AC Compressor - Dead?

[1990C4S]

My son's '02 Jetta AC compressor is engaging and not grinding/making terrible noises. But no cold air.

Low and high pressures are correct when resting, 100-110 psi both sides.

With AC on I see liquid bubbling in the bottom third of the glass on my gauges, but the pressures barely change.

I'm guessing the compressor has died?

[hcoles]

I suggest if your AC compressor is making any sort of "bad" noise is to stop turning it (AC off).
You might avoid blowing chunks throughout the system.

[1990C4S]

There is no bad noise. It is quiet.

A couple of possible scenarios, clutch is engaged but slipping?

Still low on freon, although 100 psi resting would indicate not.

Compressor seals are gone internally.

[rusnak]

If low and high pressures are the same, then it sounds as if the expansion valve is clogged. It also sounds as if you are low on charge.

[1990C4S]

Originally Posted by rusnak

If low and high pressures are the same, then it sounds as if the expansion valve is clogged. It also sounds as if you are low on charge.

Is 100 psi low? I was thinking that was about right...but I could easily be wrong.

At this point on the old car I could just add some more...

[asphaltgambler]

What is the low/ high side readings @900 RPM's?

[1990C4S]

^^^^ Roughly 100 psi on high and low when idling, low starts to drop a bit, then goes right back to 100 ish.

[asphaltgambler]

So it seems the compressor/ internal valving has failed. It's not generating pressure or suction at all.

[JackDidley]

I think the low side should be around 40 at idle. Low and high should not be near the same.

[1990C4S]

Originally Posted by asphaltgambler

So it seems the compressor/ internal valving has failed. It's not generating pressure or suction at all.

Seems that way...I guess it's toast.

[1990C4S]

Originally Posted by JackDidley

I think the low side should be around 40 at idle. Low and high should not be near the same.

That should be at idle, but when compressing they should be more like 40 psi low and 150-250 high...

[JackDidley]

Originally Posted by 1990C4S

That should be at idle, but when compressing they should be more like 40 psi low and 150-250 high...

Yes, you seem to have equalized. Probably time for a compressor.

[asphaltgambler]

I would safely rule out anything else in the system as nothing is going on with the low / high side

[mattdavis11]

Check the air gap at the compressor clutch, if too great, remove the outer hub, remove shim in hub, or on shaft(if needed). The air gap should be about the thickness of a business card.

However, my bet is on refrigerant control valve on the back of the compressor. Same pressure = Equilibrium. Looks just the same as a stuck open expansion valve. Most of the time you see expansion valves pull the low into a vacuum when bad. I've only seen a couple go the other way.


Refrigerant control valve.

[1990C4S]

Yea, I was wondering about the clutch not really engaging. I think I will get down and feel the compressor. If it's rotating inside I should be able to feel it.

[mattdavis11]

What size motor? Diesel? Gas? Gl? Hard to ID the Sanden compressor with out more info.

[mattdavis11]

Originally Posted by 1990C4S

Yea, I was wondering about the clutch not really engaging. I think I will get down and feel the compressor. If it's rotating inside I should be able to feel it.

If the valve, (if it has one) is sticking open, you may not. Rotate the hub, see what it does. It will feel like a somewhat like free spinner if it has a valve, and want to pound low pressure vapor into a high pressure vapor if no refrigerant control valve.

[vash]

when my compressor quit, or so I thought; it was more of an electrical problem. I was checking fuses, relays and grounds. I changed a few things and it all got cold again. think this is an option?

[1990C4S]

Originally Posted by mattdavis11

What size motor? Diesel? Gas? Gl? Hard to ID the Sanden compressor with out more info.

2.0T, but it's the same compressor as my TDI. It's the cheap on/off style. VW also has a climate control variable compressor.

[mattdavis11]

Maybe. Not likely though as the compressor does engage.