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I have a Subzero about 9 years old. I am getting a vaccum

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I have a Subzero about 9 years old.   I am getting a "vaccum condenser" once a day and it seems that lately the condenser is running too much. I power cycle the fridge to cut off the condenser and it stays off for half an hour or so (when I have been able to time it). The setting is at 40 and the thermometer that I have in the fridge is usually somewhere between 32-35--but when I am seeing these temps, the condenser is still running. What is the chance that I have a sensor failure and need a new electronics board? Could an electrical storm, with a nearby lightining strike taken some of the electrical components out? When a problem like this occured many years ago the tech claimed it was a freon leak, but replacing freon did not necessarily cure the problem. Thanks for any help you can provide.
With the ref compressor running, open the ref door and leave it open. Using one finger to hold the ref "Colder" button, briefly touch the "On/Off" button and release both buttons. Pressing the "Colder" button will cycle you through the thermistor readings, I forget which order they are in but it will tell you freezer compartment (around 0), freezer evap (around -10), ref compartment (around 34-40) and ref evaporator. That will be the key value. It should start at around 35 and drop down to 20 with the door open in about 5 minutes. You will have to repeat the button pressing after time. If the coldest the ref gets to is around 30 or higher you will need to have the ref evaporator replaced and the system evacuated and recharged by a certified refrigerant technician. If you use a Sub-Zero authorized company the parts are still covered by warranty.
Customer: replied 9 years ago.
I sent a reply to the email I recieved with more details on my question. I am not sure if that is the proper way to continue the discussion or if I need to comment here. Please see email response or indicate how I communicate back.
Please post all responses here. I cannot see any emails or responses from you. What did you find?
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Customer: replied 9 years ago.

OK, sorry, I am still trying to figure out how this website works.


I tried what you said and the temperature for the evaporator bottomed out at 25 then started climbing again. It did not get down to 20. What are the chances that the sensor in the feedback loop that tells the compressor when to turn off is bad. (I bought the schematics years ago when this started occurring). I seem to recall that the problem showed up after an electrical storm. I know that freon is the easy answer but....Would it be worth it to install a new electronics panel? On the freon side is it possible to have a small leak that is 5 years in the making until it makes itself felt?


Any other ideas? I will go ahead and accept the answer so you can get paid, but I would appreciate any other troubleshooting tips. Thanks for your time

>>>On the freon side is it possible to have a small leak that is 5 years in the making until it makes itself felt?


Yes, absolutely, You can test the thermistors if you like. Remove the ref shelves and the light difuser. You will see three (or maybe four) screws which attach the rear panel, remove them and pull the top of the panel forward and lift the panel up and out. The thermistors have two royal blue wires about 6" long, unplug them and remove. Put the bit in a glass of mostly ice water for at least two minutes and take a resistance reading, it should be around 10,000 ohms +or- 500 ohms. The wiring harness connectors often get corroded but then the display will flash "vacuum condenser" and it will not give a temperature in diagnostic mode but will say "EE".


I really don't think a thermistor or control board is your problem. While you are testing the thermistors it will be a good opportunity to check the frost pattern on the ref evap coil. If the coil has only the top one or two segments frosted then we can be assured the problem is a refrigerant issue. If there was a leak and it was not repaired but merely refilled of course it will leak again.

Customer: replied 9 years ago.

Just wanted to let you know that the thermisters checked out, unfortunately. It would have been easier if it was an electrical problem!


I have a friend who should have a device I can use to read the pressures, but you are right in that there is probably a small leak. The trick now is to find it and not just pay (again) to get the freon recharged. Bummer!


Thanks for all of your help!

I told you. Just don't let anyone put in anything but virgin (non-recycled) R-134a refrigerant.


PS I told you so.