W124 E320 Coupe Compressor not working

[Philmac]

Had Compressor replaced on the advice of aircon workshop (new) due to no A/C and regassed.

Now find compressor not engaging no charge, so my guess is electrical fault. Checked fuses appears to be OK. Before i spend more big bucks can someone advise best route to follow re the most likely suspects. As you can imagine I am completely underwhelmed with my local aircon workshop.

 

[BlackC55]

Is is a genuine system or a Diavia one?

 

[aircondoc]

If it still has gas I would suspect pressure switch, or perhaps they haven't connected the compressor electrics. If pressure switch is duff it is telling the system there's no gas and wont allow the compressor to run. Compressor electrics is just a 12v supply to a coil to turn it into an electro-magnet and turn the comp. I'd go back and challenge their work, why didn't they check it before giving the car back?