I've been following the AC repair posts and taking notes towards fixing my own AC problem.
So far, nothing has been quite representative of my situation. I think the cause of my problem may be different than the usual suspects.

This is a long post, but I want to describe what I HAVE tried and tested.

Here goes:

When I bought the car, the clutch wire was severed about 5 inches from the compressor. It looked like maybe the compressor was installed with the wire pinched to the bracket or block.
The remaining wire from the harness connector to the compressor is gone. I ran a new line from the remaning clutch wire to plug back into the harness. I applied external 12 volts to the new wire and the clutch draws a couple of amps and engages. so far, so good.

I cannot get the clutch 12v supply from the harness to work.

A/c fuse is good.

L/P switch must be bypassed for the elect. fan to come on, so I am assuming I'm low on freon.

There is 12v at the low pressure switch. The small wire "leaving" the switch is at ground potential. This ground potential causes the 12v at the pressure switch to dissapear when the 2 wires are connected, jumping the l/p switch.

Freeze switch passes 12v fine.

I have removed the control unit and cleaned and "flossed" the blue relay contacts. 12v passes through the relay fine. I momentarily bypassed the relay, no help.

I have studied the manuals and current flow diagrams. There is a Electro air valve in the circuit with the clutch and the l/p switch. A reference point should be pin 9 on the 14 pin connector near the jump terminal. The valve appears to have the ability to bring the circiut to ground potential. I have been unable to find this valve. (see my electro valve post and Wally's response). I want to test the circuit with the valve unplugged.

The manual shows what an 84 valve looks like, but it is different on an 86. I thought I found it on the air intake, just behind the oil filler, but the wiring does not appear to connect to the circuit with the clutch and l/p switch.

I have not seen mention of this valve in Nicole's thread about A/C problems, nor on the pirtle or Greg Nichols sites. I'm trying to find out if the valve exists, and if it could be the cause of the circuit going to go to ground.


I am also concerned that if the A/C was switched on sometime in this car's past while the clutch wire was pinched to ground, that there may be a burn in the harness or the electro valve. Maybe the missing wire from the connector to the clutch burned? Who knows.


I'm confused as to why, when the l/p switch is jumped, the electric fan comes on. That would indicate that the circuit for the l/p switch is O.K. and if it is, why no supply to the clutch?

According to the current and wiring diagrams the electro valve, l/p switch and clutch are on the same line.

The wires for the l/p switch appear to be the original harnessed wires, but the supply is the proper size and color code, the other wire is thinner and the wrong color, but appears to be original. I would have expected both wires to be the same thickness.


I also want to verify that the clutch supply connecor is the brown single spade connector leaving the harness at the top of the passenger timing belt cover? is that the one?

I'm stuck.

Any ideas?

Thanks,
Greg

 

Sounds as if you are using the fan switch on top of the receiver/dryer, rather than the low pressure switch down on the side of the receiver/dryer. Kneel down and look thru the grille at the receiver/dryer to find the low pressure switch.

 

Thanks Wally. That would explain part of the confusion.

Do you think I have found the electro air valve as described in my post? (on air intake behind oil filler cap)

I'll update what occurs tonight when I dive back into it again.

 

Thanks to Wally for getting me on the right track.
Everything is connected properly.

I still need to (hopefully) just top off the R-12.
L/P switch need to be bypassed for the clutch to engage, but that is all that's left to do.

Thanks again,
Greg