Back in the old days, simply turning on the A/C kicked it on and it would stay on, regardless...

But it's not like that anymore, the stupid thing does what it wants, does anyone know how to override the mechanism so that it stays on when I want it to, even if it involves installing a switch or whatever...

 

There is a switch on top of the acumulator/ reciever dryer. I believe it is a green 2 pin connector. Unplug it and put a jumper wire in it.

 

^^^ correct.. your clutch might be goign if its acting like that.. or the wiring from the clutch to the switch may be shorted any arcing.. wouldnt hurt to take a gander at everything while your in there

 

If you run a switch to directly control the AC clutch, bad things can happen. The least of which is evaporator freeze-up, which means that ice can form and block air flow, making the system cool well for a while but stop working suddenly and not work again until you let the ice melt. The worst of which is that the high side's pressure may go through the roof and something will literally explode.

That said, a direct control switch can give you better AC performance if you use it in moderation and you're willing to accept the risks.

 

Yes, I understand the risks, I am aware I could ruin the entire A/C system among other things, I just wanted an override for troubleshooting and some cold A/C in the meantime.

I found this plug on top of a canister by the passenger side front of the firewall... Doesn't look green but upon pulling it there was corrosion on the connector, also jumping it did nothing but reconnecting it did, I'm currently looking for a paper clip so I can clean it out lol...

I have gauges, so the charge is fine, I suspect it is a problem of a slight mix of PAG and Ester oils, but just not sure and wanted to eliminate some other causes.

Anyway, I did find a paper clip, after cleaning it and jumping it, that was it. Strangely it now cuts off when I reconnect it, I got a feeling somewhere therein lies my problem, the system cools good otherwise, any ideas?

 

maybe that switch is bad, that switch is supposed to shut the compressor off when the lowside pressure drops below a certain point (can't remeber the spec though[:@])

 

Those switches do go bad. Of course clean the connectors first, and if that doesn't work and you want to replace the switch, I think there is a Schrader valve underneath it that will prevent explosive discharge of the system when you remove it. Disclaimer: You should verify that yours has one before pulling it.

Also, the switches are usually adjustable, and sometimes even if they aren't actually out of adjustment, turning the adjustment screw can clean it up and make it work like new again. Look under the electrical connector for a slotted screw, and jiggle it back and forth a quarter turn at a time and see if that helps. Also, as you may have guessed, you can crank the screw down to get better AC performance instead of using a jumper wire.

As for a jumper wire, I've had success running a wire via a dash-mounted switch directly to the AC compressor clutch relay, but this was on a GM... I haven't tried it on my truck and probably won't since the AC works very well.

 

Don't add any overrides to that switch. It's a pressure cut out switch that is there to protect the compressor in case of low pressure and as mentioned, to monitor evap. temps. It sounds like you are low on refrigerant. It's also possible the switch is bad. You have gauges, what numbers are we looking at (first line of attack). The switch should kick the compressor on at ~45psi and off at ~22psi. Can you get any results jumpering the switch? If so, what do the gauges read?
Then there's the whole PAG/Ester thing. Why were they mixed in this 134 system? PAG ONLY here.
Then, you jump the CONNECTOR. The switch is underneath and threads into the low pressure line. Did you unscrew it and check for corrosion there or just at the connector? Also, replace the O ring under the switch as these very often leak.
Hope this helps.
WC
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your clutch is going if it is acting like that, happened to me, i just bypassed it, i don't need my a/c plus i got less strain on my engine, so im getting better mpg