Error Cooling System pressure to high Airco
If you replaced the expansion valve and has not seen the oil with a grey color it is a good sign that the problem is not with the HVAC compressor.
The high pressure of coolant probably was promoted by you when you overfilled the system. To fill up the system correctly you need a manifold to see the pressure in the low and the hi side at the same time and also, you need that your compressor is engaging.




Not sure how you get the code, as I don't know cooling system has pressure sensor, but if that is so - get new coolant cap


