Hello, i recently scanned the car for fault codes and one was for an air con pressure sensor. Could that be the reason why my compressor is always engaged? The engine is a 1.2 htp.

Thanks!

The compressor is a variable displacement type, so always engaged by design. When no cooling is requested it only circulates at approx. 4% duty cycle.

G65 'signal too low' error codes generally indicate that most/all of the refrigerant has leaked out. Does the A/C still do any cooling?

No, it doesn't. 

Thank you for the answer!