Can't get my compressor to come on even when I jump B1 and B4...

I took measurements at the relay socket and I get 2 12v terminals and the other 2 are 0v(not grounded)

I measured at the connector at the compressor and the green wire is getting its 12V's when I jumper the relay, but I am not getting a GROUND so it will not click.

I don't have any refrigerant in the system currently but the compressor should still click on/off if I jumper the relay socket correct?
Why am I not getting the ground to the Compressor????

Thanks

Cody

 

if ya dont have a ground it wont turn on or the low pressure switch is causin it not to come on as is no charge try jumpin the wires on the low pressure switch and see if ya have power and ground at commpressor if ya do and no action its a bad compressor

 

thanks for the input...
compressor is new but the pressure switch is not..I did check for 5v on the gray wire and grnd on the black, both check okay.

let me get this straight...

I want to confirm everything is working great before I fill with r134a so I guess I need to do the following?? correct me if I'm wrong...

key is in 'On' position
relay socket b1 and b4 jumpered
pressure switch is jumpered (red wire and gray wire)
does it matter what position the AC control switch is in???
the compressor should pull in if all the above is done right??

Thanks

 

the compressor wont pull a charge if car isnt runnin assuming u had the system vaccumed down at a shop or at home if ya have a a/c vacuum pump.if it is vaccuumed down car runnin a/c switch in car on start to fill system a/c commpressor should kick on after a few seconds assuming low pressure switch is good then fill to appropiate pressures

 

You cant charge to pressure, since pressure isn't a form of measurement. But that's a different issue.


The relay should work such as this:
Both pink wires hot with key on.
Dark green/white will have nothing yet.
Dark green will have a lower voltage ground.
With the engine running and AC on, as long as all conditions are met, the Dark green/White wire will have a ground signal. This drives the relay.

Black wire at the compressor is chassis ground.




With the connector unplugged (don't leave it plugged in to test), if you don't have ground on the black wire, trace it back. Or as long as you don't interfere with the in line diode at the compressor harness, you can run your own redundant ground instead.

 

Looking like its going to be my PCM not sending the ground...

Using Freescan the AC request is coming on when I turn on the AC but the AC clutch engage is not coming on in Freescan even with the pressure sensor bypassed...No codes at all either..

Going to pickup another OBD1 pcm and see what happens..I'm getting the 12Vs to the compressor and if I "bench test" the compressor the clutch engages..

Is it possible I could just reflash the PCM to fix it?

Cody

 

Like I said, if you are getting power, then you need to track the ground system.

 

Thanks guys, found the problem...It was an open in the ground near the diode...