Air Conditioning Help

Hi all, you got a newbie here. I have a 2002 Saturn L200, 2.2L, manuel trans. I had my air compressor changed out and the small high side line repaired. Now my air blows super cold. My problem is that when the air is first turned on and starting/trying to get cold I get a herky/jerky feeling as if I'm in 4th gear when I should be in 3rd. Kinda like the compressor is turning on and off and straining the engine. RPMS are fine and do not fluctuate(sp). My mechanic is scratching his head and says it may take some time for the engine to get back in sink as it was tore down for 4 days while I got a used compressor for $140 instead of $680 the dealer wanted. My mechanic changed the oil in the compressor? Also it does do it less frequently now (about 150 miles) than it did at first and does not feel as bad. Hope someone can help. Thanks

:lol2: saturngirl