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RayZen's avatar
RayZen
Explorer
Oct 12, 2017

Need Advice About Replacing an RV Fridge Thermostat

While replacing the cooling unity on my old Dometic RM663 refrigerator, I accidentally broke the capillary tube. One step forward, one step back.

So I have a couple of questions:

1) Does anyone have a good recommendation as to where I can buy a new one?

2) Any tips on replacing it? (e.g., do I need to keep the capillary tube away from any surfaces? Is the length of the attached capillary tube critical. On the old one, the capillary tube excess was coiled into several coils, so I doubt that it matters, as long as it reached the back of the fridge's food compartment, of course.

3) I have looked & looked online, but can't find an exact match for the thermostat's model no. (Ranco K50 P1257), so is there a cross reference somewhere that I can use to find a substitute?

Any help would be greatly appreciated.
  • trailrider:Thanks for that link. I just sent an email off to Andrew in Ontario, so we'll see what he says.

    NMDriver: Yeah, that might just work. After all, the thermostat is just a temperature-controlled switch, so I guess the underlying mechanism shouldn't matter. I suppose the old thermostat's capillary tube probably had gas in it; dunno. But I would much rather have only a wire going from the front panel thermostat switch up to the back of the fridge than another fragile capillary tube that is susceptible to being broken like the old one. If anyone else has any thoughts on this, please chime in!
  • As a last resort if you cannot find the correct part: I used a regular refrigerator thermostat and control knob. I just spliced it into the wires and control unit on my Dometic and it has worked fine for 6-7 yrs now.

    I think it is a freezer thermostat and not the lower unit thermostat but it works so I have not tried to switch it out for a different unit. The only issue I have is on the dial it will freeze the top shelf at the 3 setting and the whole frig becomes a freezer if it is turned up to 5 on a 1-9 scale.
  • If this is a mercury-based bulb and capillary tube setup, a replacement may very well not be available anywhere due to environmental regulations. Possibly there would be a suitable replacement thermostat setup that uses some other sensing technique, or maybe even one could be constructed with a little work.