A/C Diagnostics, Electrical

[sdb999]

Compressor clutch isn't cutting on. I've got decent pressure (40/150) and about a 20 degree drop at the vent outlet. I would think it's not the pressure switch but want to start there. Where is the pressure switch? Where is the A/C Compressor Relay (if there is one)? Probably idle kick-up issues too but I'll start with the compressor.
Thanks, S.

1987 22re, manual.

 

[flyinhawaiian01]

Grab the pdf manual from links in this forum, it should point to all those parts you're looking for.

Question... If your clutch isn't "cutting on", then how are you getting a 20 degree drop at the vents?

 

[sdb999]

Jumped compressor to charge a completely dry system. Found the pdf download, good call.
Thanks, S.

 

[txcrawl]

Previous owner of my 88 ran a switch straight to the compressor. He couldn't tell me why it was done. I know crap about a/c and electrical but did run across a part under the dash during my searches called the A/C Amplifier that has something to do with controlling when the compressor kicks on/off. I've just been using the switch and haven't looked further into the issue yet.

 

[sdb999]

Yep, rain ruined my mx plans so tomorrow it's: fuse, amplifier, pressure switch, relay and everything else. Just have to step through the fsm diagnostic. Great advice here on all fronts. I'll let you know.

 

[sdb999]

low pressure switch looks good. Previous owner removed vsv completely so.....no idle up. Funny though with vacuum connected to idle up valve the screw would not adjust idle so I'm thinking it's bad. So I've got some parts to source.

 

[Kencart]

A/C switch issue

Nevermind, I'm dumb. With the dash apart (for a different project) I was plugging my switch into the rear defrost switch. That's a relief. I'll tell my wife I fixed it I recently bought this 92 v6 4x4 auto. I'm trying to get the AC working. I charged it, and it runs cold if I jump 12v from 3 to 7 in the amp, bypassing the switches. I tested the other components, and found #4 to the switch isn't getting power. I tested the switch which (turned on but unplugged/unpowered) has continuity from 5 to 6 but not 4 to 6. Two questions: the manual doesn't mention if it needs power to get cont from 4 to 6 but I would think it does. Is that the case? Thats easy enough for me to test, so my real question is why my harness for the switch looks like it's pinned wrong. It has wires going into every port except 5 (including 2). It seems maybe the one in 2 should be in 5? Do I have the wrong switch? I don't get it. I also don't know the history of the truck.
Any insight would be appreciated. I plan to power the switch to test it then assuming it works, I need to reconfigure the wiring harness I guess.

*update.
Super confused.
Black and yellow from #4 in amp has no cont to b&y in the switch (which is #5 in the map but actually goes to 6)
The b&y at the switch has 12v with the switch on, off, and unplugged. What am I missing? According to the map, there is one connection between the two which tests fine. Where is that voltage coming from? And by the way if I jump both ends of the b&y the AC comes on (when the switch is on, off, and unplugged. )