Chevrolet: air conditioning, grand prix gtp, pontiac grand prix gtp

Question
My cars not a chevy but it is gm 1994 pontiac grand prix gtp 3.4, about a year ago i had the alternator and connector block replaced and every since my car will only blow hot air it doesnt matter where you put the temp. at cold or hot doesnt matter, it also will only blow out if the head lights are on the mechanic that did the repairs really has no idea why can you help me?

Answer
Hi Stacy, this a strange problem. The heater\Ac controls are powered by vacuum, maybe when he replaced the alternator he pulled off the vacuum line(just a guess). You should buy a manuel on your car, this will help you understand how the system works and wiring diagrams to check for short in the electrial system. I hope his helps you. Regards, Keith.