I recently bought a 90 740t with dead a/c. The previous owner did not even know it had a/c, though he had the car 6 yrs. I've read the faq's and they deal with mostly dead a/c. Before I go to the expense of converting etc how can I determine what works now, ie compressor clutch etc. A troubleshooting flow chart for a/c with no known history would be ideal. Thanks in advance, because, I got stuck in a ferry line up @ 35C last weekend. My wife and two year old say never again.