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jeffn74's avatar
jeffn74
Explorer
Feb 07, 2022

Dometic DM2852 Not working on AC

Hi,

My Dometic DM2852 fridge is not working on 120VAC. I have an LP leak so I have not confirmed that the fridge is working on LP. I am waiting for my new regulator and pigtails to arrive.

Anyway, I have checked the following
1. 12V is OK the lower board. Fuse is good.
2. 120VAC is OK the lower board. Fuse is good.
3. Heater element is 42ohms. Appears in spec.
4. NO 120VAC at the heater element measured on the board.
4. The eyebrow board has a finicky GAS button. It sticks a little.
5. Measurements of the P1 connector when attached to the lower board show...
RED is ground
Orange is 12V
Black is 12V
Green is 12V

Does it make sense for the black and the green to both be at 12V? I expected the black to be 12V when selecting 120VAC and the green to be 12V when selecting LP.

Is there a way to bypass the eyebrow board to force 120VAC operation? For example, tie P1-3 (black) directly to 12V and check to see if the 120VAC appears at the heater element (the eyebrow board will be disconnected from the lower board while performing this test).

I am suspecting a bad lower board, but I want to confirm this before buying a new one.

Any help is appreciated. Thanks!
-Jeff
  • bob213's avatar
    bob213
    Explorer
    Feb 08, 2022
    On mine there is a resettable thermal switch (2 red wires) on the stack. Try resetting that. Could be hidden with insulation.

    thermal switch.
    video start at 1:43
  • jeffn74's avatar
    jeffn74
    Explorer
    Feb 08, 2022
    Thanks. I tried the thermal fuse with no change.

    I have 12V on the board so the fuse is okay.
  • enblethen's avatar
    enblethen
    Nomad
    Feb 08, 2022
    If you have 120 volts to the fuse and no output to element, then good chance the relay on the circuit board has failed.
  • dougrainer's avatar
    dougrainer
    Nomad
    Feb 08, 2022
    Connect the 2 wires for the 120 element(remove from the board) and just connect to any 120 Black and White 120 source. leave for 24 hours. If the refer operates to temp your element is good and the Cooling unit is good. BTW, 120 elements either work or they do NOT. There is no partial operation of a 120 element. Doug
  • jeffn74's avatar
    jeffn74
    Explorer
    Feb 08, 2022
    Thanks for the comments. I will hardwire the 120VAC to the heating element and see what happens. I will let you know.
  • jeffn74's avatar
    jeffn74
    Explorer
    Feb 08, 2022
    I got a little anxious and decided to check the temperature inside the fridge after a few hours. The freezer is at 22F and the outside temp is 62F. The heater element and cooling system appear to be working fine. I will let this run for the prescribed 24hrs.

    I ordered a lower board today and it should arrive tomorrow. Any other ideas? Thanks!
  • dougrainer's avatar
    dougrainer
    Nomad
    Feb 08, 2022
    jeffn74 wrote:
    I got a little anxious and decided to check the temperature inside the fridge after a few hours. The freezer is at 22F and the outside temp is 62F. The heater element and cooling system appear to be working fine. I will let this run for the prescribed 24hrs.

    I ordered a lower board today and it should arrive tomorrow. Any other ideas? Thanks!


    Freezer temp is 0 to 10 degrees. Refer temp will be 26 to 38 degrees. I would suspect the eyebrow more than the rear control board, because you state the Gas button is finicky. What year is your refer. Doug
  • jeffn74's avatar
    jeffn74
    Explorer
    Feb 08, 2022
    The freezer was only on for a few hours when I posted my first measurement. I just checked it again and it is now down to 10F in about 7 hours. Tomorrow morning it should be nice and cold and I will measure it again.

    I am not sure if there is a datecode on the unit, but my RV is from 2012.

    I was thinking of the eyebrow board as a possiblity, but I need some more ideas of how to diagnosis that board.
  • jeffn74's avatar
    jeffn74
    Explorer
    Feb 09, 2022
    I took another set of measurements this morning. The fridge has been running for 24hrs. The freezer is at -2F and the fridge is at 14F. The cooling unit and heating element are definetely working properly.

    I unplugged the heating element and opened the door so that it warms up. I will need the fridge to be warm in order to verify the operation of the new lower board. The lower board should arrive today and I will update you with any results.
  • jeffn74's avatar
    jeffn74
    Explorer
    Feb 10, 2022
    Update on the issue...

    I installed the new board and am having the same problem (no cooling with 120VAC). At this point I need to look at the wiring and the eyebrow board. Unfortunatley, I cannot open the slides on my RV to access the fridge easily. It is parked on the side of my house with very little space. I will have to wait for a day when I can pull the RV out and put it on the street. Maybe tomorrow, but most likely Saturday.

    Does anybody have any troubleshooting tips for the eyebrow board? I have some voltage measurements earlier in this thread, but I am not sure what it all means.

    Thanks!

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