Dometic Cff35 - Bad Thermistor?

We recently had some operational problems with our Dometic CFF35 refrigerator (ie, freezing entire contents even though setpoint was 46F), and the internet posts all seemed to point to a failed/failing thermistor. This became more involved than I originally expected, and so I thought I would share my findings.

Is my thermistor bad: I removed the bottom venting enclosure surrounding the compressor and controls, and was able to easily get access to the thermistor 2-pin connector. It read about 11 k-ohms resistance. But I had no way of knowing if this indicated good or bad thermistor.

Replacement thermistor: Dometic website refers you to local RV dealers for replacement parts, but the 3 dealers I spoke with all reported they were unable to determine correct part. A call to Dometic customer service revealed the proper part number for thermistor for this refrigerator: 4450001983. They did not have it in stock, but I found one at rvpartsexpress.com. I measured resistance of new unit, and it matched my existing thermistor.

My solution: since existing thermistor checks out electrically, I pulled it out and saw that there wasn't complete coverage with thermal paste, so I added as much thermal paste onto the tip as I could, and re-inserted it, and closed everything back up. Running the Dometic for several hours shows it is now tracking to the setpoint properly, and I now have a spare thermistor for that day in the future when current one fails.

 

Hey moderators, how can we get this guys Newbie badge upgraded with an honorary title?!

Great post Sir! Welcome...

I have a similar post about my CF35 doing the same thing happen, although my thermistor was actually bad. When mine failed the compressor ran full speed for a couple days and the scroll compressor met its match...it was unable to reliably cool even after the electronic problem was resolved. Now, we now have a CFF35 as well.

While it was a pricy experience, I have to say the CFF35 is better in just about every way...no metal rivets inside the chest, seems to be more evenly cool throughout, more space...just a nice fridge.

 

Excellent write up Forrest! I am glad you were able to diagnose this. This will help others in the future for sure, this should be an important go-to post on the forum.

Cary