FIXED Sub-Zero UC-24BG/S/TH under counter wine cooler/refrigerator

[mjz]

Model Number

UC-24BG/S/TH

Brand

Sub-Zero

Age

More than 10 years

My sub-zero UC-24BG/S/TH stopped working completely. There is power to the outlet.
The display shows "off". When I unplug the unit and plug back in. The inside light comes on, the display reads the temperature and then I hear a click.
The light goes out and the display shows "off". If I unplug for a few seconds, the "off" disappears, plug back in, the inside light comes on and the displays shows temperature again and then I hear the click.

It seems the click is an internal shutoff/relay? I suspect the start relay has failed, but wanted to check here if that is reasonable. Part replacement is $35.00
Anyone else experience this and the fix was the relay?

 

[paulhl]

Seems like it's in Sabbath mode. Hit POWER after plugging in

 

[mjz]

Hitting "Power" after plugging in doesn't do anything. After first plugging the unit in, after a few seconds, I hear a click (from the front of the unit and the light goes out and the display shows "off". Touching the power button, holding it for 10+ seconds, etc. does nothing.

 

[paulhl]

Holding it for 10 sec is what puts it in Sabbeth, just press it and let go

 

[mjz]

Doesn't work. It's not in Sabbeth mode. Plugging in the unit leads it to light up (if door open), the display shows the temperature and then there is a click and the light goes out and the display shows "off". Pressing the power button on and letting go does nothing. The click sound may be a thermal overload, but I don't know. I was hoping someone here is familiar with this unit or the way they operate to advise on what that click sound is and what it is doing when it cuts power to the system and displays "off".

 

[paulhl]

Does yours have the tubular lights and if so is the switch on and are they lit?

 

[mjz]

Yes, I can turn the switch on and the front display light comes on. I have power to the unit (no circuit breaker issue).
The two parts I suspect are a problem is either the start relay (on the compressor) or the control box at the front of the unit.
The control box is where I hear the "click" sound. What I don't know is if the control box is "faulty" or the start relay. I doubt it is the compressor.

 

[paulhl]

Start relay has nothing to do with this issue. You're losing power in the control board. Check for 120VAC across P3 & P4. Then 12VDC across P4 and J4 pin 2

 

[mjz]

Thank you!! This is great advice. I will check the board.

 

[mjz]

I tested the voltages and there is 120 vac across P3 & P4.
And there is 12v across P4 & J4/pin 2

One of the relays is the source of the "click" (Omron G5Le-1). I disconnected the purple compressor wire (goes to the start relay), just to rule it out and the click still occurred shutting down the display & light (except showing "off" in the display).

The board itself looks brand new - no burn areas anywhere, no pop top caps or anything else obvious.

Maybe just need to replace the board?

 

[paulhl]

I agree but you might want to do a ribbon test before ordering a board. Something might be feeding back to the board

 

[mjz]

What is a "ribbon" test?

 

[paulhl]

Testing control panel outputs. If this posts the instructions are wrong. When testing for pin one for your mod # will identify pin 5.

 

[mjz]

Testing for continuity for my model - pin 3 ,4 - shows no continuity when I press the power button. And it should.
It does seem the display panel with the touch buttons is the problem. I don't have continuity with any of the buttons (warmer/colder), etc.
I can't fathom how a simple device could fail like that and yet show "data" when plugged in (i.e. temperature & "off" status)

 

[paulhl]

So you were not really able to identify pin 1

 

[mjz]

Identifying pin 1 was easy I believe. I followed the instructions and I also was able to trace it on the back since I have the display out of the unit. I can easily see the ribbon going from the warmer key to the pins. One and two were obvious. Regardless, I did check from both sides anyway (as if pin 1 were opposite and nothing I did gave me continuity.

 

[paulhl]

I've never had all traces fail. Pin 3 is obvious so I would try again 1-3 or 5-3=ref colder, should be 1-3

 

[mjz]

I'll try again, but what I think happened is not at the trace level, but at the "chip" level. The LCD display works (which is why "off" showed and the temperature showed. But the chip controlling the buttons has failed.

 

[mjz]

Problem solved. Unit is working again.
It was the ribbon as you suggested (paulhl). The replacement part came in today. I checked continuity as per the instructions and it checked out.
I installed the part, connected it, and pressed the power button and bingo. Unit started up and is now cooling down.
Thanks for your suggestion on the display.
(I'll probably have the old part refurbished and save as a spare. I have two of these units)

 

[paulhl]

Good to hear