Why won't my a/c work?!

[gpking]

Uhh, guys...


Friday I noticed my a/c was blowing hot, so I decided to do some troubleshooting.
I didn't have to look far before I noticed my compressor clutch wasn't engaging because it is completely gone.
I had to do a double take because I couldn't believe my eyes. It is really just gone.
I have no idea if it exploded or fell off, but it's anyone's guess as to where it is right now.

Non-serviceable, non-schmervishable.
This weekend I'll probably hit the pick-a-part and swipe a compressor clutch.
Any idea on the torque specs? Ideally, I'd like to prevent this from happening again.

Has anyone ever seen anything like this?

 

[Sparky]

Uhhh That's a new one!

 

[Mooseman]

Looks like the nut fell off allowing the clutch plate to go on vacation. Like you said, just grab one from a junker. Try it on without the shim first. If you still have a gap, call it good.

 

[littleblazer]

Torque spec is tight enough so that doesn't happen again. Probably like 20. Use some lock tite if the lock but is kinda worn.

 

[Tiggerr]

Wow!! That's a new one on me lol!! Just pulled my shim today hope mine doesn't get pissed and go on vacation lol

 

[gpking]

Shoot. Does anyone know what size the nut is?
I obviously have nothing to base it off of, and that detail is left out of all the write-ups.

AutoZone had a 9mm nut listed under a/c compressor components but had a banner that said "Does Not Fit Your Vehicle". It didn't look like the correct nut either.

 

[littleblazer]

The nut on mine was 14mm

 

[m.mcmillen]

I have a couple of old compressors at the shop off of trailblazers. When I get back later today I will check and see what size nut you need to get (not the wrench size).

Did you find a clutch plate yet? I might have one that is still good. I just changed a compressor that the clutch bearing failed.

 

[Sparky]

If you swipe a clutch plate from a pick-n-pull, swipe the nut too.

 

[gpking]

The nut on mine was 14mm

Interesting, thanks. I'll definitely take like 8-16mm sockets just in case.

Did you find a clutch plate yet? I might have one that is still good. I just changed a compressor that the clutch bearing failed.

Nah, the weather has been cool all week. I'm going to the pick-a-part Saturday. They do a nationwide 40% off sale for Memorial Day weekend (https://www.lkqpickyourpart.com/locations/).
That means $12 for a compressor clutch.

If you swipe a clutch plate from a pick-n-pull, swipe the nut too.

That's the plan. Plan B is a combination of zip-ties and old chewing gum.
(I already have the muffler heat shield held on with zip-ties).

 

[gpking]

Well, it wasn't the clutch.
Shim or no shim it wouldn't lock up, so the last suspect is the coil. And I ain't replacing that.
I had to take the clutch off just so I don't burn it up by mistake. What a waste of a trip.

 

[Mooseman]

Well that sucks. What's your plan then?

 

[budwich]

"what's your plan?" get a meter and see what happening in "electrical land".

 

[gpking]

I have no doubt the coil has some internal short causing it to be weak. It's the only remaining suspect. The compressor is being commanded to engage, but it's just not strong enough to completely lock up the clutch. It barely grips at idle, as soon as I start revving the smoke starts pouring out from it slipping so much.

I had the bearing catastrophically fail last year, and I put a lot of miles in last Fall, so I have no doubt heat might have killed the coil.

If the coil overheated, the insulation on the coil wires - which likely is nothing more than an enamel coating like motor windings use - can melt in spots to short part of the coil and make its magnetic attraction weakened when energized. So technically it could still "work" but not with full attraction, which could lead to a weak engagement and possibly clutch slippage. At higher temperatures the wire expands a little bit (like all materials do when warmed up) and it is possible that the expansion causes an internal short or circuit breakage. I've seen windings get damaged like that before.

http://gmtnation.com/forums/threads...-parts-advice-2002-envoy-slt.2990/#post-66237

For now, we'll just leave the clutch off and live without a/c.
I don't have the time or motivation to replace the coil with a junkyard find which may or may not have the same problem.
None of my friends have an a/c machine for personal use right now, so replacing the compressor is out of the question.
And I'm not about to pay a shop to do it, that's not in the budget.

Btw, last year I contacted the company which was once the company behind eBay seller "Air Parts" out of Florida that used to rebuild our clutches. I got thrown around on the phone before they connected me to who I'm assuming was a tech, and he said he can still do it, but the price (especially including shipping a compressor to Florida) was far too impractical to justify.

 

[gpking]

Bumpdate: My buddy had an a/c machine collecting dust in the back of his garage, so we cleaned it off and swapped in a new OE compressor. I enjoyed frigid air for about a month.
Now, I turn on my a/c, it will run for 5 minutes tops, then the compressor will disengage and not engage again until it sits for some time with the engine off.

Scanning; the recirc, rear defrost, and a/c request parameters are not responding even though the respective controller lights will illuminate (and rear defrost works, I can hear the DDM/PDM click). The a/c permission parameter is set to "withheld".

I have yet to do any electronic troubleshooting because nobody seems to be able to explain what this issue means. So it looks like I'll just be throwing more parts at it until it works again for another 3 weeks then stops.
I'll update when I finally figure out what it is.

 

[Sparky]

I'd be checking pressures. At least with my home AC unit, it would kick off after a couple minutes due to an overpressure situation (unit was over filled slightly).

If pressures look ok on the gauges, then I'd be checking the switches for failures to see if one of those is kicking off when it shouldn't.

 

[gpking]

I forgot to update this thread! I don't know what the solution was, but knock on wood, I had cold air the rest of the summer.

The problem was either that:
1) I originally charged the a/c system at 1am when it was below 50 degrees and it put too much r-134a in due to some pressure science-y stuff I don't fully understand (and the automatic a/c machine didn't correct for). Re-charging when it was over 70 degrees fixed.
or
2) I had some other weird electrical issues so I cleaned & re-seated some under-hood connectors that solved a bunch of issues including this one.

Regardless, my new compressor functions fine now.