Tried searching. Cant find anything related to my issue. Ive tried charging it and the system wont take any freon. The conpressor will engage if I directly apply 12 volts to it via the plug. It seems to hold a vacuum. But like I said I cant get it to cycle. I can see on the passenger side by the firewall is a pressure switch. Is there a common issue or maybe this switch is bad? Is there a way to test this sensor?
Any help appreciated.

Its a 2000 3.4 2 wheel drive sr5
And for the record I have my auto hvac license but this one has me stumped...

The easy way would be to jump the pressure cutoff switch and see if it runs. I wrote a bit about this awhile ago. Check it out and if you need any other help just holler.

Please tell me my AC compressors not toast

good luck.

In case you need it I found this here in Tucson.

2001 Toyota 4Runner A/C Compressor

The compressor is fine. The clutch engages and it cycles if I bypass the switch and everything and just run power straight to the battery. If I bypass the switch nothing happens at all though. My method of getting 12 volts to the clutch is by shoving A wire into the compressor clutch connector and running it around to the battery. But in my case a paperclip in the switch Connector did not work.
Thats why im wondering if there is another switch thats mayne not obvious or if theres another problem area I should look into

The AC controls on the dash come to mind. Or a relay in the junction box.

Is the AC pressure switch two wire or three?

Do you have manual or automatic controls?

Toyota is fond of using an A/C amplifier, which is VITAL to operation. What year is your truck? There is much to look at!

My link to the on-line EWD is not working right now. You don't say if you have manual or digital control but SR5 I'm guessing manual. I'm going by my paper '99 EWD.

Clutch engagement requires:

1. 12V+ from 10A A/C fuse, goes to...
2. A/C switch, goes to...
3. Closed circuit from pressure switch, goes to T1 blue/white on A/C amplifier.
4. Ground from Blower switch at T4 black/white on A/C amp.
5. Engine speed signal from ECM
6. Absence of low evaporator temp signal from A/C Thermister at evaporator.

Turn-on signal to clutch is 12V+ on T9 from A/C amp black/yellow wire.



To start with, I would check if you have 12V+ at blue/white wire at pressure switch. No means fuse or or A/C switch. If yes, then confirm 12V+ at T1. Then check #4 above. No ground means blower switch or it's connections. If all good, then it's 5 or 6 which are more complicated, but I bet it's 1-4.

If you have digital A/C, post back and I'll revise. Here is the link to the EWD, maybe it's working when you read this--it does go down sometimes. I hope it's not dead for good.

http://tacoma.site40.net/4Runner_96-...i/057acman.pdf

EDIT: The link came back, but it's messed up. It says manual A/C, but it's the digital A/C diagram as far as I can tell, since it shows servo motors, etc. If my description matches what you have, I can scan my diagrams if you need them.

Of course you post 1 minute after I did, I was on my way out the door for a MTB ride, but I think you got it covered @TheDurk

I do have 12v at the pressure switch plug. It is the manual ac controller. And the plug is a 2 wire plug. I havent have time to check the other plug yet since I work alot.

Does 12v leave the pressure switch?

Idk because I cant get the compressor to cycle so I cant add any freon so its just empty right now. If I bypass the switch with a paperclip there is power beyond the switch but still no cycling. For the sake of getting this thing figured out and to avoid having to buy a switch right now ive been bypassing it just so I know that things are fine beyond the switch as well and obviously theres a problem somewhere.

OK, NOW I am confused, in your original post you said nothing happened when you bypassed the switch, now you say there is power at the switch, and beyond if you bypass. That would indicate the switch is bad since it IS what creates the cycling. Unless you are calling engaging the clutch "cycling".

So now you are left with 4-6 on my list. #7 would be a fried A/C amplifier.

Basicaly what im saying is that its between the switch and the actual clutch itself. Because even if I bypass the switch the clutch still wont engage. What I did to engage the clutch was run a wire from the positive terminal on the battery all the way around to the plug on the compressor itself and it does engage. I wont have time until friday to check out the other steps

I've dealt with the blinking AC light. Replaced the relay. Adjusted the Freon charge, all with what ended up being very temporary results.

Today I found the cause for my AC clutch failing to kick in. In my attempts to diagnose the problem, I pulled the plug for the AC clutch in order to jump the connection with a hot wire. Since the connector is facing down, I was having trouble with my test lead falling out. I pulled the connector away from the base where it's mounted to the AC compressor to make it easier to see what I was doing.
After pulling the connector from the mount, I was able to look inside the connector and look directly at the "blade" inside the connector. This is when I realize the blade was bent over a little. I straightened the blade and reconnected the plug. The compressor clutch now works.

Point is, if you're having trouble diagnosing a none working AC clutch, take a close look at the inside of that plug for a bent blade.