I have a BMW 320d SE first registered November 2002, that I bought second hand from a BMW dealer in 2006. The aircon pump was about to fail a month ago, picked up by my estimable mobile mechanic and he advised me to keep the air con off at all times to avoid complete breakdown of the vehicle. I was not aware that the aircon should be on most of driving time and have often travelled with window fresh air, which comes free and is greener. The owners handbook gives no warning of the way to use the air con over 8 pages devoted to the aircon facility. What a let down by BMW. My mechanic estimates £1,000 for fitting a replacement of the pump or £300 if he can find a second hand one with a 3month guarantee. He says the car is in great condition apart from the pump problem and I would like to hear your opinion.