Odd AC issue
 

Hey folks,

Just got a new to me 2003 X5 3.0 with the calsonic compressor. AC didn't work, but NBD I'm pretty handy and figured I could sort it out. However after giving it a look over this AM I'm a bit stymied.

TL;DR everything I can think of seems to check out pretty well, but AC doesn't work even though clutch spins.

First thing I did was put gauges on it to see whether it was hopefully just a little low on R134a.

Low and high side were both around 90psi with AC off. Which seems reasonable, and no leaks.

INPA scan shows ambient and interior temp sensors reading correctly.

AC pressure sensor @ 1.2-1.3V depending upon gauge reading.

Turning on AC / Max AC activates clutch which begins spinning; RPM rises; INPA shows Compressor Input and Output as ON.

Local BMW dealership replaced AC clutch sometime in the last year (November 2018 IIRC).

My understanding is that this is a "variable displacement" compressor which means there is some internal control over compressor load and the clutch isn't a binary on/off switch with the traditional loud "click" and jolt when activated and is controlled to some degree by PWM?

At any rate, I'm not really sure how to proceed from here or what my findings signify? Clutch issue with the newly replaced part? Compressor? Something else? Are there any other models which use a similar setup which might provide diagnostic pointers as I haven't turned up much in my X5 specific searches (AC clutch turning, but not compressing).

Thanks for any help!

Fan has checked out (unplugged pressure sensor and went into fast spin).

Going to disconnect compressor clutch power line and see what voltage it puts out. I assume that is the line that receives the PWM / variable voltage signal?

EDIT: got 3-5V initially, but ramped up to ~12.8V or so. As I mentioned clutch was replaced by dealer within the last 6 months or so, so I'm going to tentatively call it the compressor and see if I can score a used one to slap in.

The solenoid valve for the variable compressor probably needs to be replaced, but you never posted what the low and high side readings were with the clutch engaged.
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Sorry, I thought I mentioned but didn't, the clutch engagement has no effect on pressures (other than climbing a bit eventually due to heat soak from the engine)

i.e. the clutch engages, but the compressor doesn't seem to.

Just to provide closure, I tracked down a used compressor, installed and charged, and everything works great now. Not sure what specifically it was (above mentioned solenoid valve) but it was something with the compressor and is now fixed.