Fan has nothing to do with the effectiveness of the cold inside the cabin. The fan will kick in and out as it seems fit. This could be several factors, check pollen filter, heater control panel. When they regard the system did they check for leaks? The better systems vacuum the system to ensure it will hold the gas. Leaking refrigerant into the atmosphere isn't great.
“Racing is life. Anything before or after is just waiting.” – Steve McQueen