The AC isn't working and we really felt it this past week with unusually high temps in the upper 80s to 90 degrees.

I checked the fuse and it looked new.

The AC compressor looks to have had or has a leak. It's less than three years old, installed by the previous owner. There's evidence of green dye on it. I bought a can of RF-134A and when I hooked it up, it barely took any. So it seems that there's enough refrigerant in it.

Anyone have any ideas or suggestions where to look next?

Thanks,
Bob

 

Find an AC shop , that green looks like anti-freeze.

 

That green is leak detector dye that goes in with the refrigerant. Common place to leak with re manufactured compressors mine did the same thing on my 79...once all the charge escaped I actually just moved the snap ring around a bit & the leak stopped.

 

http://catalog.fmsiinc.com/item/pag-...-kit/item-2754

I use this on my top ups on systems with tiny leaks! works fine.

 

Well, dumb question: if there's still a substantial amount of RF-134a in the system, wouldn't I be getting at least some cooling when I turn it on? BTW, I think the refill can mentioned an anti-leak additive.

Thanks,

Bob

 

Where you have the four washers on the compressor bolt is incorrect. There is a spacer that goes between the compressor and the bracket. If you lost the spacer, put the washers behing the bracket. The way you have the bolt installed could be putting a strain on the compressor and the bracket.

 

Does the compressor run ?

 

that leak has probably been there a while long enough to leave the dye & not enough 134 in the system left to cool.

 

But that's what I don't understand. As I mentioned above, I hooked up a refill can to the blue cap fitting (hope that was the right one) and only a little 134a transferred into the compressor. That leads me to believe that there's a lot of refrigerant present. I looked at the can last night and it has oil and a leak additive. I wonder if it's worth discharging whatever refrigerant is left and then trying to refill it?

And I believe you are right re the dye being old, as nothing else has leaked out of that cap since I've had the car.

The belt is apparently turning the compressor pulley.

Re the missing spacer, I don't have it as the AC was installed by the previous owner. I'll be removing the washers and placing them per the gazman's observation between the compressor and bracket. But, just eyeballing that move seems to put the compressor out of alignment with the belt. We'll see today.

Also, the compressor looks new but maybe re-manufactured also look new? I'm going to email the previous owner and ask him about this. The only reason he installed a new AC was to boost the appraisal rating he had done in 2007.

Thanks for all the suggestions and comments so far.

 

Does the compressor clutch engage ?
You mentioned you checked the fuse.
The compressor needs to run to pull 134 in from your can.

 

Due to the location and amount it certainly does look like antifreeze, nothing to do with the a/c.
The green might be dye, and to see it clearly you should use a uv light source. Normally impossible to see green without the light.
If you want to check for a FRESH leak, clean all the a/c areas with degreaser and rinse off, operate the system for a while a check for dye.
A minimal amount around the front seal is normal, but it should be years before needing additional refrigerant.
Check to make sure the center shaft of the compressor is turning, not just the pulley.


The only way to diagnose is to use gauges and using a "leak sealer" will create problems down the road, for reasons I won't go into.

 

Here's what I did:

1) hooked up an AC gauge to the compressor, and it read "fully charged".

2) started the engine, and had my wife turn the AC switch to Max.

3) I looked at the silver-colored shaft on the front center of the compressor. If that's what you were referring to, I couldn't see it turning.

4) Also noticed no drop in idle RPM when she switched the AC on.

5) What I did hear was a click on the engine firewall, near where the green wire from the compressor is located. It sounded like a relay or switch?

6) No cold air whatsoever from the system.

Should I assume it's an electrical problem that's preventing the clutch from engaging?

Here's a pic of the front of the compressor. Is the shiny silver section the center shaft you mentioned? Just want to make sure I'm on the same page!

 

The shiny center of the shaft as well as the triangle shaped part of the clutch will spin when it engages.

I was recently working on a forum members 78 ac. I discovered that whoever did his r12 to r134a conversion left the shrader valve in the low side fitting and then put on a 90 deg adapter like the one on yours with a shrader valve core in it as well. It was impossible to read the low side pressure because the inner shrader vavle core was not pushed open by my gauge hose connector.
Check and see if you have power to either side of the pressure switch when the ac is on. It's best to use gauges on the hi and low side for accuracy when troubleshooting. The green wire going to the compressor is coming from the pressure switch. If you have power on the one side of the switch but not to the compressor clutch wire, you may have a bad switch, or you may have low charge and a false low side reading due to two shrader valve cores in the low side.

 

If I remember correctly, there is a switch that controls the a/c clutch that will not allow the clutch to engage if the refregerant is low. Try bypassing that switch with a jumper and turn on the a/c. If the clutch engages at the compressor and it starts getting cold inside, my bet would be that switch is defective.

 

You have to get the compressor to kick on to draw refrigerant into it. Follow that green wire coming off the top of the compressor. It should be going into a plug with another wire. That is your low presssure cutoff switch. If she's low on refrigerant, that switch will prevent the compressor from coming on. Unplug the two wires from the switch. Take a paper clip, piece of wire, anything will work, and connect the two wires together. That will turn on the compressor. You're just bypassing the low pressure switch. Then hook your can of refrigerant up and if it's low, the compressor will draw it into the system.

 

Thanks to all for the suggestions and info.

Here's what I did this morning:

1) Started the engine and turned the AC on to max.

2) I tried to trace the dark green wire from the compressor to a switch, after opening up the wiring harness.

3) It seemed to go to the switch in the photo below, which is located just a short distance behind the AC. I thought that this was the logical choice as when I opened the harness some more just upstream from this switch, I didn't see the same color green wire.

3) I unplugged the wires from the switch and put a wire jumper inside the plug. The clutch didn't engage. Thought I might not have made good contact with the plug prongs, so I jammed a paper clip into the two prongs. Nothing.

4) So, it seems I didn't find the right switch. Also, I have a GM Corvette Shop Manual, and when I checked the AC wiring diagram, it shows the green wire going to the comp switch but also a tan wire, too. The other wire in the switch I just bypassed has a light blue wire.

Following the harness further upstream, it disappears behind the distributor and I couldn't find a switch on the other side of the engine or firewall.

Other than the fact that I'm NOT a mechanic and unfamiliar with the Vette engine so far (after a month), I welcome any further help! :o

But, the advice given so far has increased my knowledge of the AC, refrigerant, and the clutch. Every little bit helps!

Bob

 

If memory serves me correctly, the tan wire you found changes to green at the hpressure switch.

You can take a jump wire directly to the positive battery to test the compressor clutch.

 

The part in your picture is the a/c thermostat. Hook it back up like it was. Look to the right of your compressor, just under the lip of the inner right fender. There is a small round switch with two wires going into it. That's the low pressure switch. It's maybe five inches from the compressor. Unplug the two wires, and connect them together with a piece of wire and the compressor should kick on. I told you wrong in my first post. The green wire coming off the compressor does go to the a/c thermostat, not the cutoff switch. The two wires plugged into the low pressure cut off switch are your hot wire and the other thermostat wire.

 

Here's the pressure switch you want to jumper the wires for.
To the right of the pic, black and silver under the hose....

You won't get a correct pressure reading unless the compressor is running.

 

A picture is worth a thousand words. As KapsSA said, you can't determine how much refrigerant you have until you get the compressor going. Once it kicks on, put a pressure guage on it and see what you have. I think it should read about 35-40 psi when fully charged. If you get the compressor to kick on, then it probably just needs charging. If you had to replace the compressor and dryer/accumulator, it's not that hard. We can walk you through it. Good luck.
KC