How much refrigerant is needed to kick the ac clutch on for an empty system?

[565bbchevy]

So my AC system has all new everything on my 86' Regal, it holds just under 30 lbs of vacuum and after pulling vacuum for 45 minutes I went to add refrigerant to the low side and it took it very slow maybe 15 minutes and didn't even take a full 12 oz can and this is about where the gauges were when I shut it off with the clutch never kicking on.

 

[oldsofb]

Should be somewhere around 25 psi. I would start checking elect functions (jump the comp clutch and see if it energizes, then move on to the low press switch and relay)

Hutch

 

[hoffa65]

first check for 12vdc at the low pressure switch, one side should have 12v to ground with heater controls set on AC. if you have 12v to ground on one side Ohm out the pressure switch should have low to no resistance with that pressure in the system, if low plug back in and check for 12vdc to ground at the compressor plug, if 12v ohm out clutch

 

[565bbchevy]

first check for 12vdc at the low pressure switch

There was no power at the 2 prong harness for the switch but I did pull this relay and look at it, does power for the switch go through this relay?

 

[TURNA]

Yes compressor power goes through the relay

 

[565bbchevy]

I cleaned up the harness and relay connections I am getting 12 volts from the 2 lower right terminals which have green wires and there is a black wire and a green with black stripe that appears to go to the compressor.
I plugged the relay back in but still no power to the pressure switch terminals, the relay could be bad or still have a bad connection.

 

[TURNA]

Shake the relay hear anything?

Or just jump it

If you have a power probe that helps alot

 

[565bbchevy]

So where is this plug supposed to be plugged in at? It is tied into the wiring for the compressor and relay

 

[hoffa65]

are you still running the ECM?

 

[565bbchevy]

are you still running the ECM?

Not running the ECM but it is still plugged in but the wires are cut but somewhat accessible.
Is that what the plug is for something for the ECM?