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

[TURNA]

So you are saying just eliminate the relay and that plug since they are ECM related?

Hmmm replace a relay or replace a compressor????


I say 5 buxx relay

 

[hoffa65]

Hmmm replace a relay or replace a compressor????


I say 5 buxx relay

Tell me what this relay does after you removed the ECM,???
Nothing at all.
The low pressure switch protects the compressor not the relay.
Your jumper grounds the relay so it is always closed as long as the AC control is on.
Its not needed get rid of it.

 

[565bbchevy]

So looking at my pressure switch wiring I have 2 black wires the solid one ties into the ground for the blower motor and the other with a white stripe goes through a connector to one side of the compressor

 

[hoffa65]

So it sounds like on an 86 GM switched the ground side of the circuit. Older models switched the hot side
If thats the case the light green from the heater controls would go to compressor and the black from the compressor goes thru the LP switch then to a ground
I just pulled a harness from an 85 cutlass had the cutoff relay also. I can have a look in 2 hours after i get home.

 

[69hurstolds]

This post shows the electrical diagram for 1985 Olds VIN A, Y and 9. Maybe this could help. Or maybe it won't.
https://gbodyforum.com/threads/need-a-pic-please.73767/#post-705223

On top of that, here's what I got for 87 Olds CSM stuff. It may be what you're working with. I dunno. VIN 9 and Y were the same elect circuit in 87. Maybe in 86 as well?

 

[565bbchevy]

This post shows the electrical diagram for 1985 Olds VIN A, Y and 9. Maybe this could help. Or maybe it won't.

So do you know if I need this relay for the compressor? My 86' looks slightly different than this one pictured but is in the same spot

 

[565bbchevy]

yes

So when I tested this brown wire it has 12 volts when the AC is on did yours test the same?

 

[DRIVEN]

Unless I'm reading the diagram wrong, the ECM grounds the relay that completes the power circuit to the clutch. No ECM = no relay function.
I second bypassing the relay. Pressure cycling switch is your real control.
To answer your original question, that pressure (as shown on your gauge set) should get get the system to function. A rough rule of thumb on a resting system is 1# per degree F.
You can just jump the pressure cycling switch to test the rest of the circuit and clutch engagement.
Hope this helps.

 

[hoffa65]

from the print above you can remove the relay and splice together the light greens (wires 66) and the light green with black stripe (wire 966) at the relay plug. This will bypass the ECM's AC control function and the AC will cycle the clutch off the low pressure switch, like the older systems did before the ECM came into play. Discard the brown wire, after the greens are spliced the brown will have no power on it.

 

[fleming442]

Or, just ground the relay trigger since the ECM isn't providing a ground. Does the compressor black go straight to ground or through that crusty *ss relay? You could also cut the factory stuff out and replace it with an aftermarket relay and socket, too.