2000 SL1 not cooling
 

Alright so about a year ago my ac (clutch) would turn every once in a while...low on refrigerant...well eventually it quite turning and I have been without ac since. Well I just recently put refrigerant in...and it still is not working. I can turn the clutch with my hand though. I checked the relay and it is fine...I am used to seeing two wires going to the compressor, yet on mine I only have one...a green one...not sure if that is a ground...anyways I was hoping someone could inform me on what is the problem...or have any ideas!
Thanks

Have someone put a set of A/C gauges on the system while your car is shut off. Read and write down both the high and low pressure readings. Now, start the car, and turn the A/C to high and max cooling. Read and write down the gauge readings again.

Put those readings here on the forum, and we will be able to help some more

ok I did that...they are the same pressure
Low side (off and on) 71 psi, r134 is 21
High side (off and on) 75 psi, r134 is 22

So obviously the compressor is not kicking on...do you know how to jumper the compressor out...to see if it will come on? Cause there is only one wire going to it...a green one...

Ok I shall let you tell me what to do next....thanks

Not trying to threadjack -- I just added R134a to my 95 SC2 as refrigerant was low since last fall.....(figured low pressure switch had been tripped). Had the A/C clutch kick in for about 3 min, then disengaged on its own. Did not cool while engaged.....Added a bit more refrigerant, no dice. A/C clutch will not kick back in, even after letting compressor physically cool down....

These compressors have a high temp cutoff switch, yes? If so, where is it?

Per snellenj -- how do you test the functionality of the compressor (meaning how do you distinguish between clutch engagement issues)and actual compressor functionality issues)?,......or is it that if the clutch is not being drawn in to engage, the compressor is toast......pls advise as east coast is heating up

The green wire is the clutch engagement wire (+12v). There is a thermal cutout located on the compressor mounting bracket. Trace the green wire back to it. If the thermal cutout has failed, you will not have +12v on the green wire even though you have the A/C turned on.

And you will not have 12V on the clutch engagement wire if you are too low on refrigerant either, since the low pressure switch will inhibit the A/C request line from going high and actuating the relay, yes?

Pretty sure I have enough refrigerant in there.....

Also sounds like a quick check with the battery to the green wire will separate the live form the dead......as long as there is enough refrigerant AND the thermal cutout has not cut out

Thanks OA!!! I'll go test and post the results

ok thanks I will go check!

Also, please let me remind you both -- by 'outboarding' this power to the A/C clutch, you are bypassing ALL of the safety and interlock switches. DO NOT RUN THE COMPRESSOR LIKE THIS FOR ANY APPRECIABLE LENGTH OF TIME !!!

Understood, sir. The green wire goes through a connector, then through a "solid fitting" (I cannot come up with another way to describe this..), then another wire comes out through the same solid fitting, to a detachable connector, which then appears to go to the A/C clutch.

I have continuity from the connector to the clutch. What I do not have is +12 V on green wire -- it appears to be about +0.4V DC---which I assume is actually telling me the A/C diode is intact (which I had already checked anyway). I'm starting to think that the issue is with the A/C request signal and the relay, though I had swapped the relay with a known good one and no-dice.

But the lack of cooling when it did run was worrisome too....unfortunately I do not have a set of gauges right now -- I'm looking at low side pressure only.....

But I will do a quick jumper to the battery to ensure the A/C clutch engages.....

Thanks OA!

Well, jumpered the clutch enable wiring to the battery---clutch tries to kick in right away --kinda makes a grinding noise while engaged (if it is fully engaged) -- again, no cooling taking place.....

So, taken with my explanation above
1)the A/C clutch will only engage when directly wired to 12V
2)does this mean the clutch itself may be bad and not necessarily the compressor?
3)i ask 2) above yet I fear that a high or low pressure switch is inhibiting the A/C request signal from enabling the relay through the PCM....

OA, what's the next step for me?