^I believe your fan should run when the vehicle gets up to a certain temp independent of the AC system if you want to let the X idle and watch for the fan to turn on.

As for the AC system line pressures would definitely assist in a diagnosis. If the coil on your compressor goes the clutch will not engage and the compressor will need to be replaced. Unless the coil and clutch can be serviced but I don't think I've seen that done.

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2005 X5 4.4i Build 04/05 Maintenance/Build Log
Nav, Pano, Sport (Purchased 06/14 w/ 109,000 miles) (Sold 8/15 w/121,000 miles)

2006 X5 4.8is Build 11/05 Maintenance/Build Log
Nav, DSP, Pano, Running Boards, OEM Tow Hitch, Cold Weather Pckg (Purchased 08/15 w/ 90,500 miles)

2010 X5 35d Build 02/10
Nav, HiFi, 6 DVD, Sports Pckg, Cold Weather Pckg, HUD, CAS, Running Boards, Leather Dash, PDC, Pano (Purchased 03/17 w/ 136,120 miles)