DOMETIC RMD8551 ~ Need help1

[Ken Abel]

My Dometic absorption refrigerator RMD8551 recently developed a problem after returning from a trip that it would not turn off.

The last power source it ran on was 12 volt fed from the caravan battery & vehicle when travelling.

I turned it off the usual way on the control panel & proceeded to clean it inside when it turned itself back onto 12 volt , which was the last energy source it ran on.

I turned it off again & 10 seconds later it turned itself back on .I switched it to mains power (240 volt) to see if I could trick it).

However it switched  back on again even with repeated attempts at turning it off.

The button switch on the control panel seems to be working ok as after pressing it the refrigerator  shuts off for 10 seconds then restarts.

I removed the wiring harness from the PCB & re-seated it , no improvement.  The Dometic tech guy suggested  changing the PCB , at $380 it would be an expensive guess with no guarantee of it fixing the problem.

I have been removing the fuse from the control circuit temporarily to shut it down till I can solve the problem.

The refrigerator still works ok on the cooling side with all 3 power sources.

Has anyone got any ideas?

Cheers Ken. 

[Kirk W]

You didn't say where you are located, but the model that you show is not sold in the US or Canada so I'm guessing that you are in either UK or Australia?

In researching, I did locate a copy of the Owner's Manual and also a copy of the Dometic Service manual and you can download a copy of each. I have worked on a lot of Dometic refrigerators over the years, but only US models so my knowledge is pretty limited. I did locate a copy of the schematic on page 19 of the service manual and the same one on page 20 of the owner/installation manual. Since they are the same and it appears that the on/off switch you have and all control functions are located on that one circuit board. All control functions are powered by 12V, direct current so removing that supply would disable all functions of the refrigerator. Starting on page 30 of the service manual there is a process to enter a diagnostic mode and test various components, but I found no way to test the on/off switch. If you have a multimeter you should be able to do that using the ohm scale. Beyond that, all that I can suggest is trying the circuit board as your Dometic tech guy suggested.

[Ken Abel]

16 hours ago, Kirk W said:

You didn't say where you are located, but the model that you show is not sold in the US or Canada so I'm guessing that you are in either UK or Australia?

In researching, I did locate a copy of the Owner's Manual and also a copy of the Dometic Service manual and you can download a copy of each. I have worked on a lot of Dometic refrigerators over the years, but only US models so my knowledge is pretty limited. I did locate a copy of the schematic on page 19 of the service manual and the same one on page 20 of the owner/installation manual. Since they are the same and it appears that the on/off switch you have and all control functions are located on that one circuit board. All control functions are powered by 12V, direct current so removing that supply would disable all functions of the refrigerator. Starting on page 30 of the service manual there is a process to enter a diagnostic mode and test various components, but I found no way to test the on/off switch. If you have a multimeter you should be able to do that using the ohm scale. Beyond that, all that I can suggest is trying the circuit board as your Dometic tech guy suggested.

Hi,  yes I am in Australia.  Thanks for the prompt reply Kirk.

The service manual link that you sent has been helpfull with other controls that I didn't know about.

As for the unit switching itself back on at random, the problem seems to have corrected  itself. It is working perfectly now.

Maybe charging the vans batteries did the trick?

Cheers, Ken

[Kirk W]

6 minutes ago, Ken Abel said:

Maybe charging the vans batteries did the trick?

While I wouldn't think that was the cause, it may be possible, depending upon how the circuit is designed and without seeing more information about the control circuit board than they share it is impossible to be certain. I think that I'd just keep a close eye on things and see what happens.