The A/C clutch on my ’89 needs replacing. Tld-corvette shows two different ones, depending on whether one uses R12 of R134 (http://www.tld-corvette.com/products.asp?dept=628). That seems like a no-brainer since I’m planning to have the system converted to R134 soon anyway.

Is there anything else I’ll need to consider on this issue? Other vendors that I should check with (Autozone, etc. seem to sell stuff many on the forum don’t like)?

 

New one on me - the clutch is there to engage the compressor - there's no reason for there to be any difference.

Autozone sells the FactoryAire brand which has a poor reputation though the clutch assembly simply has a different appearance from the OEM unit. As a bonus, it usually includes the shim kit - the OEM unit doesn't.

 

Well, that's what I was thinking...maybe someone with alot of experience on A/C stuff can weigh in?

 

The guys who do it for a living hang out on the Board here: www.ackits.com

 

Site doesn't show a clutch...only has new and reman. compressors. any other ideas, y'all?

 

The only thing I can think of is the placement of the diode. At some point, GM incorporated it in the clutch coil and not in the harness. If you compressor is original, I'd stick with what it came with. Clutch engagement is controlled by the Low Pressure Switch (until '90 when the ECM/PCM took over) and all of the C4's - from '88 forward - use a Nippondenso compressor, model 10PA20C. For the LT motors, the manifold is reversed, but it's the same compressor. An R134 conversion for this Year is problematic because fan control cannot be reprogrammed for the higher operating pressures that you can get with this gas. Nothing about it however has anything to do with the Compressor or the Clutch. If you want more, join the Board at the site I gave you and ask those guys - it's where I go when I get stuck on something whether it be mobile or stationary a/c.

 

Thanks for the info and the suggestion. Do you happen to know if an a/c clutch that's going bad can hold the engine back for a second or two and then free up? I'm having a hesitation/stumble problem and have checked a WHOLE lot of stuff and haven't found a problem and wonder if the clutch could be the bad guy in this.

 

Anything is possible, but I've never seen the clutch as the cause of a hestitation/stumble nor will you find it any trouble tree. Scanning it would help - you want to see what the ECM does in response to the a/c signal. At idle, it should increase IAC counts and injector pulse width. Mine ate 2 ECM's - when new - when the ECM didn't do what it was suppose to with the clutch engaged.

The ECM does compensate for normal compressor load, but it can't compensate for a bad compressor or one that's about to seize or has seized. Most start to stall and will stall once it's locked up. The basic check is to remove the belt and see if you can turn the shaft (outer hub) by hand. If so, then it's probably ok. If not - or if you have to wrench it over, it's gone.

You can also check the air gap - should be .020 inch between the outer hub and the pulley. Too big and they'll make noise and potentially cause a driveability issue - too small and they start to stink. Do check for oil on the hood above the compressor - the Nippodenso has an appetite for shaft seals.

The '89 isn't a flawless engagement; ie, you can usually feel or sense engagement. It's not controlled by the ECM and the Controls simply sends a voltage signal to the ECM when you hit the on button. Signal is removed once the Low Pressure Switch Contacts open or if WOT is indicated by the TPS. Other than that, the ECM assumes the clutch has engaged and starts adding fuel for the load.

You might also check compression or look for signs of a weeping head gasket at #7 which is a known issue for 113 headed Vettes and a more common cause of driveability complaints. Often missed as we seem more apt to blame something with some sensor.

 

Hey, thanks so much for your continued help! I talked with the guy who does my A/C work today, and he's going to give me a quote for a new compressor and the conversion to R134. He said that with the oil line that's on my hood I definitely want to go w/a new compressor. He also felt he could do much better on the compressor's price, so I'm hopeful.

Thanks again!

 

My clutch is just noisy. When disengaged you can hear it a mile away. when I turn on the AC and it quiets down (obviously). Is there a way just repack the bearing or something cheap?

 

The AC clutch pulley bearing can be replaced by itself. 88-96 used the
same bearing. The bearing is pressed into the pulley item #3 in the picture.

Advance Auto sells the bearing for around $18.00.

http://shop.advanceautoparts.com/web...pulley+bearing

 

Thanks!!! I called Advanced and they had it in stock! On my way to pick it up now. Is it tricky changing it? I have the service manuals so I'm sure I can handle it, but just wondering.

I am so glad that I joined the Forum!

 

The service manual says you must discharge the AC system before you can service the clutch because of the way the hoses come over the front of the compressor.

People have worked on /replaced the clutch with out discharging the system. You may have to carefully pry the hoses up a little bit.

Break the small bolt loose at the front of the compressor before
removing the serpentine belt. The torque is about 10 ft. lb.
The pressure plate should pull off. Remove the shim and a snap ring.
The pulley can then be pulled off.

Here's a post where a member posted some pictures of his complete
clutch assembly replacement.

http://forums.corvetteforum.com/c4-t...lear-92-a.html