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Thermistor Setting


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#1 Hot Toddy

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Posted 16 September 2020 - 12:30 PM

Can someone give me an idea of where the thermistor setting should be for optimum cold? There is a peel and stick arrow on the side of the fridge cabinet but should the top, middle, or bottom of the plastic clip align with that? I watched a YouTube video by an RV maintenance technician in the Pacific Northwest and he the higher up the cooling fin the colder the setting, but that seems to have the opposite affect on our fridge. This is on a Dometic fridge they install on the 17 Casitas.

Also, how often do the thermistors fail? Ours is seven years old. The cooling mechanism in the back of the fridge is hot so I know it is working, but we cant seem to get the cabinet any cooler than 50 degrees this week. Ambient temp is only 85 degrees and we are in the shade.

Thanks!

Toddy

#2 vermilye

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Posted 17 September 2020 - 04:27 AM

General information from Dometic - 

 

It should be slid to the top of the fins for the coolest temperature.  It only makes a 3°F - 4°F difference in temperature sliding between the top & bottom.



#3 Mark Watson

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Posted 18 September 2020 - 06:13 PM

I've been troubleshooting my fridge for a couple of months now. It was struggling to get down to 40 degrees. I tried things like cleaning the fins and ammonia plumbing from the outside in back of the fridge, moving the thermistor up as high as it would go  on the inside fins, and temporarily putting a room fan blowing air into the bottom outside vent. Only had limited success with getting it to cool better. I suspect my thermistor failed by having too high of a resistance for a given fridge temperature. So in a warm fridge the resistance should be low and as it cools down, the resistance increases and act like a switch ( switched to off ) to stop the cooling process. I replaced the thermistor and now have the fridge control set back to 3 and my fridge temp now reads 35 degrees. Outside ambient air temp is 90 degrees.


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Mark Watson

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#4 Meadowlark

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Posted 19 September 2020 - 05:31 PM

Where did you get the replacement thermistor? For that matter, how does it work? I haven't really examined it, but it doesn't have wires, does it?


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#5 Mark Watson

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Posted 20 September 2020 - 01:28 AM

Got if from Amazon. As the temp decreases, the resistance increases to the point it shuts off the cooling. It has two wires which plugs onto the power board, Plug location P2 I think it was. 


Mark Watson

Houston,Tx
2008 17' FD


#6 Meadowlark

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Posted 20 September 2020 - 01:04 PM

Thank you.


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#7 Hot Toddy

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Posted 21 September 2020 - 07:24 AM

I got to thinking about the last time I cleaned the gas jet on the fridge and decided that might be the problem. This morning I took it apart and blew out any debris using compressed air, then reassembled and started the fridge. I am hoping that takes care of my issue, so will keep you posted on my results. Thanks for everyone's input in helping me troubleshoot my problem.

 

Update as of 9/22/2020 - cleaning the gas jet seemed to have done the trick. Refrigerator has been running on gas all day and appears to be cooling between 36 and 39 degrees on setting #3. I have added that task to my annual maintenance regime.

 

Toddy


Edited by Hot Toddy, 22 September 2020 - 05:13 PM.