TXjeepTJ

iTrader: (8)

Hi All,

I am working on a 2008 Pontiac G8 GT. The ac is not blowing cold. I hooked gauges up to it, and the high and low side pressures match, which means the compressor isn't doing anything.

I pulled the wiring for the AC compressor and confirmed it is getting voltage when AC is requested on (12v). I even hear a very faint 'click' at the compressor whenever I push the ac button on (engine off, the click is VERY faint. Nothing like the non-VD compressors when the clutch engages).

Is this faint click normal? or should it be a more aggressive click like non-VD compressors do when the clutch engages? Do I just need a new compressor?

Thanks!

Kawboom

It should be beyond obvious when the compressor clutch engages, the tiny click you hear is probably the relay.

TXjeepTJ

iTrader: (8)

Well, for anyone in the future needs information, the 'weak' click is NORMAL for a variable displacement AC Compressor. What the faint click is, is the actuation of the slow moving pin within the compressor beginning to move. This is the pin that pushes on the wash plate that allows for the variable displacement function.

I applied 12v directly to a new compressor and began to spin the front hub by hand to feel if there was a resistance. At about the 5 second mark, I could definitely feel it compressing when turning it. So it take a little bit, but the time you're waiting is the time the pin is moving in the compressor to actually start the compression function.

I did the same procedure on the old compressor, but I never felt any resistance/compression forming - so 100% bad compressor. I'm pretty sure the pin is stuck and will not move.

I've read/watched videos from pro-mechanics saying you need a Pulse Width modulation device to activate the compressor to see if it is working... I don't think that is true. Applying 12v makes the compressor go 'full on' mode.. if you wanted to see the ranges of the compressors compression function, then you'd need a PWM device, but for the everyday mechanic / to prove the compressor is bad, 12v directly!

G Atsma

Future FYI- It's SWASH plate, not wash plate.....
Just so ya know....

TXjeepTJ

iTrader: (8)

oops