Hello,

I have a 2006 L322 4.4L Jag engine.

Recently it started to provide less cool air through the AC system. Numbers were: about 20 degrees C from air vent, 60 psi suction side refrigerant, 150 psi discharge side refrigerant. I mis-diagnosed the problem as a faulty thermostatic expansion valve and went to the trouble of replacing the valve. It does give slightly better cooling at the air vents of about 18 degrees C but the pressures did not change. There was no debris or signs of compressor damage at the valve, which was perfectly clean at the orifices.

I think it is a compressor failure. I am now wondering what compressor to install. My Rave service procedures manual dates back to 2002 and it makes reference to a the compressor being a fixed displacement compressor. However, the 2006 had some significant updates with the Jag engine and I do not know if the more modern variable displacement compressor was originally installed.

The currently installed compressor is a Sanden PXV16 with an LR Part No. JPB500210. I am not sure if this is a fixed displacement or variable displacement compressor. Also, I am not sure if this was the originally installed compressor when the car was factory new. Sanden does make a variable displacement version of the PXV16. In any case, I am wondering if there might be a fuel efficiency or other operational benefit to installing a variable displacement compressor.

I would appreciate any opinions for and against.

Cheers,

No idea what year they were changed from, but If you can see it, you can determine if it is fixed displacement or not.
Unfortunately the PXV16 reference doesn't give the answer.

Does the pulley have an electronic clutch ?
If it does, it is fixed displacement.

If it doesn't and the wiring goes to a round PCV (Pressure Control Valve) on the back of the compressor, then it is variable displacement.

There are some pictures of my compressor from my 2010 4.4tdv8, which might help to give you a clue what and where the PCV is. Too many toys, not enough time

2011 4.4 TDV8 AB Black

Thanks John.

You are correct that the PXV16 nomenclature does not define the compressor. To complicate things further, variable displacement compressors come in 2 forms:
- an externally controlled form with a solenoid valve commanded by the car's computer to adjust the swash plate
- an internally controlled form with a pressure valve responding to suction pressure to adjust the swash plate.

For sure I do not have the externally controlled form so that narrows my search somewhat. Only question remaining is should I pursue the internally controlled form?

The lazy solution is to just replace the one that is currently installed and I might just do that. But this is an opportunity to perhaps install a better solution.

Attached is pic of nameplate on existing installed compressor.

Cheers,

Oops, here is pic.

This one?

Click image to enlarge

Yes, that is the one currently installed. Not sure why the picture is not showing up in the thread.

Any comments on fixed vs variable displacement?

No idea sorry. I was just fixing the picture for you  2016 Skoda Octavia VRS Estate
<gone>2009 FF Vogue TDV8 Buckingham Blue</gone>
<gone>2015 BMW 520D SE (not my favourite car)</gone>
<gone>2009 D3 HSE Galway Green</gone>

Ok. Thanks.

The compressor installation is now done. Installation is successful and I have nice cold air coming out at 6 degrees C.

Overall, I am satisfied with the initial performance of the new compressor over the first 3 days of operation. The new compressor seems to be well constructed. There were 2 concerns:

One related to a lack of documentation with the unit purchased through Amazon from BuyAutoParts. There was no nameplate, no indication of whether it was shipped with oil, etc. Before ordering I had an initial question that the sales people at the BuyAutoParts were unable to answer namely; is this a fixed displacement or variable displacement compressor. I took a chance in ordering it based on Amazon’s customer satisfaction guarantee that it was the correct fit for my vehicle (2006 Range Rover HSE). Upon delivery, I was able to confirm that it seems to have the valve for internal control of a variable displacement compressor and that it was therefore the correct type.

Click image to enlarge

Here is a close-up of the metal plate for the electrical connection on the old compressor. Picture rotated.

Well here is an update six years later. The compressor failed after 6 years of service. I put the pressure gauges on it and it shows very little little pressure differential across the compressor. But the system is full of refrigerant and there has been no loss since installation.

My first test was done on warm 20 C (about 70 F) day using only a suction side pressure gauge. SVP for that day was about 100 psi and that showed on the suction of the compressor. I turned on the engine and the turned on the air conditioning system. The clutch kicked in and I confirmed that the compressor was running. There was a momentary flicker on the pressure gauge but it remained at about 100 psi.

My second test was done a few days later with a complete gauge set on a much cooler day (Florida drastic drop in temperature in January 2025). Temp was 7 C (about 46 F). SVP for this day was about 40 psi and that showed on the 2 gauges - low and high pressure sides before I started the engine. I turned on the engine and turned on the air conditioning system. The clutch kicked in and I confirmed that the compressor was running. There was an small drawdown of pressure on the low side to 35 psi and a small increase in pressure on the high side to 52 psi. I repeated this test and the numbers remained the same.

I think I will try this again on a warm day with the complete gauge set just to ensure that the compressor has indeed failed due to some mechanical fault

My preliminary conclusion is that the mechanical variable displacement system has failed or that the reed valves have failed resulting in no-flow of refrigerant.

I am wondering if either of those failures might have resulted in debris being introduced into the system and if I will need to flush and/or replace the drier and/or condenser. I am also wondering if I should disconnect the compressor clutch for now as I want to drive on a long road trip soon and will not need a/c.