Chevy & GMC Vans

The 2000 Astro van I bought, has had some little problems, that Ive asked about in this forum, and I've gotten some great advice.
So now my next, and hopefully last (at least for now) question, concerns the air conditioning.
While running, I turned the air on, and the compressor didn't kick on.
So I bought 4 cans of R-134a, and proceeded to charge up the ac.
When I put the gauge on it, it was charged in the range it is supposed to be.
So now I'm looking why the compressor clutch won't kick in.
I've checked the 2 fuses under the hood, as well as the relay. All is fine under there.
The fuse under the dash is good too.
I unplugged the compressor, and checked for voltage. With the key on, and the AC on, I got 12 plus volts.
would the clutch be bad?
I'm pretty handy with tools, but not too smart on diagnosing the AC area.
I'm looking for some direction here, as to what I should be looking for.
I've gotten some great advice before, so I'm looking to get some great help with this one.
Thanks to all who have helped me, and when I can, I return answers to others questions. ](*,)

did the compressor work when you put in the R134 ? There is a pressure switch that you can unplug and jump the 2 connectors to see if the clutch will engage. Typically you need to have the compressor running to add the refrigerant

I just spent $900 on my AC system, first time since I bought the '98 new, now with 174k.

Look and see if there is oil/grease around the compressor cases, as if it's been leaking out of the compressor, this is how mine looked and ultimately would not hold freon. If you do have to replace it, there are many other items you should do at the same time. When through replacing hard parts and adding freon, it's about $600+. I paid for labor too, thus my $900 price tag. UGH!

I hope this is not your outcome as well.

What I would do is to place a couple jumpers on the clutch and see if it pulls in from the battery directly. After that you will know where to go. If it doesn't pull in, replace the clutch. If it does pull in we gotta look at controls.

That is what I was wondering, jumping the clutch, to see if it would pull in.
I checked 3 fuses. One under the dash, and 2 under the hood.
I also pulled the relay out, while the van was running, and it had an audible click to it, as I plugged it back in.
As for the compressor to be running,while checking the freon level...... Well, I've had to add freon before, (this being some of my other vehicles) and when I hook up the gauge, it is reading way low, so I had to add freon, before the clutch would kick in.
I will see if I have voltage at the plug in to the compressor, and I will jumper a couple wires to the clutch, from the battery, to see if the clutch kicks in. I've had to replace the clutch before, but had trouble finding the sweet spot, where the clutch would engage, and not howl, when kicked off.
I will also jumper the pressure switch to see if the clutch will engage.
I should be able to do this with the key on, AC on, and jumper the plug in, I'm hoping.....

Since your control relay 'clicks', I would simply check the circuit at the compressor clutch connector. Just put a test light between the 2 terminals on the connector for the clutch while the engine is running & the a/c is turned on. There will be a black ground wire & a dark green power wire on this connector. If your test light illuminates, then the control circuit is working. If this is ok, then plug the compressor clutch back in and give the front of the clutch a smack while the engine is running. If it engages now, the air gap of the clutch is too big or the coil is too weak.

I have read an article on the clutch replacement, on "ask.com".
A person can get just the clutch assembly, and change it.
In it, if I remember correctly, that if a person is changing the coil, if the ac is charged, there is a possibility that the pressure could blow out a seal or something behind the magnet, after removing a snap ring(?).
Is this something I should be concerned about? If so, how risky is it to do, while the ac is charged?
I'm betting that the clutch needs replacing, not that I look at it, it's rusty.

You can remove the clutch plate, clutch hub & clutch coil from the a/c compressor with out any fear of blowing off the a/c charge. Replacement of the clutch components does require the removal of 1 large snap ring which secures the clutch hub onto the front of the compressor.

However, contemplating this repair at this point is a little premature as you have not sufficiently confirmed the issue - at least not in my professional opinion from what I have read. You indicated in your original post that you had 12 volts at the clutch coil plug. Voltage is not always a good indicator of sufficient power (amperage). Is this voltage enough to light a light bulb? or head light? If yes, then the control circuit is working good. Next, you may have an air gap issue. If the clutch gap is too large, the magnetic pull of the clutch acting on the clutch plate may be reduced to the point of not working. The clutch plate is held away from the clutch hub via spring steel links & this may be too much tension for the clutch to overcome. If you 'assist' the clutch in its efforts to pull in the plate with a simple smack & the clutch engages, then I would suggest that your air gap warrants a closer look.

I did some extensive troubleshooting on the van.
I've followed the schematic through, anc checked at various spots for voltage, to see if there was a wire broken, etc.
I've unhooked the clutch, and when I put 12 volts to it, it pulled in.
It wasn't until I got into the control switch, that I stumbled across the problem.
Just for sh**s and giggles, I had an extra control from my junkyard excursions, that I thought, why not try.
That did the trick.
Apparently, there is an electrical switch behind the round vacume plug in, that must also control where the air/heat is supposed to go.
So now I have air, and I'm damn happy.
Thanks to all who answered my post. You all gave good advice, and I'm glad there are so many great people who are willing to help when and however they can.

Glad you got it fixed. No AC really sucks. Especially here in Florida.

No AC is not so bad...

It's the Chin Music from my passengers that I cannot stand.

Congrats on the fix.

those are the cheap and easy repairs I don't mind.

It is nice to bounce ideas off one another, it helps so much.

Well done! =D>
Everyone can do with someone to bounce ideas off at some point.