I have a 1993 Trans Am LT1 with 120011 miles that has an issue with the A/C. The A/C usually doesn't work when first started, but I turn the engine off after running a few minutes and then restart the car, the A/C works. Sometimes it stopps running while driving for a while, but if I pull over, turn off the car and restart the car it works again. Crazy huh? Any suggestions? Thanks.

Have you verified that the compressor is what's disengaging?

You would have to troubleshoot the circuit but it could be any number of things like a weak clutch magnet, bad relay, bad switch or poor connection anywhere in the circuit.




78 Corvette Pace Car For Sale-18k mi orig-Florida

As said by Hammer - you need to know if compressor is engaging. It is totally pressure related to enable it which engine heat would do if way late. It could be some other issue but the common one is low charge and this car the weak link is the shaft seal in compressor. If found all oily it's a strong clue. Refrigerant gasses will increase pressure rather dramatically with higher temps if only engine heat.

Have charts and couldn't find it? R-12 or a 134a system in this car? Either fine - the approach changes.

At least where I am near 75% of issues if I read this right would be low charge from a leak which is to be found and fixed. Let's take that on when we know pressures with compressor engaged and performance/temp observations.

Clutch (A/C) air gap should be about .020. Easy check - take a standard biz card and it would fall out of the gap. Tightly folded it should barely get in that gap. You want that gap as close as possible without any drag when off. Takes tool - almost sure on this car to adjust that if needed at all.

Note: When A/C is low on gas it doesn't carry oils for compressor well that flow along with the gas. If that, it creates a monster to fix up and tons more bucks!

T
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Tom Greenleaf - MetroWest, Boston

Let me just caution you one one thing. Although low refrigerant is a possibility, don't just arbitrarily add more without knowing what the situation is or you can do a lot of damage if you overcharge it.




78 Corvette Pace Car For Sale-18k mi orig-Florida

EXCELLENT POINT AND WARNING! Hammer - that was great. So many ill labeled kit things that suggest just blasting in more gas with a fool, inaccurate gauge will destroy a system that might have needed a minor fix!

Folks - don't be fooled that all problems get fixed with what is called in the trade "Death Kits" that can both destroy system and risk of hurting you as well! A/C is NOT just a "filler up" type idea at all,

T
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Tom Greenleaf - MetroWest, Boston

Thanks guys. I will check pressures with my gauges. My first impression was the refrigerant was ok since it blows really cold air, but checking it is easy. The relay is good since I replaced it with another I knew was good. I'll check that gap with my feeler gauge for accuracy. I let you know wnhat I find. Thanks

Just to add on clutch air gap:

Biz card works as good as any - real feeler gauges can be tricky!

Listen to Hammer! Just adding refrigerant is both dangerous and destructive if you don't understand that it needs that or just how. Overcharged systems can self destruct - know that! You get cold air sometime is a good sign that the "charge" may not be the issue at all - know that too.

Also: Don't put anything in the A/C part that car didn't call for originally. You can buy or my have a hose and use 12oz pure stuff thru your gauges if you don't want to buy a 30lb bottle - understood. Purge lines of air - a huge enemy,

T
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Tom Greenleaf - MetroWest, Boston












(This post was edited by Tom Greenleaf on Sep 30, 2009, 9:30 AM)