air con stopped working

Hi all

last year i had a 2nd hand air con compressor fitted and a regas done. system worked fine all summer/winter/spring but after 2 week sitting not moving while i was on holiday i doesn’t work any more. When the car is hot inside the temp of the air from the vents when I switch from auto to econ seems to get slightly colder! Anybody know what numbers I should expect from the diagnostic mode of the climatronic system and can I tell if the compressor is working or is it a sensor problem/ flap problem without dismantling the car.:(

Thanks

Andy