I read an article in the motoring press a few weeks back which suggested that A/C systems can lose 10% of their gas every year.
Mine had not been done in 5 years so I took it to a local firm (Halfords for those in the UK) who checked and found it was right on the minimum limit on their test guage (they put a guage on the low pressure side and run the system at its lowest temp) charged me £50 in all to check and regas it (gas was £40). Took about ten minutes. You can do it yourself very easily too with the parts they sell (gas cylinder plus guage and valves) System works much better now.
