These cars are possessed by the devil! My wife bought one of these last year, and while it drives very nice, the A/C works for only seconds at a time, the blower motor ramps up and down like yours, the defroster only works at full-hot and roasts the interior while not really doing a very good job of defogging the window at all, and the windows, mirrors and locks work when they want to. Removing and replacing the battery cable gets all but the A/C working again...for a little while. My current thought is the 'Comfort Module' located...somewhere on the car. It supposedly ties EVERYTHING together for the primary purpose of making the car unnecessarily complicated and life a living hell for second hand owners.

My ratty old Jeep's windows, mirrors, and A/C have always worked fine, without any modules at all (it's a 1988).