2001 Pontiac Montana Van

When the summer heat starts and freon seems a little low, I start to add some freon and the system looses its slightly cool air and blows warm air. Last week, I tried to add a can and the system started to blow warm air. I took the van to a local repair shop and asked to vacuum the system and recharge with 2.2 lbs of 134a. That afternoon the mechanic called me and said it was still blowing warm air. The last two years, I woud vacuum down, recharge and the air would blow cold for the rest of the year. Any suggestion as to what happens when I try to add to the low system, it blows warm air? Also, which relays operate the aux. fan. The one on the left, standing in front looking at the motor. That fan doesn't seem to work.

What were the pressures at when they added r134a? High side and low side. There may be a restriction in a high side line before it gets to the oriface causing the refrigerant to "lose its cool" before it should. Does the compressor cycle properly? What's the temp at the drivers and passengers side of the condensor? Any lines sweating?

Changed the compressor and everything was ok.:runaround: