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FIXED Sub Zero 427R fridge drawers not cooling


Premium Member
Jan 19, 2023
Model Number
More than 10 years
I have a sub zero 427R wine storage / fridge. The fridge drawers have stopped cooling. Repair tech determined on first visit that it was either the control panel (on top drawer) or the control board that needed replaced. On second visit he came with parts and determined that it was the control panel that need replaced. But, big but, the part is no longer available. Based on my model and serial number I need part 4203290. This is no longer available from sub zero. Newer versions of the 427R have a redesigned control board, but they are not compatible with my specific unit. I telephoned sub zero, got a customer advocate and they confirmed that there is no replacement part available and that my unit cannot be repaired.

So I'm about to take matters into my own hands. I have a BSc in electronic engineering and quite comfortable working with electronic circuit boards. It could be a simple as a faulty relay that I could replace. I have removed the board and am ready to try and run some tests, like whether the relays are functioning or not. I'm looking for hints in what to look for.

Serial number is F2335101.


Here's the whole story... returned from vacation to find that the fridge drawers had switched themselves off -- opening drawers and no lights, LCD display off, not cold. The wine section was fine, still operating. I switched it back on and it all worked, started cooling again. Then one day two weeks later I opened the drawer to discover that it had switched itself off again. I turned it on and it started working. Two weeks later it did the same, which was when I called in for service. Service did not come for ~3 weeks and in that intervening time the drawers switched themselves off again, only this time turning it back on did not start cooling. I think however that the lights did turn on when opening the drawers. But compressor would not run. Service tech states that he ran diagnostics on the control panel in the drawer top and it checks out as okay. Also states that no power is getting to compressor. Hence he determined that new control board required -- which is No Longer Available.

First service visit...

Second service visit...
Every time I've run into the unit just shutting down, 400,600 or 700 series, it has always been the control panel or cable from it. Did you see him verify the control panel, if so how. Also a 4201991 for a 700TR looks identicle to your pic of the board.
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I did not observe him test the control panel, he just stated that he ran diagnostics. I agree, the photo of the 4201991 on CAP website looks identical to my part (except for the plastic mount, which has wider border on the top, but I don't care about that). If I'm going to order parts I might as well order the control panel and cable at the same time. Looks like the cable part was 3022950 but has been replaced with 7016027. The control panel part is either 4161550 or 4203380 depending on serial number, but I cannot find either of those at CAP. Do you know what part number I should search for?

If by CAP you're talking about Certified they're website rarely gives the updated part #'s. The panel is 7016693 and is $$$$. I would test yours first.
Thank you for your help. I have decided to order the 4201991 control board. It makes sense that a 700TR board would be same as 427R, they look like essentially the same product except one is designed to hold wine in the upper cabinet. If that doesn't fix it then I'll move on to cable and panel. Anything with the words sub-zero on it is going to be $$$$, no escaping that. I'll post back here how I get on.
Well, UPS delivered the 4201991 part this morning, less than 24 hours from when I ordered! We have progress but still issues.... the control display now shows communications error E0 and none of the buttons do anything, can't get into diagnostic mode either. However the unit is cooling, I put a thermometer in the drawer and it is down to 57 degrees (from ambient 70) in 10-15 minutes. Looking at the two control boards I do notice that the label on the CPU has different SUB# the old one is labeled 3015390 while the one I just received is labeled 3014290. So it's possible that there is different programming inside the CPU. I have checked the connection at the rear of the top drawer, I think I have it fully plugged in, but it was quite difficult to plug in.

I may be back to my original plan of trying to replace the relays on the old board I have.
Must be very careful with that cable. You seem to have access to a manual. True? This board is for a 700TR thus the difference. When you powered up were there -- in the display?
I found the service manual here.

I can't say what the display shows on initial power-up... the circuit breaker is the basement so by the time I get back to the unit it has initialized. Even though the control panel shows E0 other functions are working... drawer open alarm, lights, and we're now down to 40 degrees so I assume it is going to cool to the factory preset (which I think is 38 degrees).
Since you're putting a board for a 700TR all ref into a 427R combo see if you can reconfig. Open bottom drawer, then press colder & unit on off and release, then press bell & unit on off and release. See what model code shows up if this works.
The unit is cooling to factory default (my thermometer read just under 37 degrees) and then shutting off, so it does look to be regulating the temperature. I was able to monitor the display during initialization, it starts by immediately displaying E3 on the left side of the display, a fraction of a second before the lights come on. After 30 seconds E3 goes away and E0 is displayed on the right side of the display. Trying cooler + unit on/off and release does nothing, nor does doing that and then bell + unit on/off and release. None of the buttons respond.

I tested the relays on the old board and they seem to be just fine. I put the old board back in but it is completely dead... no lights, nothing. But a fan seems to run. So the old board is definitely dead, so I put the new one back.

Maybe one of the newer control panels would be compatible with the board I have, but that would probably be trial-and-error.

The new board is at least cooling and while I can't set a specific temperature we will just have to live with it. There are no good alternatives, sub-zero no longer makes a unit that will fit into the custom-built cabinet that we have. I would have to rip out the cabinet and have new one built for either a 24" wide or 30" wide unit, and 84" high. Sub-zero offered me a $1500 rebate if I bought one of them, but I don't think it is worth it. Searching the internet I do see other manufacturers with 24" wide that would fit into the space I have, not "built in" but would fit. As I said, no good solution.

Thanks for your help. I at least have the drawers cooling again.
On the 400-2 series the panel has to be configured when the board is replaced. Yours is not a -2 series but the panel is the same. It was worth the try but if you cannot get into the config mode I guess that's it.

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