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 > Dometic RM46E 3-way RV Refrigerator Over Cooling

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bentSpaceTime

Reno, NV

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Posted: 02/10/18 02:31pm Link  |  Quote  |  Print  |  Notify Moderator

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.

GordonThree

Northern Michigan

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Posted: 02/10/18 02:35pm Link  |  Quote  |  Print  |  Notify Moderator

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

Is replacing not in the cards?


2013 KZ Sportsmen Classic 200, 20 ft TT
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dougrainer

Carrolton, Texas

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Posted: 02/10/18 02:53pm Link  |  Quote  |  Print  |  Notify Moderator

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

bentSpaceTime

Reno, NV

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Posted: 02/10/18 04:20pm Link  |  Quote  |  Print  |  Notify Moderator

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.

bentSpaceTime

Reno, NV

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Posted: 02/10/18 04:21pm Link  |  Quote  |  Print  |  Notify Moderator

Would replacing the thermostat fix the problem, if the bypass flame is too big?

bentSpaceTime

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Posted: 02/10/18 04:55pm Link  |  Quote  |  Print  |  Notify Moderator

It looks like it does have two thermostats, one for the gas and one for the 120 electric. Each has its own capillary tube.

bentSpaceTime

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Posted: 02/10/18 04:56pm Link  |  Quote  |  Print  |  Notify Moderator

Going to test it on 120 and see what happens.

dougrainer

Carrolton, Texas

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Posted: 02/10/18 05:11pm Link  |  Quote  |  Print  |  Notify Moderator

bentSpaceTime wrote:

Would replacing the thermostat fix the problem, if the bypass flame is too big?


Yes, I found a few listings for the Gas Tstat. NONE for the electric tstat. So, if the Gas is defective, maybe one of the suppliers still has the gas tstat (pn 62303). Doug

bentSpaceTime

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Posted: 02/10/18 06:27pm Link  |  Quote  |  Print  |  Notify Moderator

dougrainer wrote:



Yes, I found a few listings for the Gas Tstat. NONE for the electric tstat. So, if the Gas is defective, maybe one of the suppliers still has the gas tstat (pn 62303). Doug


Awesome! Thank you! Where did you see it listed?

Chris Bryant

Arden, North Carolina

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Posted: 02/11/18 04:42am Link  |  Quote  |  Print  |  Notify Moderator

Because the thermostat is modulating the flame, I doubt it has lost its charge, unless it only modulates at the very bottom of its range.
Have you checked the lip pressure? I would sure start with that.
I'm pretty sure I have several of those v35 thermostats, if I can find them.


-- Chris Bryant
My RV Service Blog
The RV.net Blog

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