SILVERADO AC

my son is looking at a 1999 chevy silverado. its in pretty good shape, hasn't really been driven over the past year. always garaged and kept up well. the only thing we found wrong was the ac does not work, or I should say blows warm air. could be a wide range of things from basic freon to who knows, compressor maybe. obviously I know I need to bring it in somewhere, but just checking if anyone ever had similar problems with a similar truck that could maybe give me some leads. thanks for any info. hogone

this vehicle was very well taken care of, it actually lived right across the street from me and I've known it since he bought it. tires are like brand new. very good thorough maintenance log; actually not really that much done except oil changes every 3500-4000 miles, and a few minor repairs. it was his pride and joy but he no longer is able to drive. just concerned about ac. obviously it can be fixed, but what it is and how much is the concern. hogone   

Hey Hogone,

I am a big fan of Silverado's, just sold a 93 that had 340K on it. The fact that it has been sitting a year, makes me think it has a slow Freon leak. Hoses and belts should be checked and replaced as appropriate. Take it to a certified AC repair center. They do not have to fill with Freon, they can pressure check AC with nitrogen. Big price difference. If it was me I would bypass pressure switch and see if compressor runs. If it does the Freon is low. Once pressurized they can check for leaks. Once leaks are fixed, they can fill with Freon. Relatively simple repair. Belts don't cause loss of Freon, hoses can but are easily detected. If compressor is bad, it won't ever come on. Just pick a good place to take it.

Hogone,

Yeah it's low on Freon. 4 years is awhile, sounds great you have a log. All your symptoms are low pressure. What they do is start and stop. Near the accumulator is the switch, you can jumper it, but with low Freon you may or may not get cold AC. It can't run on low pressure. If I could look at it I could help. Sounds like a sweet deal. The low pressure switch is a two prong switch with a plug on it (a connector), it won't let the compressor come on with low pressure. I checked YouTube and they have some informative vids. A good AC dude will figure out in 5 mins, I could.

Does the compressor clutch actually engage? Yes, then no refrigerant left in the system. NO, then the A/C clutch fuse and relay should be checked for correct operation.