Okay, the weather finally got hot enough here to want to charge up my A/C Last year I drained and vacuumed it with the intention of converting it over. Well I found out that R-12 is only six bucks more per pound than R-134 this week, so I decided to not convert it, but recharge the system. After getting 2 pounds in it, the compressor never kicked in. The pressure switch is good. I jumped the terminal to make sure. I am getting power to the pressure switch, but not to the Compressor. I took the wire off the compressor and there is no power there with the A/C on. I swapped the fuel relay with the A/C relay to no avail. Any electrical gurus out there that may have a schematic of the system to point me in the right direction?

Thanks in advance...

Use a test light and see if you are getting power to the E terminal. The relay sends power from E to B and on to the clutch. First you need to find out which side is failing. The main power or the switching power to the clutch relay. Key on A/C on power goes through the A/C power relay and then on to the clutch relay.

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85 GT 4spd 2.8 1 yr blk
86 SE 4spd 2.8 2 yr blk
86 GT Auto 2.8 new to me.
87 SE 5spd Future 4.9 6yr

Yes, I have power going to the B from the E pin. I checked it at work, but only had a test light. I really wish I had my meter with me, I would have checked for an open between the terminal on at the compressor and the B pin at the relay. I am at home now, and checked for power, and there is 10 volts going across the relay at the E/B pins. I can not get under the car right now to check continuity. Is there anything else between the relay and the compressor that can interupt power?

Wiring diagrams to the whole car: http://www.euronet.nl/users/fo_elmo/wiring.htm

Thanks for the link to the wiring diagrams...

Anyone else. Any ideas would be appreciated. I will probably run a hot wire directly to the compressor to make sure the compressor is working

If you are showing power going to the B. Then every thing above that is ok. I take it you can hear the relay click then when you turn on the A/C. Is the plug at the compressor plugged in? Do you have power at the plug? Do you have ground? If all that checks OK You need a clutch. Why only 10 volts? You can have a short that shows 10 volts with no load and 0 with a load. Just a thought. B goes direct to the plug bofore the clutch.

Okay, today was sort of productive. I checked for power on the E/B pins this morning, and there was no power on the B side of the relay with the ignition on (car not running)and the A/C switch on, and the pressure switch jumped. I had power at the E, pin, but not on the B pin. Last night I had good power all the way around, so back to the drawing board. I grounded the C pin, and now I had power on the B pin. Then it dawned on me. The ECM is in the circuit, so if the car is not running, the ECM will not send ground thru the relay to power the clutch. After grounding the apprpriate pins, I had good power at the compressor. The compressor clutch solenoid is shot.

So can I change just the solenoid or the clutch without springing for a new compressor? If so how do I go about changing it. My worst nightmare is changing the compressor. I would much rather chase wires for several days.

the clutch can be serviced as a separate assembly. You need a few special tools to do it right. A clutch holder. A clutch puller and a often clutch press.

Autozone may have the needed tools in their loaner pool. You may be able to rent them.

If you don't use the right tools it becomes very easy to ruin the clutch and even the compressor.

The clutch, if you buy new, is almost as expensive as a complete compressor. You'll likely need to use salvage parts to fix it for any reasonable cost.

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Screamin' Yellow Zonkers... If it's Screaming and Yellow, I aint eatin it.

Well it looks like any way you shake it, I have to remove the compressor.

Thanks to all that offered advice. positve ratings for each.

are you sure you have ground at the plug on the compressor?

the KCFOG kit car was in the same setup only with 134.

and i discovered that the relay is not grounded without the car running myself just a few hours ago.

there is two connectors on the back of the compressor. the small one is the one that grounds the clutch and is a black wire going to the high pressure cut out switch.

jump the relay so you have power too the clutch without it running. and then ground the black wire.

the yellow wire is the low pressure cut out switch.

From the wiring diagram, it looks like the power to the compressor clutch returns to ground thru a high pressure cutout switch (at least for V6 cars). This could also be your problem. Check it out before dealing with the clutch.

quote Originally posted by buddycraigg: are you sure you have ground at the plug on the compressor? there is two connectors on the back of the compressor. the small one is the one that grounds the clutch and is a black wire going to the high pressure cut out switch. jump the relay so you have power too the clutch without it running. and then ground the black wire. the yellow wire is the low pressure cut out switch.

You know now you have me thinking... I did everything while under the car except check for ground at the compressor. When I was looking at the schematic this morning, I totally zoned the high pressure switch and the ground circuit out. I was so busy trying to figure out why I did not have power, that I forgot the cardinal rule... make sure you have good ground. I will have to wait until tomorrow to put the car back on a lift to chase that squirrel.

Thanks for the tip... There may be one shred of hope left I really do nt want to pull the compressor!

[This message has been edited by topcat (edited 05-10-2003).]

maybe the tread about the same problem i have may help.
https://www.fiero.nl/forum/Forum2/HTML/034967.html

I put the car up on a lift and grounded the high pressure cutoff switch and presto, the clutch kicked in. I let it run stay grounded for a couple of minutes, then connected everything back up, started the car, turned on the A/C and nice cool air started flowing from the vents.

Thanks to everyone that gave direction.

It paid off.