Where to find replacement thermistor for old RV refrigerator

Hi, Dave, 
I have the ubiquitous Dometic 2454RM in my 2013 Casita. It is original with the camper. I know that these units are notoriously slow to cool down. Over time, my unit began to take 2 to 4 days to begin cooling. I don’t even know enough about refrigerators to be dangerous, but since the unit is elderly, I thought I would look “under the hood” myself.

The first thing I noticed was the cooling fan had seized. That was an easy fix. I then tested the thermistor and determined it was bad. I shorted the tabs on the thermistor and the refrigerator began cooling very effectively. This is not a long-term solution, of course, because my fridge could turn into a freezer. The thermistor has a range of F40 – 15C.

And, finally, here is my issue. I have searched the internet (including the Dometic website) and am unable to find an exact replacement. My question: How critical is it that I replace the thermistor with one of the exact specifications? I did find a replacement on eBay, but the price was $95 and it had sold, anyway. From what I have gathered, i would believe the cost would be in the range of $6 to $8. Thanks so much for your help! —Joseph, 2013 Casita 17SD

Hi, Joseph,
It took a while to get a response from my Dometic contact, as most RV contacts take the last part of December and first week of January off. RV shows kick in after that and they are on the road constantly.

Testing the thermistor

Just to help bring other readers up to speed, I assume you tested the thermistor with an ohm reading. Typically, the procedure is to remove the thermistor from the evaporator coils inside the refrigerator and place it in a cup of ice water. This brings the temperature of the thermistor close to freezing point. Then use an ohm meter on the ends to determine resistance.

Your owner’s manual should have a chart showing the temperature and the resistance, similar to this one. Here we see at 32°F, the resistance reading should be between 30.0 and 32.0.

You also verified the thermistor was not working by bypassing it. You are correct that this is not a permanent fix as you would have an icebox rather than a refrigerator and freezer.

Here is what I got from my Dometic contact: “Nearly all of the Dometic absorption fridges use the same style thermistor. They just have different part numbers for the different lengths needed for the different size fridges. These are still available from us. They just might end up with one slightly longer than the original.”

Current part number: 38510590422

According to my Google search, they are all over the place—from eBay to Panther RV Products. Panther RV is a trusted RV parts distributor and one I would recommend using.

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Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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