Don't often need cold air in blighty but was unseasonably warm last week and air con only blowing cool not cold. I'd had the system drained and recharged 2-3 years ago but with winter layups and cool ambient temps most days the air con doesn't get used.

On connecting the recharge gauge there was zero psi so proceeded to fill from the canister. Calcs with ambient temp suggest 35 psi is about right. Anyway, got to 35 with pressure holding steady - gave another squirt and there was a "whirring" sound from the front left of engine bay which I presume was the aircon pump clutch disengaging and pressure dropped to zero with engine running! Checked pressure with engine off and it was around 40psi. I let some gas out to 25 psi - restarted the engine and pressure was back up so I assume the aircon clutch had now engaged at the lower pressure. I carefully and slowly recharged to 35 psi and all is well. Having said that the aircon still doesn't blow icy cold like it does in my Eunos (Miata).

EDIT: I was being a little too cautious. Went back and repeated procedure - this time put the whole can in and pressure steady while running between 30-35 psi (outside temp today is 14*C) - now a/c blowing like a polar wind

 

Why not take it to someone with the proper machine instead of risking covering up a fault that'll be a lot more to fix if ignored....

 

Did just that at last re-charge - Kwik-fit totally drained, tested and refilled system. No leaks/issues found. Only did that as I had a "low aircon coolant" code - no error codes at all this time

 

It shouldn't need redoing so often so suspect a fault since the last time it was properly checked.