Air con (high) pressure switch is called this simply because it is fitted on the high pressure side of the air con system. It will read approx 5bar when compressor switched off and approx 9 bar when compressor is swiched on at full cooling output it is responsible for for feeding information back to ECU on pressures. If pressure gets too high or too low then compressor will be switched off by ECU and fault will be logged in both cases. (There is no other pressure sensor fitted to the system). Not so stupid when you understand how the system actually works. :end_of_discction: