Forum Discussion

jillhop's avatar
jillhop
Explorer
Apr 01, 2017

Refrigerator thinks it's a freezer ...

My trusty RV tech went off to Florida for the winter, so I had to try out a new guy to deal with an issue that I was having with my refrigerator intermittently not lighting on gas. In the course of working on that issue (which I actually think is a corroded wire between the main board and the ignitor), he removed my main board and replaced it with what I think was another random used board. Since then, the refrigerator will only run if it is over 40 degrees outside (despite running a space heater in the coach with the refrigerator door open leading to 60 degrees in the refrigerator...) and when it does run, within 6 hours the temperature in the refrigerator is down to 10 degrees. Thankfully, my regular RV tech is back from FL and is going to put a new control board in tomorrow, but I have some questions in advance.

Thinking about it, the refrigerator is acting like the temperature sensor is sensing the OUTDOOR temperature, not the temperature in the refrigerator. Is this possible??? The normal temperature sensor looks like it is in place inside the refrigerator, attached to the plastic bracket on the fins at the back of the refrigerator.

Or, could it just be a bad controller board?

I have used this refrigerator many times in the past in cold weather below 32 degrees. Once we get this sorted out, we will get to the original issue of not lighting intermittently on gas ...

Any ideas/comments on this would be appreciated. The refrigerator is (I believe) the original refrigerator in my 1998 Coachmen Class C, Dometic Model RM 2652.
  • dougrainer's avatar
    dougrainer
    Nomad
    Apr 01, 2017
    tinstartrvlr wrote:
    "If the thermister were not connected back to the control board, would the board somehow be able to sense the outdoor temperature?"

    Geez would you stay out of my head! :) That is another exact thing that I asked and could not get an answer.

    Some of the answers I have gotten for the problem:
    From Dometic:

    1. fridge not installed properly in the cabinet
    2. the cooling solution gels/freezes in cold weather

    From a tech:
    1. thermister should be located next to the fins, not where it currently is (Dometic disagrees)
    2. bad control board

    As I said, no answers yet to the same questions you ask.



    1.GEL only happens is sub 15 to 20 degree ambient temps. You then use a 60 watt light bulb at the rear cooling unit area to help the ammonia solution to not gel.
    2. Thermister should ne ON the fins
    3. in 37 years as a tech, I have NEVER had or heard of a refer NOT running in temps above 20 degrees ambient, but will when warmer than that.
    4. Uninformed people think control boards always go bad. In the past 20 years(dometic), control boards rarely go bad. It is the other electronic items that fail, that the board relies on. Control boards will not cause a failure to run when cold and run when warmer.
    5. A Temp Thermister can OHM out good but still be defective. SO, The temp Thermister is a cheap way to replace a suspect part. OR dunk the Thermister is a very warm glass of water and see if the refer starts in sub 30 degree weather. Doug
  • jillhop's avatar
    jillhop
    Explorer
    Apr 01, 2017
    Sounds like we have the same problem, tinstartvrlr!

    Have you tried replacing the thermister? From the manual that Old-biscuit posted above, it does sound like the thermister is the most likely suspect. I asked about the control board (lower board) because it was changing that board that started this issue for me.

    I know that my refrigerator is installed correctly in the cabinet, because for the past 2 1/2 years (and probably for the entire 19 years that this coach has been in use) it has worked fine. Same for the answer about the coolant freezing...

    I will keep this thread updated with what I try/find out. :-)
  • tinstartrvlr's avatar
    tinstartrvlr
    Explorer
    Apr 01, 2017
    "If the thermister were not connected back to the control board, would the board somehow be able to sense the outdoor temperature?"

    Geez would you stay out of my head! :) That is another exact thing that I asked and could not get an answer.

    Some of the answers I have gotten for the problem:
    From Dometic:

    1. fridge not installed properly in the cabinet
    2. the cooling solution gels/freezes in cold weather

    From a tech:
    1. thermister should be located next to the fins, not where it currently is (Dometic disagrees)
    2. bad control board

    As I said, no answers yet to the same questions you ask.
  • jillhop's avatar
    jillhop
    Explorer
    Apr 01, 2017
    I completely agree, Dougrainer, this guy will NEVER touch my coach again... besides screwing up the refrigerator, he disappeared with a part from my generator and wouldn't return calls or texts for 2 months. I had to ambush him at his regular workplace--the service dept. of the largest RV dealer in my area... but that is water under the bridge at this point.

    If the thermister were not connected back to the control board, would the board somehow be able to sense the outdoor temperature? That's the really confusing thing--the fridge won't run at all (on electric or propane) when the outside temperature is below 40 degrees, but if it's below 40 it turns into a freezer.
  • tinstartrvlr's avatar
    tinstartrvlr
    Explorer
    Apr 01, 2017
    "Thinking about it, the refrigerator is acting like the temperature sensor is sensing the OUTDOOR temperature"

    Those were my exact words to Dometic and the most recent tech I tried to get to repair it. I had to throw out a whole fridge full of food because temps outside were in the high 20's-low 30's and the fridge wouldn't even turn on/try to cool. Nothing. But when its 90 degrees outside, food in the fridge is borderline frozen. Thermometer shows 26-28 in the fridge, 0-5 in the freezer.

    And I still have no answers. I hope you find a solution. Please update if you do.
  • dougrainer's avatar
    dougrainer
    Nomad
    Apr 01, 2017
    I have NEVER had a Main control board cause Cooling problems or freezing problems. Are you positive he connected the temp Thermister back correctly and IS connected to the board. I do not understand why ANY so called RV tech would install a USED part on a customers coach. NOT professional and I would NEVER use such a parts changer again. You then have TOO many variables that may cause a problem. Maybe the Board is NOT correct for your refer. Maybe he did something wrong besides using used parts. Doug
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Apr 01, 2017
    A faulty thermistor causes fridge to 'run' continuously due to lack of temperature sensing for thermostat -----food compartment temps control 'cooling cycles'

    Manual..PG 9 'Limb Mode'

    Dometic thermistor FIX


    I would use a Dinosaur Electronics control board as replacement (check Serial number on Fridge for correct Dino Board)

    RM 2652 "Americana"
    921144001 - 921144064 Micro P-711
    921144101 - 921144140 3850415.01
    921144142 - 921144167 3850712.01

    Dino Bds

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