Audi Repair: A/C problems, ac icon, refrigerant pressure

Question
my 96 A6 has the air conditioner turn off randomly when driving. even if the AC icon is on, it will turn off and only use the regular fan after driving for a few minutes. what could be the problem?

Answer
It sounds like the system is perhaps overheating or there is another reason for it tripping off.  Does the compressor stop turning also?  In that case it may be a refrigerant pressure problem, or perhaps a relay is tripping off.  The system will need to be checked for more diagnosis of the actual problem.  Let me know,  Jan