I have a 642/0 side by side sub zero. Although

If the refrigerator compressor runs and cools when you use the manual activation mode but does not run normally then the control board would be what I would suspect. If it has the manual activation then it is new enough to give error codes. If it is not running and not recognizing it's not running, something is wrong with the control. Unless you are seeing two dashes in the refr display. That would mean the refr section was disabled.

A picture would be helpful, but there should be two 2 digit numbers. the one on the top should be fridge temp reading somewhere around 34-40, and the bottom one should be freezer temp, reading around -2 to 05.

Sub-Zero a hallowed name in refrigeration, and the 642 side-by-side refrigerator/freezer unit is a landmark Yeah, it's that impressive. Dual refrigeration uses two compressors and three evaporators, I can tell you to never expect less than $300 for calling anyone to your home!

Ideal temp is 34-38 degrees, the vacuum light means the unit needs to be cleaned around the condenser area.

I’m happy to help further over the phone at https://www.6ya.com/expert/gere_bf68e6055dd61249

ck the cond coil and if dirty cclean it and make sure the fan on the coil is workiign / if this does not correct problem change the tempt control .. mm .. do the general mantaince first then look for the tuff stuff. mm

it's condensate from the evaporator coils. when the humidity collects on the coils, it should drain into a pan under the fridge that gets evaporated from the hot-side line. check to see if the condensate tube from the coils is still in the pan.

check the condencer on top .open the doors look up you should see three screws take them out and pull down the panel and clean the condencer if its clean CALL repair guy!

There is a tiny set screw that holds that in place. It is on the bottom of the stand off and just needs to be tightened.

I assume you have the long stainless handle. If so there is a tiny set screw on the stand off. It is on the floor side and just needs to be tightened.

Just posted this elsewhere and it sounds like the same problem:
As you probably know, the recommended temperature range is between 35-45 F so if your control will not allow you to set this, the sensor or associated regulator has failed. 

This seems to be an issue with Sub-Zero.