I was hoping it was somthing easy to replace like a switch or sensor. I'll deal with the issue when I can afford to. Just put 5k in the X5, so need to hold off.

I hear you. Just a thought though. If you spent 5K this might be a good time to take advantage
of that good relationship with that indy or SA at the dealership. See if they'll give you some
free diagnosis time. Wont hurt to try. I've had the people who work on mine drop a switch or
sensor or provide a quick service at no charge. (had to pay for the part)

Does your engine have only the electric fan?

Nope I have 2 fans

The auxiliary fan should come on when the A/C is turned on, when the engine overheats and for 5-10 seconds when you first start the engine.

The auxiliary fan does not come on immediately when you turn on the AC. The pressure in the AC system along with the ambient temp and the temp in the condenser determine when the fan comes on.

Oopsie, you are correct the aux fan does not immediately come on when the air is turned on. Per my handy dandy Bentley manual the aux electric fan is controlled by the ECM based on the following inputs to the ECM:

Radiator outlet temp.
Calculated catalytic converter temp.
Vehicle speed
Battery voltage
Calculated refrigerant temp.

When the vehicle is started the ECM activates the aux. fan briefly at 20% of max. speed for the purpose of diagnostic monitoring.