LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums

-   4th Gen F-Body (
-   -   Question Help diagnosing AC problem (

Black Bullit 04-15-2017 11:23 PM

Help diagnosing AC problem
My car is a 96 Z28 with the LT1 engine in it.

Okay, so the car was idling with the switch set to window defroster ( nice day, didn't really need AC ) which I now know still activates the AC compressor. I hear the engine idle go down and up as if it's struggling to keep running. Then I see smoke coming out from under the hood. I pop it and look inside to see what's up. I see the smoke coming from the AC compressor as well as a spark or two. It isn't making any funny noises. I've always been told that if the compressor goes bad, it'll make noises like metal nuts in an empty can. All I had was the sparks and smoke.

How can I tell if it's just the clutch, or if the entire compressor is bad? Obviously just the clutch is cheaper and easier since I won't have to disconnect any lines. But it's an $80 part and if it does end up being the compressor, a new one of those is $180 and it includes a clutch. So I really don't want to waste $100 ( plus whatever other parts are needed ) and deal with flushing the system ( something I can't do ) if I only need a clutch. But if I do need to do all that other stuff, I don't want to waste an additional $80 on a clutch I don't need.

cocobolo95 04-16-2017 08:00 AM

To better help you with your problem, always put the year,make, model, & engine you have in 1st post of each thread you start.

You can test compressor clutch by removing ac compressor relay in underhood electrical center. Put a jumper wire in terminals 85 & 86 where relay was. That would be the terminals with a pink wire & a dark green/white wire.

Turn ignition switch to on. Compressor clutch should engage. Let it stay on for about 10 minutes. See if it starts sparking and/or smoking during this time. If yes, you've found the problem. If no, turn ignition off, Keep jumper wire in place.

Remove serpentine drive belt from compressor. Spin pulley by hand. It should spin freely, but still have a little resistance because of the grease in the bearing. If it passes test turn ignition back on.

Compressor clutch should engage again. Spin compressor clutch by hand again. It should be very hard to turn it with clutch engaged, but it should spin by hand. If you can't move clutch now, compressor is most likely no good. If it does spin move to next test.

Put belt back on.

Start engine, turn ac on. Cooling fans should come on and compressor clutch should engage and ac work. Watch compressor and belt for signs of failure.

Black Bullit 04-18-2017 10:22 PM

Thanks for the response. I haven't had time to do your trouble shooting, but I do appreciate the reply. I updated my post with my car info. So I'm working on the assumption that the compressor is bad and researching costs plus how to fix it myself.

I'm seeing that the compressor when it goes, can send metal through the system. Some places say to flush, some say to replace the condenser as well. It also says I should replace the expansion valve and dryer. Here's my question. If I replace the condenser, EV, and dryer, is there any reason to flush at that point? All that's left are the lines. If there is debris in the lines, then shouldn't I flush BEFORE I replace all the parts? Let me simplify my question below:

Do I even need to flush if I replace all those components?

If so, should I flush before or after replacing all the components?

cocobolo95 04-20-2017 07:55 AM

Even if you replace condenser & valve assembly, you have to flush the rest of the system. Metal particles will be in evaporator & lines also. Any junk left in system will destroy your new compressor.

After flushing, new oil of the proper amount & type must be added to new compressor & components. Info is in 96 service manual at

Also do not get a rebuilt compressor. Most are junk. Buy a new compressor.

Black Bullit 04-21-2017 01:44 PM

Well, I would also be replacing the evaporator and condenser as well. But you say I'd still have to flush because there's junk in the lines? What about my other question. Should I flush before or after swapping all those parts?

cocobolo95 04-23-2017 02:32 PM

Any remaining parts should be flushed before you add new parts to the system. If lines are only thing left, flush them while they are taken apart. Then cap them afterward to prevent new stuff getting in.

Black Bullit 05-30-2019 06:20 PM

Thanks for the reply, even if I'm saying it two years later.

I've just been driving the car without AC all this time. It's a T-Top car and I don't drive it in the winter, so it's actually not been too bad. However, I'm tired of hearing that clutch making all the noise due to the locked up compressor. I leave the fan "off", but it's still rubbing or something. So I'm going to fix it this summer.

Question about the compressor. I know everyone says buy new, not remanufactured. And to cap the lines after flushing. Where can I get caps to plug the lines? Also, is there any brand of new compressor I should avoid? Rockauto has a UAC brand pretty cheap, but I don't want to buy complete junk. The AC Delco is about $50 more. Should I spend the extra or risk it with the UAC? Both options are for a new compressor.

cocobolo95 05-30-2019 08:15 PM

The caps usually come with new parts. You might try ebay for the ac caps.

If you can't find them, I use a small piece of cloth stuffed into the hole. With the end hanging out. Then I use silicon sealant to seal the hole. When ready to use, you remove silicon and pull cloth out. The cloth keeps silicon from getting inside the parts.

Black Bullit 05-31-2019 10:26 PM


Originally Posted by cocobolo95 (Post 995293)
The caps usually come with new parts. You might try ebay for the ac caps.

If you can't find them, I use a small piece of cloth stuffed into the hole. With the end hanging out. Then I use silicon sealant to seal the hole. When ready to use, you remove silicon and pull cloth out. The cloth keeps silicon from getting inside the parts.

No thoughts or suggestions on brand of compressor? Is UAC any good?

cocobolo95 06-01-2019 08:05 AM

When in doubt, always go with the AC Delco. Even though the compressor will be made offshore, the quality control will be much better than other brands.

All times are GMT -5. The time now is 09:12 PM.

Powered by vBulletin® Copyright ©2000 - 2019, vBulletin Solutions, Inc.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright © 2005 - 2011 by

For the best viewing experience please update your browser to Google Chrome