BMW X5 3.0i 3.0L A/C Compressor will not engage. System full, code 125

VEHICLE:  2001 BMW X5 3.0i 3.0L, L6, MFI, DOHC, Eng Desg M54, Siemens MS 43

MILEAGE:  55,495

Customer Concern:

Compressor will not engage. System full, code 125 present in the engine control module. When the code is cleared, the A/C compressor engages for about 10 seconds and quits. High side pressure is about 200 PSI.

Tests:

1.  At the connector for the electric auxiliary fan, check for constant battery voltage on the Red/Blue wire.

2.  Check for ground on the solid Brown wire.

3.  After clearing codes in the Engine Control Module (ECM) and the Heating, Ventilation and Air Conditioning (HVAC) system module, and cycling the ignition key, backprobe the small Black/Green wire and check for voltage pulse immediately after starting, as the ECM checks function of the fan.


Potential Causes:
Auxiliary Fan
Wiring

Confirmed Fix:

Replaced Auxiliary Coolant Fan

Tech Tips:
Fault code 125 is for auxiliary fan actuation.  The A/C compressor clutch will be shut off if the auxiliary fan cannot be made to operate