Sorry, just saw your message spanobain1234. On my '85, this is how I bypassed my A/C low pressure switch:
http://www.4crawler.com/4x4/CheapTri...ne_Pix/20.html
Not sure if that's what you are referring to. There's also the A/C idle amplifier, that has an "RPM" knob that sets the low idle cutout RPM and then there's the A/C idle-up Vacuum Switching Valve (VSV) and adjustment knob on the valve cover:
http://www.4crawler.com/4x4/CheapTri...ine_Pix/7.html
You need to get those set properly for the A/C to work. You need the cut-out RPM set a bit below the normal idle speed and the idle-up adjustment set to speed the idle up a but when the A/C is on. The idea of these two settings is the low idle cutout stops the A/C if the engine is bogging down at idle, but the idle-up setting makes sure the idle speed jumps up a bit when the A/C is on.