Volvo Repair: air condition, trip to florida, air condition

Question
I purchased a used 2000 V70XC AWDSE Volvo (90000 miles) and shortly thereafter I discovered some problems with cold air. I noticed that when I was driving in the town or "stop and go" on the highway, the cold air would stop blowing. Originally I thought maybe the cooling gas has escaped. I took the car to the garage and they added some cooling gas. However, since it was already a fall I did not use the air condition until my recent trip to Florida. On that trip I discovered that when I drive on the highway with a constant speed (normal deceleration and acceleration) my air was working fine, however, as soon as I entered a city and went on the streets and begun slowing down and stopping my air condition would stop blowing cold air. After returning on the highway, and after manually switching my air off for a minute, and turning it on, the cold air would start blowing. The mechanic I talked to wanted me to replace the entire system but I do not believe that is the real cause. Could you help me? Thanks
Wes

Answer
Wes, Mechanic that wanted to replace the entire system?  He must be looking for a huge ticket.  What I have seen on these is the clutch on the compressor needs to be reshimmed.  If you are in Florida now, depending where you are, I can take a look for you.  Roger