got to start at the source and work your way to the end. if I am getting voltage to it, and its still not cooling well then yes I need an element, but right now I am not getting power to the leads.

Look, you are a new member. So, you may not know who various people are that respond. I have 41 years as a RV Tech and I am Master Certified. So, your statement, "Start at the source and work your way to the end". Really? Now, WHY replace parts if you do not know if the Cooling unit is to spec?????? DO AS I SAY----Wire the 120 element for 24 hours as I explained. THIS IS WHAT I WOULD DO IF YOU CAME TO MY SHOP WITH YOUR COMPLAINTS. I would worry about controls only if the CU checked out to spec. Doug

[MEXICOWANDERER]

Water will freeze solid at 28F

Thirty degrees WARMER than what is normal.

Refrigerator running at 70F ?

Thirty degrees warmer ?

Get the picture ?

BAD

COOLING

UNIT

Now how much money did you waste that could have been applied aginst the correct repair?

[Gjac]

You have gotten good advice so far the only thing I would add to help your issue is to check the connection from the eye brow to your control board. When mine would not switch I cleaned the contacts with an eraser on the board and it allow the eyebrow switch to work again. Also is rust from your flue blocking the slots on your burner tube when on propane or are the slots rusted out causing a poor flame?

[Kappy54]

Dometic 12 cu double door temperature can be resolved by moving the thermistor to a cooler region of your fin coil.

[Kappy54]

I purchased a new 2019 Grand Design 336RLS. Plugged into house current and the fridge on the coldest setting was all over the place. I call the service department and they had a similar problem Dometic and were puzzled. The service department had me reset to level 3 and instructed me to leave it closed for three hours. It held temp until my wife put our food in for our first trip. Very frustrated! I'll fast forward to my fix. I did an internet search for "What is the function of a thermistor". The importance of an article about moving the thermistor.
Doing The Thermistor Shuffle – RV Refrigeration Repair
https://rvrefrigeratorrepair.com/uncategorized/the-thermistor-shuffle/

I pulled the thermistor out of its ceiling mount an placed it facing the coil on my top shelf "lower left corner of my fin coil".
Perfect 34 degrees at level 4 and holding!

[Old-Biscuit]

Gkaiser wrote:
Doug,

Left running overnight with newly installed thermister. Freezer is at 10° fridge was cold below 50° but had to get to work, didn't have time to wait for the thermometer to fully read. But it is definitely colder than it was getting before the thermistor install.

SO I believe my only remaining issue is why will it not flip over to electric?
I checked the output voltage at Jumper 7 and 8 (I believe it is)and was not getting 120 but I am getting 120 though the fuse. I still believe I need to replace the upper control board.

If I am not getting voltage to the heating element why hard wire it? you got to start at the source and work your way to the end. if I am getting voltage to it, and its still not cooling well then yes I need an element, but right now I am not getting power to the leads.

Because directly wiring the element BYPASSES ALL controls and will PROVE if cooling unit is good or bad......SIMPLE

Last time........MODEL of Dometic??

[Gkaiser]

Doug,

Left running overnight with newly installed thermister. Freezer is at 10° fridge was cold below 50° but had to get to work, didn't have time to wait for the thermometer to fully read. But it is definitely colder than it was getting before the thermistor install.

SO I believe my only remaining issue is why will it not flip over to electric?
I checked the output voltage at Jumper 7 and 8 (I believe it is)and was not getting 120 but I am getting 120 though the fuse. I still believe I need to replace the upper control board.

If I am not getting voltage to the heating element why hard wire it? you got to start at the source and work your way to the end. if I am getting voltage to it, and its still not cooling well then yes I need an element, but right now I am not getting power to the leads.

[dougrainer]

Gkaiser wrote:
Freezer is cold enough to freeze the milk i put in there to keep it cold.

Replaced thermistor - now retesting.
Also checked voltage at board for heating element and sill getting low voltage with new board.

Could eyebrow board be bad also and not signaling the main board to go electric?

So 2 problems 1 fridge isn't cooling and 2 it only works as gas. Either in gas only or auto mode. It goes to gas.

The Operating temp of a freezer is 0 to 10 degrees. Milk will freeze at about 30 degrees. So, using the COLD temp of your freezer by gauging the milk freezing without an actual temp is not the way to go. If you want, continue throwing parts and spending money. OR YOU COULD DO WHAT I TOLD YOU. HOT WIRE THE 120 ELEMENT FOR 24 HOURS AND SAVE SOME MONEY. Doug

[Old-Biscuit]

Actual Model of that Dometic would be helpful

120VAC issue....
Voltmeter
Check voltage at receptacle fridge power cord plugs into
Check voltage ON circuit board where AC Power connects
Check voltage on BOTH sides of the AC FUSE (3a/5a Glass fuse)...make sure Fuse and clips are passing fully voltage
Not recognizing that AC IS available in AUTO Mode could be issue with that Upper display board

Freezer cold...food compartment NOT
Could be circuit board not allowing FULL heating cycle
Could be gas flame NOT generating enough vapor ammonia to allow for full cooling effect (burner clean/flue clean----strong blue flame that just reaches up into bottom of flue)
BAD cooling unit......obstruction between freezer low temp evap coil and food compartment high temp evap coil (freezer cold/food NOT----CLASSIC symptom)
*****As suggested by DOUG remove heater element leads from circuit board and plug DIRECTLY in the 120VAC outlet....both compartments WILL get cold IF cooling unit is functioning properly. Then the issue is with 'controls'
If food compartment does NOT get cold...then bad cooling unit
Simple test and FrEE

[Gkaiser]

Freezer is cold enough to freeze the milk i put in there to keep it cold.

Replaced thermistor - now retesting.
Also checked voltage at board for heating element and sill getting low voltage with new board.

Could eyebrow board be bad also and not signaling the main board to go electric?

So 2 problems 1 fridge isn't cooling and 2 it only works as gas. Either in gas only or auto mode. It goes to gas.

[DownTheAvenue]

Unit level?