Help needed with Air con please

[Phooey]

Ok guys, took car in to have air con regassed and he managed it no problem.  No keaks but he said that there was an electrical fault somewhere because the compressor wasn't kicking in.  Now he is on hols for two weeks and can't look at it till he gets back and puts his computer on it to find the faults.

Is there anything I could look at to try to identify the problem?   I want this to be sorted.

[Audi Owners Club.]

Usual fault is high pressure sensor going faulty...could try that if it comes up with fault code for it.