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Help with A/C diagnosis?

Hi all

Re: 1996 Chevy Silverado 1500 w/Vortech 350

Just warmed up enough here to turn the A/C on for the first time the other day and it blew hot. It was working fine last season, so I figured it just needed a recharge.

I bought a kit with the hose, gauge, and can of refrigerant. Everything seemed pretty straightforward. It said if the compressor didn't run, to empty the whole can into it, it said it would only fit one valve, and it had green (low), blue (filled), yellow (alert), and red (danger) zones.

I start the engine, and sure enough it's in the blue. Compressor not running.

Attach the can, open it up - goes instantly to red. turn off can, back to blue. Turn it on, back to red, off - back to blue. I'm sensing a pattern - just let it fill for a while.

It fills and fills and fills - still nothing from the compressor. I start to suspect something electrical.

After about ten minutes - the compressor comes on for about 2 seconds. Well - it's not electrical.

I turn the can off and take a reading - there's a pattern. The gauge goes up to nearly the yellow zone in the green, the compressor comes on for two seconds, knocks it to the blue/green borderline, pressure builds back up to the green yellow line - repeat. Basically the compressor comes on about 2 seconds out of every 15.

I disconnect the can - it's about 3/4 full!

I try adding a bit more - doesn't seem to take it - and the connector "spewed" when I disconnected the hose.

I realize now I'm probably not looking at a DIY repair. It would be NICE if I could fix it, as I'm driving 5 hours tomorrow. But mainly at this point I'd like to have an idea of what to expect at the mechanic - what to say or what not to say - what to expect, etc.

I have a feeling I shouldn't even mention I tried to recharge it. "Uh - no - of course that didn't work, because you need a whole new system". I just don't want to walk in somewhere looking like a gaping billfold to someone.

Any ideas what might be going on - what to expect, what to say?

Can I assume, A) it's charged, B) it's not electrical, and C) the compressor's not frozen up?

Thanks for any input! Kevin

Reply to
Kevin Highsmith
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The best solution for you is to take it to a good A/C shop since you do not understand the operation nor how to troubleshoot the problem. They will know you tried to charge it due to the oil around the low pressure fitting from connecting and disconnecting. Another item to light your paranoia of service shops is the problem may be a hole in the condenser in front of the radiator. A very common problem anymore is punctures in the condenser due to rocks hitting them so be prepared.....

Reply to
Woody

The method they give you is for the first can on a completely empty system. In your case the system isn't completely empty, its just low. in a low charge situation this method will never charge the system. You have to find the low pressure cutoff switch and jumper it so that the compressor will continue to run while you are charging.

That being said you really should take it to a shop and let someone who knows what they are doing look at it. Those bargain cans aren't a bargain. You are only seeing one side of the picture with that can... You have no idea what is going on with the high side and you realy have to see the whole picture to charge the system properly.

Steve B.

Reply to
Steve B.

just guessing the system is low on freon, needs charging / checked for leaks.

you ask what to do, go to a reputable ac repair shop, ask for a diagnosis and zip the lip. They'll tell you what is needed / cost.

a c systems are too expensive to screw with for most do it your self mechanics.

an a c unit is designed to where the compressor will cut-out on a low-pressure condition.

m h o =A0v =83e

Reply to
fiveiron

Assuming it really is a cycling clutch system (not all the modern ones are)...

Sounds like you'd need to bridge the low pressure switch to get in enough refrigerant to prevent it from short cycling on the switch. It's fairly normal procedure to have to bridge the switch for recharging an empty system.

You're hardly likely to make a fool of yourself if you've worked out the trick only the expert is supposed to know. :)

Probably not much point in recharging it without repairing the leak that's caused the original refrigerant to escape. For which you'll need someone who has all the necessary gear and expertise.

Very likely the problem will be the compressor shaft seal (does it have any oil coming out behind the clutch?), which can usually be replaced for a lot less than the price of a new compressor so long as the old one hasn't done an exceptionally high mileage. Finding someone who's equipped to fit the seal might be the hard part, but at least you should probably ask if it's repairable before a new one goes in (if that's deemed to be the problem).

A) no, B) probably yes, C) yes

Reply to
John_H

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