How to swap out the thermistor in your Dometic CFX

[emyers]

I'm experiencing similar issues with my CFX65. It first showed ERR2 when turned on which is a NTC short. The screen read 122 degrees which of course was wrong. It works fine otherwise though, will cool it off, but just runs forever because of the thermistor readout. I spoke to dometic CS which wasn't very helpful so I ordered the Ebay part from OP that is 7 degrees off, haven't yet received it. Just wondering if anyone else also saw ERR2 or extremely high temp readout with their fridges? Thanks

 

[Bravo30]

I was getting an Err2 code so I replaced the thermostat and everything works fine now. I also cleaned the aluminum fins in there while I was at it.

When I first called Dometic they said they couldn’t trouble shoot anything and that I would have to take it to service center where their tech would look at it and then call Dometic and talk to their tech but that’s only for warranty work. Non warranty work I was on my own. We called back a 2nd time and a different lady sent us out a thermostat for FREE! Here’s the part number or what’s left of it after my dog tore it up ?
Be careful buying off of Amazon and eBay, lots of fakes out there.

 

[SBSYNCRO]

Great to see all the additional info - thanks all for contributing to this thread!


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[mep1811]

If you're having problems with temperature control, you probably have a bad thermistor. Apparently they are a weak link on Dometic fridges and have been for many years. Some last 10+ years; mine lasted about 4 before it crapped out.

Luckily the CFX fridges require a lot less invasive surgery in order to replace the thermistor than the earlier models. Unfortunately I was busy doing the work and figuring things out, so my pictures aren't great, but they will give you a basic idea of what to do.

My fridge started freezing foods solid, despite being set to 40º (and showing 40º on the display). The actual interior temp ended up something more like 15º. The thermistor sits against the side of the fridge compartment and reads the temp of the interior metal liner (not the compartment itself). So it will always read colder than the compartment by a couple of degrees.

The thermistor is accessed from the area where the compressor is located. Here are the steps:

1. Turn your CFX fridge upside down with the control panel facing you

2. Remove the three tiny screws on each side panel and the 8 tiny screws on the bottom of only the end piece. Do not remove the Torx head screws that hold on the corner bumpers - (they don't hold the plastic cover onto the body)
View attachment 674545

3. Gently pull the lower end panel up and toward you (standing at the end of the CFX). be careful because the control wires will be connected and there will be just enough room to lower the panel to get access to the control board

View attachment 674550

4. Remove the 2 screws holding the black plastic cover to the control board and expose the control board - note the orientation of the bundle of wires under the control board - you'll want to be able to stuff them under there again without stressing anything.

View attachment 674547

5. Locate the thermistor connection (two pins, both wires will be black) and remove from the control board.

6. Locate the other end of the thermistor where it goes into the side of the box, remove the two screws holding the wire clamps, and gently remove the black mastic holding the thermistor in place

View attachment 674548

7. Pull out the old thermistor, removing the plastic cable clamps and setting them aside. Wipe up any of the thermal paste on the old thermistor and save it if you can.

8. Using the old thermistor as a guide, fish the new thermistor in under the compressor, goop your saved paste onto it, and then insert it deeply into the hole. Then mush the mastic back over it to keep it in place. Attach the two cable clamps to secure it.

9. Plug the new thermistor into the control board, being careful to orient the wires so that they will coil up nice and flat

10. Ensuring that they are flat and not causing stress against the control board when you replace it, lay the bundle of wires under the control board, then use the two screws to attach the control board to the standoffs.

11. using the remaining two screws, attach the black cover to the other two standoffs, securing both the cover and the control board with the wires underneath.

12. Reattach the cover by inserting it all along the bottom edge where it fits into the case, then bring it up over the two round feet on the bottom of the fridge.

13. Replace the 8 screws on the bottom

14. Replace the 3 screws on each side fo the case.

Test the operation by setting the temp to 40º and then place a cup of water in the fridge overnight. Set the cup of water on a small piece of wood so that it is not in direct contact with the side or bottom of the fridge. Test the temp of the water the next morning. It will probably be a few degrees colder than the control panel indicates - so set your temps accordingly.

Nice write up. What side did you open up ? Thanks

 

[SBSYNCRO]

Nice write up. What side did you open up ? Thanks

Thanks. It’s the side with the vents - that’s where everything is located. If you have a different model it may look different but it’s all fairly easy to figure out, I’d imagine.


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[mep1811]

I thought just one side vent came off rather than the entire section. I just replaced my thermister and it was a easy job. Thanks for the write up.

 

[SBSYNCRO]

It really is frustrating how mad Dometic’s service seems to be. I have probably told 4 other people to buy something else solely because of the lack of after-care that Dometic provides. I love my Dometic fridge but they simply are not set up to support users in North America. Perhaps that will change with the number of these fridges tHat REI seems to sell…


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[Luciano Foglia]

Hi there, I wanted to ask if anyone knows the value of the NTC resistance in the thermistor. I'm in Kyrgyzstan, impossible to find any parts over here.
I having the same issue as anyone else with the thermistor. This is a normal thermistor waterproof, If I can know the value of resistance then it will be easier for me to make the repair. These Dometic thermistors are way too expensive and in Europe they are out of stock if I get someone to send it to me.
If anyone has one around to measure it or knows the value I would appreciate some help
Best. Luciano

https://nowforwildlife.org/

 

[CLARKHOGAN]

Dometic CFX95 in a '20 jeep gladiator rubi in the bed (under a cap).

I was chasing my tail for months on what I thought were bad thermistors, failing compressor, bad logic board or anything really. Have a dedicated low gauge power line running from battery system to the bed. Odd symptoms, funky behavior, sometimes cold sometimes not, freezing my milk while melting my ice cream out on the campsite (how did we ever survive), the disturbing concerning "compressor system faulty" error after my warranty has expired. Replaced the thermistors. Still no joy. Considered going to a repair dealer or short circuiting somehow the dometic on board battery protection systems. (both batteries in the truck were replaced 4 months ago.)

Facepalm, most modern vehicles run the "house power" off of the stop start battery. Which runs substantially less amperage than the main battery. There is an intelligent battery sensor under the ground terminal on the main battery which disconnects it most of the time. So even if you have your fancy fridge hooked up to the hot big battery terminal and well grounded to the frame or the big battery negative, its not drawing that battery, its drawing the small start stop battery. Which is not enough to even maintain the fridge at cool temps. Which is obvious to me now but didn't think about it before. Which also means I need to rewire the winch.

Turns out Dometic makes a damn fine fridge after all these months of cursing.

 

[Pilotamis]

Does anyone know if these thermistors are legit or a fake? I've never purchased anything from them but at this price I'll give them a try.

Dometic 4450001983 Ntc Thermistor Asm, Cfx, Cc40 - RV Parts Express - Specialty RV Parts Retailer

Dometic 4450001983 NTC Thermistor ASM, CFX, CC40

rvpartsexpress.com

 

[Etoimos]

Does anyone know if these thermistors are legit or a fake? I've never purchased anything from them but at this price I'll give them a try.

Dometic 4450001983 Ntc Thermistor Asm, Cfx, Cc40 - RV Parts Express - Specialty RV Parts Retailer

Dometic 4450001983 NTC Thermistor ASM, CFX, CC40

rvpartsexpress.com

I just order a thermistor from them about 5 minutes ago. The part was $7.99, but the shipping was just under $17. Before I ordered it I did call Dometic customer service and a very nice lady confirmed what my issue was and gave me the part number. I could have bought it from Dometic for $5.99, but their shipping was more.

Edit: I got a shipping notice from them 20 mins later.

 

[HWY395ghost]

I just order a thermistor from them about 5 minutes ago. The part was $7.99, but the shipping was just under $17. Before I ordered it I did call Dometic customer service and a very nice lady confirmed what my issue was and gave me the part number. I could have bought it from Dometic for $5.99, but their shipping was more.

Edit: I got a shipping notice from them 20 mins later.

Same thermistor for all Dometic CFX units, even the IM model?

 

[Etoimos]

Same thermistor for all Dometic CFX units, even the IM model?

Sorry, that I do not know. I ordered it for a CFX 65W. Call Dometic customer service to see if that will work for your IM, they were very helpful.