A/C unit intermittent

[odonus]

We have a 3.0D 2007 X5 with a/c problems

Itseems the compressor clutch switch is not engaging when required.

But when it does -we have excellent functionality

Keen to know if there is a schematic or a diagnosis I can follow to determine cause of this symptoms

Occasionally I am able to cycle the A/C switch on off which does not kick in the unit. But after doing this and stopping/restarting the car - I can get it to work

Thinking a bad connection somewhere - but to get to the compressor - I think I may need to get in from the bottom side.

Looking for some assistance before the weekend to determine fault.

NB: I took it to an A/C mob, and they stated it could not be fixed until I can get the unit to switch (probably lazy in my opinion) but unit works flawlessly when going

BTW - INPA shows no faults on A/C function

cheers
O