Originally Posted by Mike
1 word. Money.
They can make more by selling an expensive part and an expensive service. Its actually easier labor wise/time wise to replace the compressor than it is to replace the clutch. The mechanic can actually work 2 different cars just while yours is pulling a vacuum, then recharging.
Actually it'* much easier to replace the clutch. Take the tire off, untighten the belt, unbolt a screw, take two clamps out, and replace the clutch. No need to unscrew the lines, vacuum, refill etc..