A/C pressure switch location?

[Jbbishop2]

Can someone point me to the location of the a/c pressure switch in an '88 4WD van? I have the '87 manual but the diagram for the 4WD dual system doesn't show the pressure switch, and I haven't spotted it on the system yet.

Really, the location of the connector where you can use a jumper to get the compressor clutch to engage would be the ticket.

Thanks,
John

[originalkwyjibo]

Did you find it yet? On one of my 88's it's right in front of the radiator. Two lines extend from the bottom side of the condensors up in front of the radiator and the switch is mounted between them. I'll try to look at my other van and post a pic later today if you need it.

[Jbbishop2]

Thanks very much for the tip. I haven't found it yet, have to look in the spot you describe when I get home from work this evening.

This finally moved me to buy a 1988 service manual off eBay, which hasn't arrived yet.

[originalkwyjibo]

First pic is from passenger side with receiver/dryer in the right foreground. The flashlight beam is focused on the wires for the upper switch. There is actually two of them. One on top of the pipe and one below.

I circled there location in the diagram in my manual. I suspect the '87 manual has the same pic as my '88 manual but I don't know why they didn't label the pressure switch in the 4WD diagram.

[Jbbishop2]

Great picture, thanks! I found mine just where you said it would be:


I don't know why there are two of them; more study required.
There are two connectors, one white one between the switches, and one where they go into the harness, Do you know if I can just put a jumper in the connector between the switches, or is it the other one? They're easier to see than to reach, from below for me, anyway.

Thanks again. I couldn't get to it for a few days, had to marry off my oldest boy in between.

[originalkwyjibo]

I stuck a jumper in the white connector on mine the day I took the pic but it didn't do anything. Then I remembered this van doesn't have an a/c belt on it. I need to do a/c work on both of mine so I'll hopefully be revisiting this soon. You can unbolt the a/c condenser with two bolts on either side and one at the rear nearer to the radiator. At that point the whole carrier frame will hinge down on the center two mounts and the flexible rubber portion of the hoses. You can also finagle it up and out of the two center mounts and pull it down further. This was how I gained enough access to get two hands on the connector to safely separate it as well as to remove the fans and hose the dirt out of everything a few years ago. I glanced at the wiring schematic briefly but hadn't determined the purpose of the dual pressure switches before my lunch break ended the day I was messing with it. I have a camping trailer needing rot repair this weekend that is taking priority over the vans at the moment. We'll have to keep each other updated as we go.

[Jbbishop2]

This is a bit late, but...
Before this, the a/c wouldn't come on, compressor wouldn't kick on, and when I checked there was no pressure or refrigerant in the system.

Before trying to find the pressure switch I'd changed the ports to the fittings for R134a and pulled a vacuum on the system, which held overnight. I put in some oil by letting it get sucked in by the vacuum on the system, but it was only about half the total required per the specs. Since I hadn't drained the compressor oil I hoped this was sufficient.

I got the compressor going by pulling the engine cover to be able to see the compressor clutch wire, then jumping 12V over to it after starting the motor and turning on all the a/c buttons and setting the fans to high. I then added the R134a. When it had enough pressure, after the first 600 g or so, I hooked the compressor clutch wire back up and it ran as it was supposed to while I added more R134a. The total added was 1182 g by weighing the cans before and after. The spec for the dual system is 1300 g so I figured that was close enough to get on with, and the a/c was blowing cold in the front (not in the back, I'm not sure why, maybe the magnetic valve for the rear evaporator wasn't opening).

I live in coastal northern California, not much need for a/c around here, but I visit family in Bakersfield. The Valley is miserable hot in the summer (especially this summer) and while I grew up there I left for a reason, and I'm too old to be that uncomfortable just because. I turned on the a/c a few times on local trips to be sure it would come on, but turned it off once I felt it working.

First trip to Bakersfield after getting it working, first week of June, I turned it on upon reaching the Valley, around 100 degrees outside, and it was working. Turned it off to see how much difference it made in the indicated engine temp (not much, maybe the width of the needle on the gauge lower), then turned it on again. No cold air.

Turned off the switch and checked it when I got to Bakersfield. At idle the compressor would not kick in (I think my idle-up switch isn't working), but when I revved it a bit the clutch engaged and it made a horrible squealing noise. I figure it's either the belt squealing on the pulley because the compressor seized, or the compressor is turning and making that noise, which is just as bad. So I turned it off and sweated the rest of the trip. I haven't had the heart to get back into it. Plus, the hose of death went this week so I've been working on that.