need help with a/c

[TurboCajun]

I just installed a know working compressor in my car, first time putting a/c since I converted to 87 setup. I got everything in and hooked up, started the car to make sure the belt would stay on. turned the car off, key on, a/c switch on and jumped the dryer connector and the compressor does not come on. What would be the next thing to look for? Relay, wiring,

[daveismissing]

Is the high pressure cut out on the compressor wired up?

[TurboCajun]

yes, the little two prong plug

[Steve Wood]

gonna assume you checked the ac fuse and the ecm-sol fuse in the fuse block.

Jump the dryer connector with the key on and the AC lever on Max.  Check to see if you power at that point.  If you do, go to the AC relay on the inner fender.  Check for power on the pink/black wire and the light blue wire going to the relay and the dark green wire coming out of the relay that goes to the compressor.

then check at the compressor clutch connector to see if you still have power at that point.

If you do, rig a jumper from the black wire on the connector to a good ground and see if the clutch clicks and locks up.

[TurboCajun]

I have power at the  three but not the solid green wires at the relay

[Steve Wood]

that would be the wire going to the compressor clutch so my guess is that the ac relay is bad

[TurboCajun]

ok Steve I am a little confused, after a i try a spare relay and also a new one I still do not get power to the green wire. if i put 12v to the green wire at the connector it kicks the clutch in. hard to believe that I have three bad relays in hand. the three other wire have 12v with relay plugged in, two wire have 12v with relay out, and one wire 12v when I disconnect the jumper from the pressure switch connector.    how can all the wires have 12v if working correct, Where is the ground in all of this that makes the relay activate?

[TurboCajun]

also I was looking at a diagram and one wire goes to a brake switch, would removing the power master brake system have anything to do with this?

[Steve Wood]

No...and I don't recall that wire...maybe that was on a hot air car?

Here are the two diagrams for an ic car

[TurboCajun]

ok the green/yellow wire should get ground from the ECM, its not for some reason, when I use my test light hooked to the ground on battery and touch the green/yellow wire it activates the relay which in turns activates the clutch. so the ECM is not sending the signal for ground.

[TurboCajun]

I also checked the wire from ECM to connector for the relay, it has continuity. SO it has to be something to do with the ECM

[Steve Wood]

It should be grounded as you say by the ecm to trigger the relay.

It's possible the ecm is faulty but I would go under the dash and find A2 on the ecm and run a jumper to the relay to see if the clutch gets activated like it should before I changed the ecm

http://www.vortexbuicks-etc.com/ecmwiring.htm

A2 is on the smaller connector

[TurboCajun]

well Steve I feel dumb, but looking at that diagram I noticed that the KEY ON position holds the 12v, and the RUN position gives two different voltages, meaning the you have to have the engine running. unlike the 85 setup. Thanks for all your help, and I am sorry to put you thru my long brain teasing operator problems.
   cheers my friend

[Steve Wood]

Long as you got it working, who cares?

If you don't have a copy of the shop manual, download that free one that was just mentioned.  I live and die with the wiring diagrams and troubleshootin g tips