Airconditioning does not work

[JoeCool88]

When switching on the AC on my 2018 94Ah i3 (with heat pump), to cool down the cabin @ +30C OAT, nothing happened. The malfunction storage says "error 801131: low level AC-Circuit" (among other errors). I checked the LP and HP in the system, with approx. 55 PSI both (static!) this seems to be okay. When the pressure is okay, hence there is enough r1234yF in the circuit, the LP sensor p/n 64539306476 which detects low level could have a malfunction. This sensor has 4 pins and is described as a combined pressure and temperature sensor. Between the pins I get readings between 2,7 and 14,6 kOhms, but without a data sheet of the sensor, or a wiring diagram of the airconditioning system, I could not see whether this is correct or not. Could anybody help me out with a data sheet of this sensor and/or a ac wiring diagram, or tell me where I could find such stuff in the web?
Many thanks!

 

[JoeCool88]

After clearing the malfunction storage and another test drive error code 801131, underfilling AC-circuit, appeared. I measured the static pressure in the AC system which is 55 psi @ 79°F OAT. As the compressor is not running LP = HP, both 55 psi. The only thing I could find in the web was a general R1234yF pressure-temperature chart, which says that at 79°F the pressure should be 87 psi. Has anybody out there values for the (static) low pressure in the i3 AC circuit, related to a given ambient air temperature?