[lowrydr310]

I searched and searched and saw many people commenting with the same problem, but no solutions.

When I first start my car there's warm air blowing out of the vents for several minutes, and then it starts blowing cold. Occasionally while stopped and idling, it's almost as if the AC shuts off and warm air blows again. NOT good when the defroster is on, because as soon as this happens the windshield fogs up with the moist air from the evaporator box.

I used INPA to check the mixer flaps, temperature sensors, temperature settings, and the pressure reading. All work perfectly fine, even the stratification mixer. My radiator fan also works fine; I used INPA to command it to run and it turns on without any issue.

With a cold engine not running, INPA is reporting 5 bar pressure, which is plenty for the compressor to work. After starting it jumps to 5.5 immediately and then while idling or even driving, it slowly starts increasing. I never saw it go over 9 bar, but even then it just briefly spiked there, normally settling around 7 bar.

Sounds like it could be a low refrigerant charge, however I just paid an alleged reputable independent BMW shop to recharge the system. Later when the behavior didn't change, I asked if they did a proper evac and refill based on refrigerant weight and they told me NO they didn't do that, so that's still a possibility.

Could this be a faulty expansion valve? Sticking closed so there isn't enough refrigerant on the low side for the compressor to compress?

I know a bad pressure sensor can cause issues, but I'm getting valid readings that I confirmed with a set of manifold gauges.

Then there's the other option of replacing the compressor itself. I'd hate to waste my time and the cost of refrigerant to replace an expansion valve only to find out I have to replace the compressor and charge the system again. Is there any way to test the expansion valve function and confirm that it's faulty?

[ptpending]

all petrol e9x may have issue with freon pipe on right carrier bar under hood
it is corrode due collecting dust from wheel arch behind heat shield
so the good idea is to replace this whole pipe or weld the new part in it
until this will done all recharges will be temporary
if this issue will not be remediated, the compressor will run on low oil and will die