That statement is very vague. The AC doesn't work....

1)Does that mean blower works but not cold?

This could mean low charge. If really a low charge, then the pressure switch has shut down the compressor to avoid damage)
Or could mean inoperating climate control unit. (the push button unit has bad relays)
Or your air sampling blower motor is bad.(located in the passenger knee bolster.
Or the roof sensor is bad/dirty/unplugged.

2)Blower does not work at all.
This could be blown fuse or bad strip fuse.
Or bad blower motor.

This is a complex system. So start with the fuse. Then remove the strip fuse. Clean the contacts, clean the screws. Put a slight bend in the strip fuse before reinstalling.
Test the air sampler blower motor. With car running tear a small piece of paper and place over the roof sensor. If the sampler blower motor is working, the paper should stay put.
If the paper falls, remove the air sampler blower motor.(On W126 it's located in the passenger knee bolster)(On W201 it's just beneath the passenger AC vent. Clean and test or replace.

To clean the roof sensor,remove the front dome light and pop out the roof sensor. Blow the dirt from the sensor.
Check to see if the compressor engages when you punch the AC button in on the dash.
If it engages, clean the sight glass and take a look. Lots and lots of bubbles? Need a recharge. Some bubbles but mostly clear? Probably do not need a charge.

If you push the AC button and nothing happens. Then there is a relay/electrical issue. If fuses ok then you have a very low charged system. Presure switch will keep system shut down. Or if no blower, the blower motor is bad.

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