Only Replace A/C Clutch?

[B Red Dodge]

Long time listener, first time caller...

I have an issue with my A/C that I'd like to get fixed before the summer rolls in. Hopefully someone can help out.

The clutch on the compressor is not engaging. I've checked the voltage going to the clutch coil when the system is turned on and that seems to be good, so I don't think it's a pressure switch.

I tried to hotwire the clutch coil with the engine off, one lead directly to the negative battery terminal, and one lead directly to the positive. The clutch will not self engage but if I push on the front of the clutch, it will activate/engage and hold itself there.

I want to avoid removing the compressor from the truck if I don't have to, so I don't have to mess with the freon. The whole assembly looks fairly new so if it is the clutch, I'd just want to replace that.

Any ideas?

'88 Chevy Blazer
350 Vortec/TBI
Factory AC (far as I know)

 

[MAX89K5]

You can remove the shims between the clutch and coil to reduce the air gap. That should make it engage if the coil has weakened over time.

 

[Blue85]

Also, you can tear the clutch, pulley and coil off the front of the compressor and change them without breaking the seal. You probably have room to do it all underhood without unbolting the compressor.

You're in luck because I've already taken pictures of how to do it: http://coloradok5.com/forums/showthread.php?t=307840

Also, I think I still have the coil, pulley, etc. I pulled off when I took those pictures. PM me if you want parts.

 

[Blue85]

You can remove the shims between the clutch and coil to reduce the air gap. That should make it engage if the coil has weakened over time.

Do you have pictures of these shims? I've torn into a couple R-4 compressors and don't remember anything that would allow adjustment.

 

[MAX89K5]

Do you have pictures of these shims? I've torn into a couple R-4 compressors and don't remember anything that would allow adjustment.

I have never played with a rotary compressor but every other compressor I've dealt with had the shims.

 

[Blue85]

I'm just not sure an R-4 has any real adjustment there. However, it seems like you could shore up excessive gap by removing a little material from the back of the clutch nose.

Look here: http://www.autoacforum.com/messageview.cfm?catid=2&threadid=17015

There's also the old trick of winding a bit of wire through the clutch flex part to make the static gap a little smaller. The electrical connection should also be tested. Those non-sealed terminals can get pretty bad over the years.

 

[B Red Dodge]

Thanks for the responces. Here's an update:

I measured my air gap and it was about 1/8 of an inch (0.125"). Factory '88 manual states the allowance is between .020" and .040".

I ordered a clutch removal tool set (Astro Pneumatic 7886 A/C Compressor Clutch Installer/Remover Kit ) for $30 and a clutch holding tool (Powerbuilt 648980 Air Conditioner Clutch Holding Tool) for $9 from Amazon.com which made the clutch removal/install on the truck, very easy. I didn't even have to pull the belt.

There were NO shims behind the nose of the clutch so I ended up taking my dremel w/ a sanding drum to remove about .100" from the nose of the clutch. This also ended up being the approximate depth of a chamfer for the compressor shaft hole in the clutch. I basically ground the nose of the clutch untill the chamfer was gone, cleaned it up with a flat file, and put the clutch back on.

The A/C is now working as it should.

 

[MAX89K5]

Glad to see you got it working! [emoji1]

 

[Blue85]

Interesting because I happened to come across these parts as I was cleaning up last night. I was thinking maybe the tapered part was there to let you see how much depth to remove / has been removed. I don't have any new ones to look at, but it only makes sense that as the clutch wears, the gap will open up and eventually will need to be reduced. If you were swapping parts you could always find some thin washers/shims to put in there if the gap was too small.

I think the coils are just really strong on these which gives a rather generous tolerance on what will work.

 

[panaboy95]

Thanks for the responces. Here's an update:

I measured my air gap and it was about 1/8 of an inch (0.125"). Factory '88 manual states the allowance is between .020" and .040".

I ordered a clutch removal tool set (Astro Pneumatic 7886 A/C Compressor Clutch Installer/Remover Kit ) for $30 and a clutch holding tool (Powerbuilt 648980 Air Conditioner Clutch Holding Tool) for $9 from Amazon.com which made the clutch removal/install on the truck, very easy. I didn't even have to pull the belt.

There were NO shims behind the nose of the clutch so I ended up taking my dremel w/ a sanding drum to remove about .100" from the nose of the clutch. This also ended up being the approximate depth of a chamfer for the compressor shaft hole in the clutch. I basically ground the nose of the clutch untill the chamfer was gone, cleaned it up with a flat file, and put the clutch back on.

The A/C is now working as it should.

the r4 compressors and most of the compressors on mid 80's and 90's chevy trucks and cars do not have shims. it is a press fit on the shaft. you just have to press the clutch hub on the shaft till the air gap is about .040 enough it does not drag but still will engage quickly. the nut on the compressor does not do a thing i never even put them back on. (some do not even have one) If you have the puller and the air gap is too much there is no need to take it off just press it on the shaft a little more. Glad it is working good.

 

[B Red Dodge]

If you have the puller and the air gap is too much there is no need to take it off just press it on the shaft a little more. Glad it is working good.

I would not have been able push the clutch on any further without removing material from the nose of the clutch though. Even now, if I wanted to make the gap smaller, I'd have to pull it back off and remove more material from the nose.

 

[panaboy95]

If you do it again i would put a new clutch on it. it must be worn real bad not to go on any farther. As they age they get some pretty bad grooves in the hub and pulley.