AC Not Cold - Did Search - Need Your Wisdom

[RamJet]

Okay G8 Brethren, and Sisthren, I need to tap your wisdom.

I wasn't sure where to put this, but here looked good.

AC started blowing not cold yesterday out of the blue. No noises, no drama, just noticed it was humid in the car. Temp reads fine, display thinks its controlling everything, no codes, interior fan works, radiator fans work as they should, heater works.



After searching both boards, I checked the belt - it's on, checked the fuses - all good, and no damage to the hard lines.



I took it to a reputable shop, they squeezed me in at the end of the day.

The Tech-canic said the system wasn't low, the pressure in the system was great, but that my clutch was shot on my compressor as it wouldn't fully engage, he watched it try to. He said that if it did, it would snap the drive belt and leave me stranded. I explained that the G8 compressor didn't have a clutch like a normal AC compressor, and that it had it's own drive belt, so I would be okay in that scenario.



So my question to you all is, does it sound like a bad compressor, or just a compressor getting a bad or no signal?



I'll check the wife's to see what it looks like, but would definitely like to hear your thoughts.



Thanks in advance.

[THE Adam V]

Have you hooked manifold gauges up to the system to verify high and low side pressures? Did your mechanic actually drain and recharge the system (he should have if he checked system level)

I believe our cars do have a compressor clutch, and are not variable displacement comrpessors. If you want to verify this, have someone sit in the car and press the a/c button on and off. You will hear the clutch engage *click noise* when the turn a/c on and another click as the clutch disengages when the hit the button again.

[RamJet]

He said he checked the pressures, that's all I have on that one. I don't think he drained it, they didn't charge me.

And just to be clear, he's a mechanic, I'm my mechanic. I was just looking for a place that had a good reputation as I haven't dealt with AC stuff before. I was hoping for better, but I guess he did his best.

From the searches I did, it seems our AC compressor is a variable displacement job. I can't say with authority that it is for sure. I'll have to try your test.
Do you think the compressor needs to be replaced? I just wanted to bounce it off of you guys before spending my hard-earned cash.

Thank you for taking time to respond, much appreciated.

[THE Adam V]

It's hard to diagnose an a/c issue without at least seeing the pressures on the gauges. I wouldn't go replacing the compressor without knowing for sure. If you have time, take it to the dealer to get diagnosed if you are not confident.

If it does end up being the compressor, I would replace the tensioner with the updated one while you are down there.

Have the system recharged using the label and make sure they add compressor oil

[LDM]

I believe our cars do have a compressor clutch,

They don't.

and are not variable displacement comrpessors.

They are.

I was telling my dad about it one day and he'd never seen one like that before so I showed him pretty much the same test you describe. The compressor is always spinning. Also, from the service manual:

The Denso compressor can match the air conditioning demand under all conditions without cycling. The basic compressor mechanism is a variable angle swash-plate with 6 axially oriented cylinders. The compressor has a pumping capacity of 160 cc.

The electronic control valve is installed in the compressor rear head. The swash-plate angle of the compressor and the resultant compressor displacement, are determined by the compressor crankcase to suction pressure differential which is governed by the control valve.

When the A/C capacity demand is low, the crankcase pressure behind the pistons is equal to the pressure in front of the pistons. This forces the swash plate to change its angle to towards vertical which reduces the stroke of the pistons and reduces the output of the compressor to approximately 4 cc. The evaporator cooling load is reduced, ambient temperature or blower fan speed is reduced and therefore, the suction pressure is reduced until it reaches the control point. To reach the control point, the electronic control valve assembly allows discharge pressure to bleed past the control valve ball valve seat and into the compressor crankcase. This crankcase pressure acts as an opposing force behind the compressor pistons to cause the swash plate to change its angle towards vertical and therefore, reduce piston stroke.

When the A/C capacity demand is high, the crankcase pressure behind the pistons is less than the pressure in front of the pistons. This forces the swash plate to change its angle away from vertical which increase the stroke of the pistons. The compressor will then have a corresponding increase in its displacement.

To the OP, I wish I could be of some help but I'm not sure what the problem could be.

[RamJet]

Len, all input is appreciated.
It's starting to sound like the control valve isn't doing it's job, but I have a sneaking suspicion that it isn't sold separately.

I do wish that the shop had been able to give me a print out, or even a sticky note with the pressures written on it. I'd call today, but I don't imagine that he's remember what the numbers were, he sees a lot of cars each day.
A friend here at work has a gauge, but it only measures the low side. I guess that would still tell me something.
Good call on the improved tensioner, I was thinking the same thing.

Keep 'em coming, it all helps.

[THE Adam V]

I wasn't sure but thank you for the clarification Len!

[RamJet]

Okay, so I had both cars in the air, and after fiddling with the pressure switch connector, I noticed that the bottom front of my compressor had this odd looking bright yellow oil seemingly coming from behind the pulley (see pic).
The wife's is clean as a whistle, and hers works.
So I've ordered a new compressor, but will also try to put new seals on my old one for the future.
Once again, I'll keep you posted.

Now on to crushed strut mount bushings...

[BuildItYourSelf]

O yeah. Bad seals.

I have new factory bushings and bearings I'm trying to get rid of if you don't want upgraded ones.
Pm my if your interested.

[RamJet]

Thanks, BuildIt, but I jumped on the Kollar deal. Thank you for the offer, though.