TrailBlazer AC Clutch not engaging.

Darrenp

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I have not had a chance to work on this yet as I have been sick with a bad chest cold.

I will check the air gap first.

The automatic control unit is working fine. The outside temperature is registering correctly. All functions working correctly.

As I have stated before, I have checked the low side cutoff switch by disconnecting to test the relay. The relay is OK as I have switched it with two others in the fuse box that I know are working with no change, so I know the contacts are OK.

There are no codes. Nothing done on the AC system at all since I have owned it (bought new), and it has a full charge (checked with gauges on the rare time it did run. When working, the clutch cycles fine).

I am down to the air gap or a broken wire making sporadic connection.

Darren
 

Mobile Dan

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If you feel comfortable that you can bypass/jumper the relay by looking at the little schematic on the relay (read reply #4), that may be the easiest thing to do, especially if you reach down to the clutch to help it close if air gap is the problem.

As a highly skilled mechanic, I have sometimes tapped a AC clutch with a prybar with the engine running to check for excessive air gap/ weak coil. Many vehicles these days have so little access that this would be very dangerous. Think, long pointy thing through eyeball into brain.

Hope you feel better soon.
 

kev2

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OK I always hope for the esay simple things... my thought was the charge was borderline- as its temp sensitive might have set a code.. Maybe a low charge indicator- ie refridgerant pressure sesnor was restricting AC request..

Everything I have starts with the SOS - connect TECHII.. thats Frustrating me
 

Darrenp

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Re: TrailBlazer AC Clutch not engaging. UPDATED

Well, the weather is finally cooperating when I have time to work on it. It is above 75 degrees with no rain, so the compressor is not engaging by itself.

Again, all the electrics are fine as I have tested them.

I have a 4 ft. pry bar that I used. Kiddies, DO NOT TRY THIS AT HOME!!!!

Unfortunately I had to have the engine running to do this, as the system does not energize the coil until the engine is running.

With the engine running, and the clutch not engaged, the pry bar stuck to the front of the pulley, so the coil is energizing as it was magnetized. I then tapped the clutch plate on the reverse rotation side (so if it caught, it would not come at me), and the clutch snapped shut immediately.

So that means that the clutch is worn enough that at higher temps, it expands enough that it cannot be pulled in.

Can the clutch be adjusted? Or, replaced without having to replace the compressor?

Any ideas are appreciated.

I hope everyone is well.

Darren
 

brcidd

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Take the clutch driver off and remove the thickest shim (if more than one) and re-install driver and be done-- I've done several this way.
 

Gus

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Never worked on a Trail Blazer clutch assembly......never heard of shims......most clutch adjustments are made just by tightening the nut, while holding the clutch assembly?

If it does have shims for gap adjustment, then it won't be the first time I've learned something new on this forum..... :)
 

NickD

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It works on a Honda or a Toyota, Gus, could be a minor bit of make and model confusion here. Even that A-6 never used shims, going way back to the late 50's.

Need a special puller/installer tool, at last count, have four different types, may need another, haven't checked that yet, GM changes that every five minutes. Really bent on this interference fit. Even a +/- 0.0001 can make a difference for a clutch plate that is way too tight or falls off. Wish they did use shims.
 

brcidd

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Your Trailblazer uses a Sanden compressor- thus it has shims- most every compressor made these days uses them..even Delphi finally went to them with their CVC compressor. I've been servicing compressor for 30 years- never heard of adjusting a clutch air gap by tightening the shaft nut-- heck it bottoms out on shaft shoulder by design on the GM press fit styles- and is only there to keep the slip fit shaft key in place-again by design. The nut was removed on late model R-4s and H-6 series 1998-2002 vintages. Things do change over time-- Just be careful when you wiggle the clutch driver off that the shim(s) don't fall out and lose them...
 

NickD

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For this era was J-33013-B for the clutch puller/installer tool. But the way GM has been outsourcing parts, no telling what you have, unless you look first.

Its been my experience going to my GM dealer with the year, make, model and engine, tell me to bring in the old part to see if they can match it up.
 

brcidd

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Just did a Sanden compressor on a 2004 full size pickup GM - remove one shim - now compressor works every time it is commanded on by the relay-- was intermittent at best..
 

NickD

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Finding a shim on a GM AC compressor is good reason to throw a party.

What time and where? :thx
 

clifclimer

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I have been following this thread about AC clutch not engaging on the 2002-2004 TB after everything gets warmed up( works fine for the first hour of operation). I have determined it to be the clutch. I checked the air gap it is at . 020. So I am assuming that the clutch needs replaced, the problem is that there are no clutches available either after market or at the dealer parts store. It appears that the compressor will have to be replaced. Is there a replacement clutch available??
 

clifclimer

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I have been following your post, trying to determine which is the most cost efficient path to take. In trouble shooting my 2004 Trail Blazer I discovered when my AC quits working after an hour of so of doing fine. The clutch does not engage, I checked the air gap and it is a snug 0. 020. I very carefully took a shortened broom stick from the front there is a small opening that I could bump the clutch and it would engage and work fine until I turned it off. Another thing I did very carefully I directed a stream of medium temperature water onto the clutch to cool it down and it engaged on it's own. I can not find a replacement clutch at after market or the dealer parts store. They only sell the compressor with the clutch attached. Am I gonna have to replace the whole unit??
Thanks
RIC
 

Roy

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Check here; http://www.autoacforum.com/ to see if Tim can get you the parts you need.
 

brcidd

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I just removed a shim on a 2002 Traiblazer compressor yesterday-- the clutch was pulling in slowly- one side then the other-it gave a double click upon each engagement- this too is a sign of a wide worn air gap--The owner had the same complaint as you folks-- no air after it warms up...Only trouble was that I had to remove fan and shroud to access front of compressor - then just remove the 14mm bolt from front of compressor, wiggle clutch driver out, then reach in with a magnet and pull out the shim- then re-install the clutch driver. I did not bother to measure air gap-- I only care than clutch does not rub when not engaged- and that pulley spins freely. Why buy a clutch when removing a shim works great? Do what you want- but I don't advise spending money you don't have to-- but you guys probably have plenty of money anyway.
 
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