Dometic CFX50 freezing everything

SBSYNCRO

Active member
I’ve had this fridge for a couple years and it has been flawless. I set it at 39° and nothing freezes and my lithium pack will run it for 3 days no problem.

I just got back from a trip where it suddenly decided to freeze everything solid (including my beers!). After one night it drained my battery down to 20%.

I triple checked the settings - 39°. Made sure it wasn’t in “emergency mode”

Made sure all the power connections were good and normal.

I turned it off and unplugged it for a couple hours.

Then I reset it to 45° and let it run for the afternoon.

By dinner time everything g was frozen again. The temp setting was confirmed at 45° but it showed the temp as 36° (and it must have been more like 0° because my half and half was a solid cube!)

Any ideas on what to look at first to try to troubleshoot this issue?


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67cj5

Man On a Mission
You need to put a thermometer with a sensor/lead in it so you can check the real temp and adjust the fridge to suit and maybe recalibrate the LED/Dial first and once you hve worked out whats going on contact Dometic, (y)
 

SBSYNCRO

Active member
You need to put a thermometer with a sensor/lead in it so you can check the real temp and adjust the fridge to suit and maybe recalibrate the LED/Dial first and once you hve worked out whats going on contact Dometic, (y)
Yea that’s the next step but I can tell you from observation that when I set the temp to the highest possible (50°F) it freezes everything solid.

Definitely something wrong with the control board I guess…


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Had a similar issue with my ARB Zero. Read out would never show below 56f. Had a temp gauge inside and after running it on shore power over night, it was actually -22f inside. Basically it just kept running trying to meet the set point, but it thought it didn't. ARB sent me a new thermocouple and all is right with the world again.
 

SBSYNCRO

Active member
Interesting. I'm wondering if its the thermistor or the control board itself. Here's my thinking:

  1. If the thermistor were bad, it would report the wrong internal temp (usually higher than actual) and the control board would cycle the fridge until it hit the target temp.
    1. However, it would theoretically never hit the target temp (since the thermistor is bad) and so the control board would tell it to just keep running the compressor continuously. (that sounds like Hopeless Diamond's case)
    2. I've also heard that a symptom of a bad thermistor is one that reads really high - like 50ºF or 80ºF even when it is producing ice
  2. In my situation, the desired temp s set to 41º and the fridge cycles until it *thinks* the internal temp is 40º (displays that as the current temp).
    1. The fridge is cycling on and off and nearly the normal rate (about 30 seconds every 3-5 minutes).
    2. BUT the internal temp is actually 19º (as measured by a small cup of water perched in the center on a piece of 2x4)
So I have a situation where it seems like its a calibration issue and not necessarily a bad thermistor... I wonder if perhaps the thermistor could have gotten knocked loose from its mount and isn't making good contact with the metal plate of the fridge bottom... Something for me to investigate...
 

SBSYNCRO

Active member
Following up on this. After spending hours on the phone waiting, and spamming emails to every possible contact within Dometic, I finally found a SUPER helpful engineer in VA who gave me the part number for the Thermistor for the CFX50: 4450001983. A DuckDuckGo search found me a couple of retailers, but its out of stock, so now the second phase of the search continues!
 
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