Dometic RM46E 3-way RV Refrigerator Over Cooling

[bentSpaceTime]

My friend has a Dometic RM46E 3 way refrigerator in her trailer that over cools. It’s probably from the 70’s.

I cleaned the valve and valve seat per the manual, as it says:

“Dirt on the thermostat gas valve or seat prevents the thermostat valve from completely closing, consequently it lets through some gas when in closed position.?This condition may prevent reducing the flame to the required minimum. It will cause too low cabinet temperature. “

The cleaning didn’t seem to solve the problem though…

I tested the thermostat per the manual and it seems to be working.

“If the thermostat control assembly loses its charge, it will become inactive. To test for a lost charge, while the flame is reduced to minimum and the temperature control is set at a numbered position on its dial: Remove thermostat capillary tube from its clamp in the evaporator and warm capillary end with the hand, If the flame fails to increase in size, the thermostat has lost its charge and the thermostat must be replaced.”

There is definitely a difference between the low flame and the higher on flame.

I also tried moving the thermostat capillary tubes in the box up and down to no avail.

Last weekend as we were camping I tried playing with the gas/electric knob/valve which shuts off the gas. I turned it part way towards electric, which restricts the flow of gas a little, to were the flame became a little smaller and then the fridge seemed to operate perfectly staying between 34-38 degrees. The thermostat knob was set on 1. However by the time we got home the flame on the fridge was off and I’ve been playing with it again to try and find that balance point.

Any ideas what might be the actually problem here?

My guess is the bypass flame is too big causing it to cool when it shouldn’t be.

[bentSpaceTime]

Those things are expensive, would seem unnecessary to replace if it's still mostly working.

We actually only have used it on LP gas, so not even sure if the electric side works at all.

There is 2 capillary tubes that connect to the fins inside the box. Doesn't really look like the thermostat has ever been replaced.

[dougrainer]

You need to clarify. You should have a dual tstat.
1. On LP gas, when it senses the low temp has been met, it lowers the gas flame
2. On 120 electric, it has a contac point that opens and closes the current to the 120 element
IF it freezes on BOTH modes the tstat is defective. Taking the tstat valve apart and cleaning is never done regardless of what any manual you found and used. The Capillary sense metal tube does have a gas in it. Some of the tstats have 2 Capillary tubes, one for LP and one for 120. AND some models actually had 2 separate tstats. One for LP and one for 120, but they operated the same in bypassing in gas mode.
Have you checked to see if anybody has a replacement tstat? Doug

[GordonThree]

I'm amazed a fridge almost 50 years old is working at all.

Is replacing not in the cards?