Dometic RM 8551 refrigerator not working on propane

[Jwwiff]

I have searched high and low across a multitude of forums for specifics on the RM 8xxx series of refrigerators and have yet to find a solution for this issue.
My RM 8551 refrigerator runs on AC, DC, but not propane. I put it into the service mode and can go through the modes and when on propane, the igniter ignites the gas and the burner burns as it should. Go back to normal mode and when switching to propane it throws the gas and fault LEDs.

1) the igniter works
2) the gas valve works
3) the GFA module works (otherwise the gas and igniter would not work in service mode) which also means that I am getting power to the GFA from the main control board on the front of the unit.

The picture attached is Dometic’s schematic between the main board (x110 connector) and the GFA. Notice that the wire labeling is different on each end. The pin out is positionally correct on the GFA connector (pin 8 empty, pin 7 is violet, 6 is black, 5 is white). I do get ~1.5VDC across 7 and 6 so I assume that the white wire on that end is the fault line. It reads ~.43V when the burner is burning (same voltage as the valves when they are opened).

Which end labeling is correct????

Also is there a set temp below which the propane will not fire? I’m at ~20F here and is there an internal temp sensor that won’t let the propane run at that temp (in which case I have been fighting this issue for the last few days….)

Thanks for any insights this group can give.

 

[CharlesinGA]

I'm looking at this manual and do not see a reference to service mode vs normal mode, can you elaborate more on this? A model number ending in 1 means that the energy selection is manual. Beyond that I see what you mean, Black is Violet, White is Black, and Violet is White, yes, confusing.

Charles

 

[John From Detroit]

I too am not familar with a "Service" mode on Dometic Refrigerators
But if you are able to get it cycle through and light.
Check to see if it lights but then shuts off when in "Operation" mode
(Stand outside and watch while a partner activates it or pull a fuse and replace so it turns on while you watch the burner)
IF IT LIGHTS. but goes out you have only a few suspects and the wire that connects them
One is the flame sensor.. a thermocouple and if there is but one wire (not counting the solenoid wires) from the mother board to the burner.. it's the spark Rod as well (if there are more wires then there should be an independent thermocouple sensor this is better)
The other suspect is of course the mother/control board.

IT's not sensing that it is HOT
NOTE: if the burner needs service it may still ight but not strong enough to heat the rod so that's suspect 3. often #1 on the list. It's the first thing I'd check
Also make sure the flu is not clogged for that will cause issues as well and may trip an over temp device depending on the precise model if clogged.

 

[Gary RV_Wizard]

Page 30 (section 5.1) of that manual describes the Service Mode of the 8551.

I'm not aware of any temp sensor in the fridge that would shut off gas flow, but at 20 F the gas pressure might get low enough to become unreliable. Usually 20 F isn't a problem, though.

The normal meaning of the Gas & Fault indicators is that the flame sensor failed to detect or report that ignition was successful. The controller reacts by shutting off the gas valve. The flame sense is a tiny voltage, so a corroded wire connection can easily defeat it.

 

[Kirk]

The normal meaning of the Gas & Fault indicators is that the flame sensor failed to detect or report that ignition was successful. The controller reacts by shutting off the gas valve. The flame sense is a tiny voltage, so a corroded wire connection can easily defeat it.

You may need to replace the ignition probe as they are known to fail as you describe if the ceramic insulator should develop a crack or similar problem.