Q. I own an ’87 Nissan Maxima. Yesterday, on about a half-hour drive, my air conditioner worked fine until I was on the road about 15 miles. Then it sent through only hot air. After parking for two hours, it worked fine again until I had driven about the same distance when it again produced only hot air. I shut it off and restarted it about 15 minutes later and it worked fine. I think I have a