Could be the air gap between the clutch plate and coil is great enough that the coil isn't strong enough to pull the clutch plate to engage the compressor. Turn on the AC and with the engine running give the clutch plate a little nudge. Does the compressor engage? Be careful as the clutch plate could suddenly engage and knock whatever you use to nudge it into you or so other parts of the engine.

Or if you're an old school DIYer, just take out a set of feeler gauge and see what the clearance is.

__________________
2006 Infiniti G35
2001 BMW 3.0I E53 X5 Build date 08/2000 SOLD
Lotus Europa 1970 Destroyed by fire
Lotus Europa 1970 S2 Renault Powered
Lotus Type 52 1970 Twincam Webers Powered
PORSCHE 911 Targa 1982 The Garage Queen
Audi Avant donated to Kars for Kids
BMW 525IT Sold
Audi 4000CS Quattro Sold
Jensen Healey Lotus Powered Sold
Opel 1900 Sold
Triumph Spitfire 1971 Sold
Triumph Spitfire 1968 Sold
Plymouth "Cuda" 340 Six pack SOLD