It could be a lot of things but the first thing that comes to mind is it is overcharged and the hi pressure switches it off when the pressure get to high. This will usually happen after it has been running for a while. If you post in the AC section you will probably get more replies.
The passenger seat is 15 miles an hour faster than the drivers seat.
2017 Giulia Q4
74 GTV restored daily driver
71 Berlina in 2L restored driver
the ones that got away:
1959 750 series Giulietta Spider Veloce
1962 Giulietta Spider normale
1965 Giulia Sprint normale