My 2015 (3rd gen) car's AC seemed to be working at first on the first warm day a few weeks back but then it stopped after a bit.
I've verified that the clutch spins when it is on
on some drives the AC seems to work perfectly fine. On other drives, it does not seem to activate or if it does it's barely detectable
When it is not working (well), the larger diameter AC pipe under the hood will be cool (not cold) or even a bit warm
There are no major fin integrity issues with the condenser
The AC pipes are intact.

Here are the results of some testing all done with a manifold with the high/low side gauges on the same day:
Observation 1:
Before turning the car on, the low/high side pressure where approximately equal. A short time after turning the car and AC on: the outdoor temperature per the car's thermometer is 97. humidity is 31%. The temperature of air coming from the vents with AC on max is 60f. The car is in the sun. High side reads 225-250psi variable over time. Low side reads 45psi. The recirculate toggle for cabin air is on. Windows open.

Observation 2:
Windows closed: Temperature is set to coldest, fan max. Vents open and vent position set to dashboard level main vents. The temperature coming from the vent is now 57f. Low side pressure 39-42 psi. High side 225-250

Observation 3:
with the fan setting on speed 1, vent temperature is 50.

Observation 4:
so it's now in this setup after having been running for a while
Front windows open
Temperature dial to coolest
Max fan
Dashboard vent position
Recirculate
Vent air is like 74
Low side pressure 12 psi
High side 225
Engine rpm is around 1500-1700

Observation 5:
Passenger vent air temp is 76-80 and driver is 96. Low side is now 0 psi. High 225. Car configuration as before

Observation 6:
After turning off the AC but keeping everything else the same, the low side returned to 28psi

Observation 7:
It immediately went to zero low side psi when I turned it on

Observation 8:
The car has just turned off now and the low side is 10psi and high side 225. When I first started the test, the car had been off for an hour low side was much higher like over 100

Observation 9:
It has been off for 20 minutes or more and the low side is 13 psi and high 190

So what do you think? Expansion valve stuck closed or clogged (intermittently)? That'd be my guess.
Thanks

 

Seems plausible. Replacing the filter/drier media in the condenser end tank is probably wise. If possible, run the system just before servicing it and then get a sample of oil from the compressor. Check the oil and filter for sparkles.

 

Thanks. You mean replacing the desiccant in the condenser because it could be burst from its little bag and/or saturated and not able to absorb any more water?
And the compressor oil sample would be to see if it is starting to shred itself and shed metal into the system or something?
Both of those things could probably clog the expansion valve, eh?

 

I'm thinking the desiccant baggie has some limited mechanical filtering capability. Not so much "remove debris from the refrigerant stream" as "catch some debris so it can be identified".

Correct.
I've been told that Fords had a habit of making a colorful mess in their receiver/drier. I haven't looked into that myself, but it sounded like it must be some refrigerant/oil/desiccant incompatibility that needed fixing after the changeover from R-12 to R-134a. The R-1234yf changeover and PAG to PAO oil (not sure what oil the GK uses) could have similar teething issues. Popping the top on the drier actually seems like a very convenient way get a look inside the system. Aftermarket desiccant + cap kits are around $10.