Situation:
A/C compressor doesn't engage when turned on.

System has good pressure. I also tested the low pressure switch by jumping the 2 wires together. No luck.

Also, the logicon does not light up anymore when a/c is turned on either.

Questions:
How do I test the compressor? Can I jump it with 12v somehow?
How can I test the logicon? Does it sound dead because it doesn't light up?

Any other suggestions?

 

yup. The compressor has that one wire. Touch it to positive on the battery and it'll pull in. If that works and the clutch pulls in, there is a a/c relay located in front of the radiator, biased off centerline of the car towards the left side. Bad news is I forgot which relay it is. There is two, maybe three there.

I bet someone knows right off the top of their head. Which is the a/c relay.

EDIT: I'm looking at a 88 online manual and the relay seems to be the third from the left, in front of the radiator. It should have a B/W wire, a L/B wire, a R/W and L/W wire. The B/W goes from the relay to the single connector at the compressor. The R/Y should have 12v on it when the a/c is turned on. That one pulls the relay in. The L/B should supply the B/W with 12v when the relay pulls in. This is out of a 88 online manual.

If you don't have 12v on the L/B wire, go to the fuse box and look at the bottom row, second fuse from the left. A 10 amp fuse

 

Yes, you can hit the compressor with 12 volts direct just o see if it clutch kicks in. You don't need the car running to do this. I'm surprised that if you jumped the low pressure switch, you didn't activate the compressor. When ckeching, make sure there is voltage @ the switch, then when you jump it, with a/c button on, see if you have any voltage @ compressor.
This is a start.

 

Turbonuts reply makes more sense than mine. With the a/c switch on, you should have had 12v on one of the two wires at the pressure switch. If there is none there, then the path to wellness lies other than my first reply. The path heads back into the passengers side of the car where a couple of relays hang out on the bottom of the blower housing.

 

Hailers-You do have a way with words.
This is to be taken as a compliment.

 

I thought the A/C relay was located at the nose of the car on the drives side with all of the other relays.
There is a relay at the blower motor as well?

 

CBLAKE3....Attached is a 87 schematic. It shows a red/yellow wire thats involved in pulling in the ac relay thats up front. Theres also a LW wire that goes to the ECU.

Anyway, the R/L wire goes to a mess located on, above, near, around the blower motor. I never could make sense out of what does what in that big square called BLOWER UNIT. See what I was talking about??????

I need to look at a 89 or 90 manual. Maybe they will make more sense to me.

Turbonut.......when your right, your right, and you were right as right can get.

 

oh, the schematic:

 

I think the way the a/c relay works is that there is 12v at the LW wire from the ECU, pin 1E. Then if the blower fan is on to put a ground on the relay, the a/c relay up front pulls in which in turn puts 12v on the compressor.

 

Hey, thanks for all of your help Hailers. I took a look at it last night when I got home. I am getting 12V to the compressor. So I guess I will need to replace the compressor.