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FIXED Sub-Zero 650 refrigerator with intermittent warming of refrigerator (technician already came)

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william13

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Ok I used an infra-red (16710 TE), a fisher scientific digital, a rubbermaid refridgerator thermometer. Pretty much all are 3-4 degrees higher than the 38 degree set point. The refridgerator believes the temp is 3-4 degrees cooler than the other thermometers. The compressor kicks off when it gets down to 38 but its seems really to be 42 degrees. So it seems the brain of the fridge like it needs to be temperature calibrated or something.
 

rickgburton

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Use your laser thermometer and measure the temperature of the evaporator. The refrigerator door must be open for five minutes with the compressor running.

600 series.jpg
 

william13

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Sorry I am not sure I understand this. I should point the lazer at evaporator with door open. Should I depress the two switches light and fan when I conduct this.
Also heads up. I did get a hold of a new control board that I can replace if its not the problem.
 

rickgburton

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I should point the lazer at evaporator with door open.
Kind of hard to do with the door closed.
Should I depress the two switches light and fan
No, just open the door. If the compressor is not running wait for it to turn on (with the door open it shouldn't take that long) then wait 5 minutes
 

william13

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When I inspected the thermistor the other day I removed the back panel inside fridge and saw coils (I believe this is the evaporator). Do I need to remove shelves and back panal again or can I just aim at panel which is infront of evaporator (I think)
 

rickgburton

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saw coils (I believe this is the evaporator)
That's correct and the reason I want you to use the laser is you need a accurate measurement of just the coil and only after the compressor runs with the door open, for five minutes ie;
Door open for five minutes, compressor running for 10 minutes = No Good.
Compressor running five minutes, door open less than 5 minutes = NG.
Compressor running less than 5 minutes or more than 5 minutes =NG.
Door open less than 5 minutes or more than 5 minutes = NG
 

william13

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That's correct and the reason I want you to use the laser is you need a accurate measurement of just the coil and only after the compressor runs with the door open, for five minutes ie;
Door open for five minutes, compressor running for 10 minutes = No Good.
Compressor running five minutes, door open less than 5 minutes = NG.
Compressor running less than 5 minutes or more than 5 minutes =NG.
Door open less than 5 minutes or more than 5 minutes = NG
So if I have to remove the back panel and expose the evaporator then I will do this on the weekend. I hate emptying the refridgerator! BTW temp set at 34 and its down to 38 now. Yest it was 40! Could the final few degrees be a slower journey?

BTW as mentioned I bought a board on ebay listed as new and undamaged but when I look at the picture (upper right) it looks to these old eyes that a connect has broken tabs. Would you peak at this for me?

ebay.com/itm/NEW-SUB-ZERO-4202800-3014300-20A1468-00-Refrigerator-Main-Control-Board/265003442908?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2648
 

william13

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I don't see any broken connectors.
when I looked at P1 just to the right of P2, it looked to me like the clip of P2 was lying on the board ie the clip that secures the plug. Is it just an illusion? And in the lower left and mid area most board have a blue attachment and I did not see this: Here is another board that I compared it to:
 
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william13

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I have not done that last exercise yet because I am waiting for this weekend but I would like to run a thought by you.
Regarding the fact that my sub zero in refridgerator display reads "34" and the set point is "34" but other thermometers read 40 ie 6 degree descrepancy.....another thought comes to mind. I did test the thermistor in cold water and it reads 30,000 ohms (30-33,000) but I heard the Molex connectors can go bad adding to the resistance and making the mainboard think the thermistor is colder. So I ordered a new thermistor kit by subco which was no more than ordering butt splicing connectors separately and I intend to "butt splice" a new thermistor in just to get rid of Molex. Thoughts?
 

rickgburton

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william13

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They have these head shrink things that you crimp and heat shrink:
amazon.com/Supco-TH4150-Refrigerator-Thermistor-Replaces/dp/B00LULF5JO

found this article: appliantology.org/blogs/entry/1046-waterproofing-splices-in-refrigerators-and-freezers/

I think this is the actual butt connector: Not sure if you crimp or solder or both: amazon.com/Red-22-18-AWG-Krimpa-Seal-MonsterBolts/dp/B07NLKL7VT

What is your recommended technique?

This is the blog in which someone had a bad molex: appliantology.org/topic/62152-subzero-642-temp-readout-showing-35-fridge-actually-50/
 
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william13

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Follow up:

I replaced the refridgerator thermistor with the Supco name brand. Used the Butt splice heat shrink connectors they supplied and then wrapped it in "black tape".
Left the setpoint at 34 which normally got the fridge down to 40 degrees. This a.m. I checked the temp and it was 32 degrees in the fridge (the thermometer sits in water which froze) with the compressor still running.
So I put the setpoint back to 38 where it never worked before and now I am waiting to see where the temperature will go to. Here is the other interesting thing. I tested the old thermistor with the whole molex connector attached to it and it read 30,000 ohms right on spec so it was not the Molex. The new thermistor tested the same without the Molex. So replacing the thermistor which seemed in spec resulted in much colder fridge which confuses me.
 
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