I hate to add more work to our volunteers,BUT, I have a problem with my a/c ! I found the post broken that holds the blend door lever in place and repaired that. Thought that may be the cure ! Wrong, the a/c still quits ,randomly. It usually comes on and cools nicely for sometimes a hundred miles or more or it may cool for a couple of miles and then just quit cooling. If you leave it alone it will probably resume cooling. Really hard to make heads or tails of it ! Thanks ahead for any help.
Wayne

When the cooling stops is the blower fan still running? Just asking because I've had folks say that the system stopped cooling when it was actually the blower motor cutting out.

When the cooling stops. look and see if the compressor is still engaged.
-Is it is, look at the limes where they go into the evaporator case. If they're frosted up, the evaporator may be icing over.
-If the comp is not engaged, tap the face of the clutch with a screwdriver handle. If it engages, the clutch gap is too wide.If it doesn't engage, you may be looking at an electrical issue.

Thanks for the response ! The blower motor does continue to run and I will check the clutch and lines for freezup. Thanks for the suggestions and have a great weekend !

Well now the clutch won't engage at all. I pulled the connector to the clutch and I only get about 2-3 volts. There is continuity in the clutch itself, checking across the two connector blades. If this is a simple mag.coil clutch why can't I run a new set of wires from the coil connector,one to ground and one to a 12V source ? That would at least tell me for sure that the clutch was ok.There is .030 gap and when I put the feeler gauge in it comes out with some pretty black gook . I assume this is normal with the clutch doing its thing. Thks

Ok. Now go to the accumulator near the evaporator case. Disconnect the cycling switch and see if there is power to the connector. If so, jumper the connector and the clutch should engage.
If there is no power, the switch on the control head may have a problem.
If there is power and jumping the connector engages the clutch, the switch is bad or you've lost the refrigerant charge. Since it works good when it works, the switch would be the likely culprit.

Is the black goo oily? If so, the shaft seal on the compressor is probably leaking. If it's dry, it's just dust from the clutch.

Its oily so i guess a seal is in the future.

Its oily so i guess a seal is in the future.

At 25 years, I'd seriously consider a good reman compressor. Those R4s were'nt GM best effort to begin with.
They often have wear in the front housing that lets the shaft move around. New seals usually don't last very long.
Also, .030 is about the wear limit before the clutch starts to slip. You can close the gap, but it's still pretty worn.
25 year old R4, worn clutch, leaky shaft seal. It's time, IMHO.:dontknow:

First things first, though. Lets figure out your electrical problem. Then you can enjoy the AC until it stops cooling due to the leak.

lsrx101, Thanks so much for the trouble shooting ,the connection at the cycle switch is the culprit ! It appears that the internal spade connectors are just "tired ". I wonder if the plug is available as a replacement or just use crimp on spade connectors ? Again,my thanks for your using your time and talent for all of our benefit. Thanks, Wayne

You're welcome Wayne. Glad to help.
That connector is available as a repair part, I believe.

Isrx101, Now that was perfect. Just saying.. Dale

lsrx101, Just for future reference,is that switch replaceable as some are without pulling the freon out ? Thanks

Thanks Dale.

Yes, there is a schrader valve under the switch. Just unscrew the old one and screw on the new one.

lsrx101, Well here I go again ! I repaired/cleaned the connector on the cycle switch ,made a jumper for the steering cut-out switch and everything was working great !! Notice,WAS ! I had to install new valve stem seals and after I got it all back together everything was working great,EXCEPT, the dash vents! I'm getting plenty of air on the floor but not the dash! I have been all over my re-install of everything and can't find a thing. I am going to order the two vac switches anyway but they were not touched during the seal job. Any ideas ? This ahead of time for your consideration. WP

Did you get the vacuum reservoir hooked back up?

Did you get the vacuum reservoir hooked back up?

...and correctly?
It's easy to reverse the lines on the reservoir. There is a check valve in the reservoir and if connected backward, you will have no vacuum to the control head.

Wayne, please describe in detail how you repaired the post on the blend door. Was it necessary to remove the dash or just the glove box? What did you use for a new post and how was it attached, glued? etc. etc. Obviously, I have the same problem and my fix was to disconnect the heater hoses and insert a pipe fitting to recirculate the water. That works until I need heat or defroster!

I didn't detach the reservoir lines ,but I will check them again . The post repair is going to be tough to do unless you have a very small aircraft air angle drill for close quarters. Hang loose and when I get the "proper" repair bracket made I will send you one. It is basically going to be a metal bracket with a post made into it and the bracket will be screwed to the housing side. I will try to get it done next month. If you want to PM me in about three weeks to rattle my cage I will hopefully have it done. WP

I just went out and checked to make sure the vac line was indeed still hooked up,and it was ! If the engine is run and then shut down,shouldn't there be some vacuum stored in the vac reservoir ?

I just went out and checked to make sure the vac line was indeed still hooked up,and it was ! If the engine is run and then shut down,shouldn't there be some vacuum stored in the vac reservoir ?

Yes, There should be residual vacuum, due to the check valve in the reservoir.
Maybe you crossed some vacuum lines? The reservoir should be connected to a manifold vacuum source. It has high vacuum at idle. You can feel it well with your finger on the source.

Thats what i thought . I'll be checking it out in a few minutes and I guess I have pulled one loose or cracked one. I'm getting ready to replace every vac hose anyway. They look pretty good but at least I'll have a good ,known age of them then. THKS

The vacuum Res. Is holding vacuum,pulling by mouth, and the check valve is holding, there is no vacuum line going to the heater valve .I have searched and do not find one. I feel I am still overlooking something as the dash vents were working perfectly before the valve stem replacement. I have found nothing out of the ordinary except for no line to the heater valve. I may have one hiding somewhere and if so I will find it,sooner or later.Where can I get a schematic for the vacuum system? Thks

HEH HEH HEH !! You can run but ya can't hide,for too long that is ! GOT IT and just as suspected,it was a hard 1/8 line pulled out of the flex rubber line !The rubber tube had flipped up under the rain trough behind the distributor.I ran a temp. vac. line to the line and when the vents worked I knew the area I had to concentrate on. I am going to replace all of the hard nylon 1/8" tubes with new tubes,of the correct color code of course. These Els are getting to the point that rubber and nylon tubes are needing help ,in most cases.AGAIN,thanks for the feedback ! Its really a pleasant surprise to find so many guys,and ladies, that are willing to help others. God Bless you all ! Wayne