My air-con has worked great for the 11 years I've owned the truck. I've had it re-charged about 8 years ago. Last week it started playing up. It'll work as normal for ten minutes and then stop working, just putting out ambient air. I paid £85 ($150) to have it re-charged today with new valves and a catalist to run on 143 ref.. and it's still the same! After 10 mins it stops drawing the clutch in on the compressor. Anyone point me in the right direction?