This bulletin applies to 2011 Volkswagen Routan and other 2000-2011 VW models with A/C and a three-wire G35 pressure sensor.
The A/C pressure sensor G65 is an electronic pressure sensor. It is mounted in the high pressure side of the A/C circuit. The A/C pressure sensor G65 is not a pressure sensing switch like F129, but outputs a digital square wave pulse width modulated signal in proportion to changes in refrigerant high side pressure.
The sensor provides additional information to the control module, sensing the refrigerant pressure throughout the working range. The signal pulse width varies in proportion to system pressure.
At a low pressure of 20.3 psi, the pulse width = 2.6ms or 13% duty cycle. At a high pressure of 536.6 psi, the pulse width = 18ms or 90% duty cycle.