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FIXED Sub-Zero 661 Freezer Compressor Always Running


Premium Member
May 7, 2023
Model Number
More than 10 years
I have a Sub-Zero 661 side-by-side. Recently I found that the freezer was getting too cold -18F. I have it set to 0F.

I got a Taylor glass-tube thermometer to verify the temp, and the thermistors appear to be accurate. They are within range for resistance as well.

I also noticed that the freezer compressor always runs. I tried turning off just the freezer (i.e. Manual Compartment Disable Mode). The LCD displayed -- (double dashes) for the freezer. But the freezer compressor continued to run, never stopping. The only way to get the freezer compressor to stopis unplug the lead from it.

I'm thinking it's a controller board issue; does that sound right? Is there a way to test the controller board? What are the other possibilities, given the extreme low temp?
The 4204380 board was back-ordered for a few weeks, but finally got here yesterday. I cut the required resistors for my 661 (many SZ models used the same board, but with different resistors cut out) then installed it. It took about an hour. The refrigerator and freezer are working perfectly now. I'm pretty happy that a $247.10 part fixed my $10k refrigerator! I wonder if it's worth sending the old board to one of those board repair shops just to keep on hand?
Last edited:
I wouldn't, like you said <$250.00 isn't bad. You know the problem, freezer run relay, if you can replace that try it.

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