How to test Low pressure AC switch?

[ronpapworth]

I'm trying to help diagnose my friends 1996 4cyl Camry Air Conditioning problem. I want to jump the low/high pressure switch at the receiver but it has 4 wires, not the standard 2 I have seen. 2 blue and 2 green. Does anyone know which wires I should be jumping to see if the compressor is good? I don't want to add 20 bucks worth of r134a if the compressor is shot. That was the diagnosis when he took it to a shop last year, but you know how shops always want to replace good parts for good $...

[xtremeskier97]

[ronpapworth]

Yeah, I saw that in my searching, but I think it is just a test of the switch and fan. I was thinking you could put a wire between 2 of the 4 and force the compressor to kick on (if it's not dead). maybe not?

[ShawnM]

If you just want to see if the compressor works, jump the terminals at the compressor control relay thats in the relay box on the left fender. You should also be able to turn the outer section of the clutch by hand with the engine off, unless of course the compressor is totally locked up.

[ronpapworth]

Thanks very much Shawn! Thats exactly what I needed to know. So if the outer part of the compressor (thats the magnet clucth I am assuming) will not spin then just that part needs to be replaced, right? I have read that it is a pretty easy and cheap fix...

[xtremeskier97]

Oh..so you didnt need to test the pressure switch, you need to test the compressor clutch. You can do it the way mentioned above, or you can test it another way. You disconnect the wire connector at the compressor and put a lead to the battery to see if the clutch engages. I did that to mine while I was replacing all the o-rings in the system. Now whether it engages AND spins...Im not sure. Ill check that before I get it charged.

[ronpapworth]

Ok,
So after checking the 10amp fuse I decided just to throw some r134a into it. The ac button is now blinking, I can hear the engine start to idle up when you hit the ac button, But I am not hearing the compressor clutch kick in and of course Im not getting cold air. I also have about 50 psi on the low side with the cheap gauge I am using so I think Im a little full.

How do I jump the compressor to see if the magnetic clutch is bad? Looking at the compressor for sale on EBay below, is the clutch the inner circle in the pulley? Doesn't look like any AC clutch I have ever seen! Where do I connect the positive wire on the compressor to test the clutch? The grey plug I am assuming? And if I do it at the relay, which slots do i jump? I think relays typically have 4 blades? Or is there another relay in the bank that I could put in the AC clutch replay spot?

http://cgi.ebay.com/ebaymotors/toyot...mZ150258381294

[ronpapworth]

Oh, and he says it is a 97 as well, is that gen 4?
I read that the relays on these things blow out all the time too. I can probably just do a relay swap?

[xtremeskier97]

I cant answer your questions until I get home and look at my manual to know for SURE...but my 2 cents...an A/C compressor is definitely one thing on a car that I would NEVER buy used. You can get good deals on new ones on ebay. I did with my 92 accord.

[ronpapworth]

Thanks,
yeah, I was just posting that pic to show what looks like magnetic clutch. I see the new ones are just under 200 bucks...

So that inner ring on the compressor pulley should spin (if I can wedge my hand in there) without the engine/compressor running? It just looks like a metal ring, my guess is that the actual moving magnet part is under the pulley itself around the shaft of the compressor...

[xtremeskier97]

You can see what the clutch consists of in the second picture. What you are referring to as the 'clutch' is actually the pressure plate.

[ronpapworth]

Cool. I went looking for that manual again last night but could not find it. So I probably put 12v to the wire coming off the stator im guessing to test the operation of the clutch.

The guy left work early yesterday, so I still need to try swapping relays first...