Thread: What happened to your D3/D4 today?

I would think the PRV,if on the high side would normally open at huge pressure,something like 400PSi or higher.

Getting to those sorts of pressures would be a pretty good effort,running 134a, for a system that is operating normally.

No doubt the valve is faulty is it appears to be venting at a lower pressure.

Some PRV's on refrigeration also open at a predetermined temperature,but these generally dont reset.

Originally Posted by Eric SDV6SE

Possibly DJ, but if its worn out, wouldn't all the refrigerant vent to atmosphere? Or is it bypassing internally?

A few things, the vent to atmosphere is extremely rare, I made a compressor do it one day by accident.. Wow. Never again.
Most systems use a high pressure switch to control the clutch circuit therefore it won't go bang.

Your issue is likely the same as mine, as the compressor wears out.. It fills the oil with "grey death" which is a mix of alloy and oil. A thick paste that clogs up condensers, filters etc.
The compressor is a variable displacement type and is controlled by the ECM. The ECM controls whether it's a big compressor or a little compressor by changing the pumping stroke, once filled with grey death, the compressor gets stuck on "little pump" mode and can't pump enough gas for the heat load.

Originally Posted by josh.huber

A few things, the vent to atmosphere is extremely rare, I made a compressor do it one day by accident.. Wow. Never again.
Most systems use a high pressure switch to control the clutch circuit therefore it won't go bang.

Your issue is likely the same as mine, as the compressor wears out.. It fills the oil with "grey death" which is a mix of alloy and oil. A thick paste that clogs up condensers, filters etc.
The compressor is a variable displacement type and is controlled by the ECM. The ECM controls whether it's a big compressor or a little compressor by changing the pumping stroke, once filled with grey death, the compressor gets stuck on "little pump" mode and can't pump enough gas for the heat load.

Thanks for putting that in plain English mate

Originally Posted by josh.huber

A few things, the vent to atmosphere is extremely rare, I made a compressor do it one day by accident.. Wow. Never again.
Most systems use a high pressure switch to control the clutch circuit therefore it won't go bang.

Your issue is likely the same as mine, as the compressor wears out.. It fills the oil with "grey death" which is a mix of alloy and oil. A thick paste that clogs up condensers, filters etc.
The compressor is a variable displacement type and is controlled by the ECM. The ECM controls whether it's a big compressor or a little compressor by changing the pumping stroke, once filled with grey death, the compressor gets stuck on "little pump" mode and can't pump enough gas for the heat load.

And you 100% have to change the condenser and flush out the rest of the system as I understand it?

This is where DIY becomes tricky as how do you do the mechanical removal of AC pump then drive the car to get it flushed since the accessory belt is now off and then complete the job?

Are their mobile guys who will come to you?

Originally Posted by josh.huber

Probably froze, defrosted, then went back to dumping it's guts. The change out isn't that bad.. Few beers.. You'll be right

Around 10secs between a sudden stop of venting and then restarted before finishing of the rest of the system

Originally Posted by PerthDisco

And you 100% have to change the condenser and flush out the rest of the system as I understand it?

This is where DIY becomes tricky as how do you do the mechanical removal of AC pump then drive the car to get it flushed since the accessory belt is now off and then complete the job?

Are their mobile guys who will come to you?

I'm lucky I have a ticket. The flushing gear is cheap. Changing condenser is best practice. But I didn't. I just back flushed it twice. You can change the compressor, flush it install the new compressor then drive to get it done or have a mobile guy come round. There are plenty around.. I only use genuine orings these days. It's just easier. Your not supposed to flush through a tx valve. But I did. No choice. Wasn't going to pull the dash apart.

After "Restricted Performance" warning and then analysis with the GAP iiD, then ordering (well priced) new parts from LR Direct (UK), I replaced both Mass Air Flow Sensors in the D4 this afternoon. All good.
A wonderful sense of achievement.
I then stood back and admired the absolutely beautiful body design of the D4.
A pleasure and privilege to own one.
Very best,
Jeffoir

Originally Posted by Eric SDV6SE

Ordered new idlers, accessory belt and water pump from AF, I figured after the originals have done 220,000km, it's time to replace as a preventative measure.

Update: ordered last week arrived today. Pretty good considering. Job is booked in weekend after next, got a few other jobs on, 3 kids all with cars leaves little time to tinker on the D4.