A/C problem

[chevy_29]

On my 03 trailblazer the a/c has been working fine until today. I started the vehicle here at home and drove to the store about 10 minutes away. The air blew cold and fine. I left the vehicle running while I was in the store. When I came back out it was not blowing cold air. I opened the hood and the compressor was not engaged. I tried to get it to come back on for a while and nothing happend. I parked it at home for a hour or two. I left again in it and the air was cold again. Drove it about 10 minutes and worked fine. My question is if it gets low on freon will it do that. I have only had a vehicle to quit blowing cold for good not off and on. If so there is a port on the dryer with a little end and the line by the radiator has a port, big end on it. Which one do you put freon in. The big in line or little on dryer? If anything else might cause this please help me out?

[brcidd]

Next time this happens, (compressor is off when it should be on) find a blunt object, broomstick, whatever and tap on front of compressor, see if armature plate pulls in, if it does, keep reading... your air gap is too wide and a shim needs to be removed.

Air gap (distance between armature drive plate and pulley face) should be near .020" yours is probably near .050" if you have higher mileage on your TB.

The electromagnetic field can pull in the drive plate when coil is cool, but has trouble when coil warms. Once pulled in, it will stay in, but once released, it will not pull in when warm. Seen it a bunch of times. You'd be surprised as to how many compressors get replaced for this common issue.

Shims are behind drive plate, bolt (or nut) on front of compressor needs to be removed and drive plate wiggled off, then be careful to remove the thickest shim (if more than one). Replace drive plate, tighten bolt and be good to go for another 100k miles.

[maxwedge]

Multiple failures have been noted on these trucks related to a bad a/c pressure switch in the high side system.

[chevy_29]

Originally Posted by brcidd

Next time this happens, (compressor is off when it should be on) find a blunt object, broomstick, whatever and tap on front of compressor, see if armature plate pulls in, if it does, keep reading... your air gap is too wide and a shim needs to be removed.

Air gap (distance between armature drive plate and pulley face) should be near .020" yours is probably near .050" if you have higher mileage on your TB.

The electromagnetic field can pull in the drive plate when coil is cool, but has trouble when coil warms. Once pulled in, it will stay in, but once released, it will not pull in when warm. Seen it a bunch of times. You'd be surprised as to how many compressors get replaced for this common issue.

Shims are behind drive plate, bolt (or nut) on front of compressor needs to be removed and drive plate wiggled off, then be careful to remove the thickest shim (if more than one). Replace drive plate, tighten bolt and be good to go for another 100k miles.

Thanks for telling me that. I have never heard of that. Today it is raining and in the low 60's. Yesterday it was almost 80. Tomorrow it will be back warmer and I will run it and try what you told me to do. I post back tomorrow afternoon what happend when i tapped the end of compressor. Thanks for your help on this. Acouple of weeks ago i ran it and it was no problem. Ran it again last night and done fine. If the pressure switch goes bad would it cause it to act like that? I would think it would not cool at all.