For a Sub-Zero 511:

The compressors (both) are very hot and seem to run a lot. The freezer and fridge cool fine. I heard condenser fan noise last night.

I am guessing that the condenser fan is starting to fail and that allows to compressors to get too hot.

Does that make any sense?

I am assuming I should replace the condenser fan and then they compressors will run cooler and maybe turn off once in a while.

Please advise.

JonV

I assume you have already done the obvious and cleaned out any dust and debris build up from the condenser coils. And nothing is blocking airflow.

Refrigerators or freezers should never NEED to be turned off... except when defrosting might be required.

Yes, the coils are clean.

Why the comment about "never NEED to be turned off" ?

What does that have to do with my post?

All has to do with how you read what you posted...

Does that particular model have ports where you can check refridgerant pressures? Or is it permanently sealed like most other cheaper ones are?

Low Pressures will result in longer cycle run times as well, which will in turn cause it to run far hotter and accelerate wear and a failure.

Fans generally run or they don't... and if they are running slowly or noisily you should be able to see. If you turn it off and spin the fans by hand... are they tight? Or have loose shaft bearings?

A failing condenser fan will cause it to run hot, but bad valves in the compressor will do the same thing. Make sure the cover is on the rear of the refrigerator because if it's off the airflow will not be over the coils like it's supposed to be.