Quick-Release Coupling Connections On Refrigerant Circuit: Notes

Service connections with Schrader valve (needle valve or Push Pin)

• Only valves and connections that are designed for primarily high pressures and are resistant to refrigerant R744 and the associated refrigerant oil may be used.

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

• The service connections -C- (high-pressure side) and -F- (low-pressure side) on a R744 refrigerant circuit are designed so that the service couplings designed for the service connections on a R1234yf or R134a refrigerant circuit cannot be connected.
• There are different connections (outer diameter) for the high-pressure and low-pressure side -C and F-.
• Discharge the refrigerant circuit before removing the valve inserts -B and E-.
• Always install the caps -A and D-.
• To protect the seals in the service couplings, check the service connections -C and F- for dirt and clean them if necessary before installing the service couplings on the service connections.
• Due to the high pressures in the refrigerant circuit, the service couplings for the refrigerant have a protection function. Depending on the version, they cannot be removed as long as there is pressure in the space between the valve inserts -B and E- and the service coupling, or the pressure in this space (dead air space) is released via a bypass opening when removing the hand wheel.
• After removing the service couplings, check the valve inserts in the service connections for leaks (there are no seals installed in the caps -A and D-).
• The caps for the service connections -A and D- do not have a seal because of the high refrigerant circuit pressure. If the valve insert seal is no longer tight (the maximum amount allowed to leak via a valve insert is less than 2 g (0.1 oz) per year) due to an old valve insert -B and E- or dirt particles, refrigerant will continue to leak out over time.
• The caps -A and D- do not have a seal; they only protect the service connection from dirt.
• The caps -A and D- must not be equipped with a seal because of the high pressures in the refrigerant circuit (if a valve is leaking, too great of a pressure may build under the cap and it could fly off).
• The valve inserts -B and E- are currently identical in construction.
• Allocation in the vehicle. Refer to Refrigerant Circuit (vehicle-specific Service Information).
• After connecting, carefully install the service coupling hand wheel just far enough into the quick-release coupling adapter until the valve is securely opened inside the service connection (pay attention to the pressure gauge, do not put too much pressure on the valve).
• Tighten the valve insert very carefully because the tightening specification is very small.