What can suddenly cause my air conditioning to stop cooling? on 2007 Mercedes-Benz ML350 4MATIC

I drove my car out for a meeting in perfectly good condition.
After the meeting, I started the car and the Air conditioning came on as fan but the compressor to cause cooling did not come on.

Asked by for the 2007 Mercedes-Benz ML350 4MATIC
1 answer
seek diag from good a/c tech