no high speed radiator fan when air conditioning is turned on?

So, I would check the dark blue wire for 12 volts at the blower control module when the key and HVAC system are on. Then check the black wire for ground with the control module unplugged. If these tests are good replace the blower control module here is the location of the module and the wiring diagrams for the blower motor so you can see how the system works. Check out the images (below). Please let us know what happens.

thanks for that but i was referring to the high speed radiator fan. i was under the impression that as soon as the air conditioning was turned on that the radiator fan motor would go to high speed.

Gotcha, the radiator fan comes on when the AC is on but not the high speed which is only used for:

1. engine coolant temperature rises enough
2. A/C high-side refrigerant pressure gets high enough
3. airflow demand increases at idle or in hot weather

I hope this helps,