AC Compressor Clutch

[Billy Mild]

Has anyone looked into replacing just the AC Compressor Clutch before? My AC works fine, but makes a ton of noise while the compressor is running and cooling. It makes a horrible clicking sound from time to time and varies with RPM. I think the clutch is going out honestly. I hate to crack the whole system open when it still has R-12 and works fine.

[A26B]

I've never been able to find an AC Compressor clutch for the LT5. It is unique to the ZR-1. I tried to have them manufactured a few years ago & ran into insurmountable problems.
Let me know if you find a source, but beware of false compatibility


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[Bruce]

Ive just been down this road this week in fact. You mention the AC Compressor 'clutch'.

I am assuming you mean the part that is magnetically attracted to the belt driven pulley that enables the compressor to work?

I found parts so damn easy to get, had them in my hand overnight. My compressor is just a standard Denso 10PA unit which is used on many other vehicles.

[Billy Mild]

I believe it to be the AC Compressor Clutch. The AC works great, just makes a ton noise once in a while.

[Bruce]

Well the 'clutch' is actually a cast iron ring that is attracted to the driven pulley, by magnetism - there is a electromagnetic coil in behind the driven pulley that 'pulls' the compressor drive ring against the driven pulley to drive the internals of the AC compressor. Mine was doing the same, making a hell of a noise every now and then.

What happened to mine was the double bearing race that supports the driven pulley, collapsed. The ball bearings fell out of the race and the inside of the driven pulley ran metal to metal against the electromagnet coil and severely overheated all and sundry connected to it. It got so hot, the driven pulley turned blue. The smoke coming out of my bonnet was the melted shelack off the magnets coil windings.

Knowing now what I know about the 'sound' etc, I would have pulled the driven pulley off sooner and replaced the bearing race. But it failed just before I got around to it.

[-=Jeff=-]

I really wish the 10PA20 would fit instead of the 10PA17 in our cars

[G8nightman]

Well the 'clutch' is actually a cast iron ring that is attracted to the driven pulley, by magnetism - there is a electromagnetic coil in behind the driven pulley that 'pulls' the compressor drive ring against the driven pulley to drive the internals of the AC compressor. Mine was doing the same, making a hell of a noise every now and then.

What happened to mine was the double bearing race that supports the driven pulley, collapsed. The ball bearings fell out of the race and the inside of the driven pulley ran metal to metal against the electromagnet coil and severely overheated all and sundry connected to it. It got so hot, the driven pulley turned blue. The smoke coming out of my bonnet was the melted shelack off the magnets coil windings.

Knowing now what I know about the 'sound' etc, I would have pulled the driven pulley off sooner and replaced the bearing race. But it failed just before I got around to it.


Please list part #'s qand source I replaced my compressor because could find the part's new compressor was $400 from denso.

[GOLDCYLON]

Well the 'clutch' is actually a cast iron ring that is attracted to the driven pulley, by magnetism - there is a electromagnetic coil in behind the driven pulley that 'pulls' the compressor drive ring against the driven pulley to drive the internals of the AC compressor. Mine was doing the same, making a hell of a noise every now and then.

What happened to mine was the double bearing race that supports the driven pulley, collapsed. The ball bearings fell out of the race and the inside of the driven pulley ran metal to metal against the electromagnet coil and severely overheated all and sundry connected to it. It got so hot, the driven pulley turned blue. The smoke coming out of my bonnet was the melted shelack off the magnets coil windings.

Knowing now what I know about the 'sound' etc, I would have pulled the driven pulley off sooner and replaced the bearing race. But it failed just before I got around to it.


What did it sound like ?

[Bruce]

What did it sound like ?

It was a rumbling, dry bearing sound. It would come and go .. then it went!

Im trying to think of what might sound similar but cant think of anything. If you have access to a bad alternator for instance, with buggered bearings, give that a spin and you will know the sound.

[Bruce]

Please list part #'s qand source I replaced my compressor because could find the part's new compressor was $400 from denso.

I just looked online at some local suppliers and here are a few links to stuff that are the same.

http://www.totalair.co.nz/product/clutches-clutch-assemblies/45/

That one above looks identical to mine.

Check out these individual parts, they are some of the ones I got to replace mine with, the bearing and the magnetic coil

http://www.autoair.co.nz/shop/Shop+by+Product+-+Retail+prices/COMPRESSOR+PARTS.html

Here is the clutch plate
http://www.autoair.co.nz/shop/Shop+by+Product+-+Retail+prices/COMPRESSOR+PARTS/-CLUTCH+PLATE/CLUTCH+PLATE+DENSO+10S++10PA+CLA7000.html

This company above has just sold all their spare parts to a business called "Cool Drive" in Auckland New Zealand, I just phoned them and within 12 hours had all the new parts.

[A26B]

Bruce,
What did you do for the pulley? That's the part that is unique to the ZR-1/LT5.

[Billy Mild]

So would you replace the bearings themselves inside the clutch assembly?

[Bruce]

Bruce,
What did you do for the pulley? That's the part that is unique to the ZR-1/LT5.

I just pressed the old bearing outer, out of the pulley and put a new bearing in the pulley.

I didnt see a need to change the pulley as its in one piece. I would find it surprising though that a huge expense of specific tooling would have been done just to produce a 'special' pulley for so few engines.
Im sure it would be used on some other car ... trick is finding which one!

[Bruce]

So would you replace the bearings themselves inside the clutch assembly?

Yep, I just replaced the bearing, its the only bearing in the whole clutch assembly.
Thing is, its one of those bearings that is running 'all' the time whether the AC is engaged or not. Like the belt tensioner bearing, it runs all the time, so I'll change that as well, even though it seems ok. The tensioner bearing is not affected by the heat soak from the engine as much, as its not bolted directly to the engine block, it runs quite cool. But the other bearings like the alternator and AC ones etc run at engine temperature - and they get bloody hot!

[A26B]

...........I would find it surprising though that a huge expense of specific tooling would have been done just to produce a 'special' pulley for so few engines.
Im sure it would be used on some other car ... trick is finding which one!

You may be right, but I haven't been able to find it yet. I can attest that there are quite a few LT5 specific parts that are unique, such as the serpentine belt tensioner. Some pieces of the tensioner are shared but the main spring housing is unique.

Insofar as specific tooling requirements, CNC machine tools were well advanced by the time the LT5 was born. CNC eliminates nearly all of the special tooling requirements that would have been associated with the pre-CNC era.

There was no hesitation by GM to spend big bucks on special machine tools required to perform the cam journal boring on the cylinder heads. I have no doubt that if the AC Pulley needed to be unique, then so be it.:-D

BTW, I thought your pulley "turned blue" from the heat & became toast. That's why I inquired about the pulley, and that the pulley has a friction type of material to prevent metal to metal contact.

http://i190.photobucket.com/albums/z224/A26B/43f79579-39d5-47bf-a847-7b06e1efc06d_zpsm8phcadf.jpg (http://s190.photobucket.com/user/A26B/media/43f79579-39d5-47bf-a847-7b06e1efc06d_zpsm8phcadf.jpg.html)

[Bruce]

Just an update as to where Im at.
I machined up the mating surfaces of the pulley and the compressor drive today. They were out about 0.5mm and the mating surfaces were only touching on a few very small places. So I machined them all flat and they all touch together now.

The picture is of the magnet - it burnt up because when the pulley bearing collapsed, the pulley then rode on the top of the magnet - metal to metal, which cooked it.

While I have the front of the engine so to speak, Im doing all the bearings and the water pump bearing as well.

Tell you what - I cannot believe all the loose bolts on the engine. I found one I could undo off the water pump by hand! I hope I dont have a 'Monday' engine haha.

I went over as many bolts as I could see and tightened down every one - and they were all loose. :/ What were they doing that day at Mercury?

One bolt on the water pump is so tight though I cant get it off, and the head has rounded - and of course its in the worst possible place. I'll wait till tomorrow and borrow a special tool from my mate to get it off. Some of the bolts were so farking tight I had to use a power bar to turn them. Thank god for American Steel.

All I have to do now if figure out how to post photos.

[Bruce]

Failed compressor parts.

The first photo is of the compressor pulley. I refaced the mating surface as it was 'all over the place' and the hub would only be connecting with a very small footprint. I resurfaced that too (the part on the left of the left photo). You can still see a small piece of the surface that has a hollow. I didnt bother cutting any deeper as there is now plenty to 'grab' onto.
The right hand photo is of the toasted magnet. This part sits inside the pulley. It melted all the resin from the windings when the bearings (shown with it) collapsed and the inside of the pulley fell down onto the magnet assembly and just ran metal to metal till it burnt. Yes, there was smoke in the car, smoke coming out from under the bonnet. Great spectacle for people waiting at the traffic lights.
:-D

[BigIke]

My pulley just went up in smoke today. :)

Is the clutch replaceable with the intake in place? I don't believe it is, probably just go with a reman unit...

[Bruce]

My pulley just went up in smoke today. :)

Is the clutch replaceable with the intake in place? I don't believe it is, probably just go with a reman unit...

So its not just my driving style then! Someone else has the problem

You have to take the intake horn off to get to the clutch plate or pulley. I took my whole plenum off because Im doing the water pump as well so it made it easier to get to everything like that, but yes, you can get to the clutch and pulley with the intake horn off. The clutch plate is held on with one 10mm bolt and it just slides off. The pulley and magnet armature are held in with a circlip and comes off just as easy.

[BigIke]

I'm 7.4k almost every shift from 1st to 3rd (no second gear lol)... So I had smoke pouring out of the clutch yesterday, the ac wasn't working, think I need the clutch or just get the assembly?

Could you tell me the part you used (link) and if modifications an absolute necessity? I don't have the equipment to face the parts.

Thanks! Jay

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[Marc Haibeck]

Like Bruce say's, the bearing can be pressed out of the pulley and replaced. In the US Santech has PN MT2027 for the bearing. Autozone sells them for $18.

[BigIke]

Thanks Marc (loving your chip BTW, fixed all my cooking issues, some day I'll send it back to take a little timing out, I have to run booster in the summer...), sorry buddy I didn't do my due diligence and read the post fully. I'll get the part and a new belt, might install today.

Perfect time to powder coat my intake Competition Gray, upper and lower. Don't know if the cam covers will come off with the engine in the car... Going to match my engine to the C6 comp gray GS wheels. ☺

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[Z51JEFF]

Hi Bruce,I sent you an email.