AirCon/Radiator fan problem XC70MY01

[Ninox]

My Volvo XC70 2001 with climate control has a problem with the air-conditioner. When used, the aircon works normally for up to 20 minutes but then blows warm moist air. When this is happening I notice that the radiator fan is not spinning. Engine and turbo cooling appear to be operating normally and the fan definitely works after using the car at low speeds. The system has been regassed and checked for leaks as the gas overheats and escapes when used. The climate control works well when only requiring the heater and the air-con is turned off. A mechanic told me I need to replace the $900 fan. Unless the logic circuits are located in the fan this seems unlikely to solve the problem. However, I don't know which component is likely to be at fault in not activating the fan.
Any help greatly appreciated.

[howardc64]

There was a recall campaign on the fan. Not sure of the status in AU. Might check this first.

http://www.faqs.org/car/volvo-v70xc-2001/engine-and-engine-cooling/#recalls_0

[Ninox]

Thanks for the response. I've owned the car since 2007. My nearest Volvo dealer had plenty of opportunity to diagnose the problem, but they would just re-gas the system every time. I really need something to point them in the right direction and I guess the recall list is a good starting place.

There was a recall campaign on the fan.