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Sub Zero Refrigerator 550 --> Completely frozen


Premium Member
Jan 16, 2021
Model Number
More than 10 years
So this isn't good. Huge puddle on the floor and after pulling off the cover, the evaporator(?) was completely iced over. So any advice on this? The drain tube was iced up as well. It looks like there is a heating wire snaked down the drain also.

I put everything in a cooler, thawed it out overnight, then replaced the panel.

How do I stop this from happening again?

model # 550
serial # P1035377
May 1993
Obviously not going into defrost. Too late now since you defrosted it but what I do is put an amprobe over the power cord up top and turn the timer to defrost, the heater should draw 5.5 amps, if not you'll have to remove that cover again to check terminator & heater. If you get 5.5 amps(more if the lights are on) then I replace the timer. You will have to wait a few days to be sure temps are low enough. That unit comes with an aluminum strap that wraps around the heater and goes into the drain. If what you saw is braided, that's an after market drain tube heater. As far a water on the floor I've never seen water leak out of a SZ freezer, it freezes. On this model it's usually a clogged drain in the ref. section.
sooo, I'm a n00b. I found the timer in the upper access panel and CLICKED it on. several attempts and it doesn't appear 'warm' at the ceiling panel inside the freezer.

Is there a diagram or instructions for what I can touch to with the probes to measure 5.5A on the heater?

What about the drain wire? Mine's braided.

I think the water leaking out came from that mass of ice frozen to the evaporator grill. It must have been heating a little bit and dripping down the side walls and then out.
You need an amp probe to test amps. If you do not have one you need to remove that cover again along with that fan housing behind it. The connectors to the terminator (blue 120v in-grey 120v out) to a bridged connector (due to the added braided tube heater) to the defrost heater (black 120V in-white neutral) are on the right side if laying on your back. Must be below 30 degrees for terminator to be closed
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