A/C Not Blowing Cold Air - Audi A5 2.0 TDI 2017 Sportback

Hi, 

Looking for some help please, (vehicle type in topic title) - In the first instance I went to regas my A/C, the engineer that attended mentioned the system was full and that he had carried out leak tests and confirmed no leaks were present.

However he could see from his instruments that when I switched the A/C on, the compressor wasn't switching on and that a number of things could be causing it. (He mainly only does regassing and not an actual A/C repair specialist). I did a fair abit of reading and a common issue stemmed from the high pressure switch, which I've replaced with a brand new one. I've also checked ALL the A/C fuses and they're fine too.

There are no other issues present at all, car blower works like factory, heating elements are fine etc

A/C is still blowing air at normal temperature (literally no difference in how cold the air is when the A/C is switched on compared to off). Does anyone have any ideas or come across this before? 

Thanks,

Rohit.