Refrigerant Circuit, Servicing

HD = High-pressure end 

ND = Low-pressure end 

1. A/C Compressor Regulator Valve -N280-
   • Do not remove.
   • Check activation and function, refer to A/C COMPRESSOR REGULATOR VALVE, CHECKING SWITCH-ON SIGNAL .
     NOTE:

     The A/C compressor regulator valve is controlled by the Climatronic Control Module -J255- / A/C Control Module -J301-.These control modules control the pressure on the low pressure side of the refrigerant circuit.

2. A/C Compressor
   • A/C compressor, removing from bracket and reinstalling, refer to COMPRESSOR, REMOVING FROM BRACKET .
   • A/C compressor refrigerant line, disconnecting and reconnecting, refer to REFRIGERANT LINES, DISCONNECTING FROM A/C COMPRESSOR .
   • To protect the A/C compressor, the engine should only be started with the refrigerant circuit completely assembled.
   • Remove ribbed belt, refer to RIBBED BELT .
   • A/C compressor, removing and installing, refer to A/C COMPRESSOR .
   • Depending on time period of production and on engine, compressor construction type may vary.
   • At the beginning of production, A/C compressor was manufactured by Denso (type 7 SEU 16 or 7 SEU 17) were installed; from MY 2004 A/C compressors by other manufacturers (Delphi, Sanden or Zexel) may also be installed. Refer to Removal and Installation .
     NOTE:

     Beginning the production year 2006, the name of the Zexel A/C compressor was changed from Zexel to Valeo.

   • These A/C compressors are available as replacement parts with different oil fill capacities, therefore note capacity on A/C compressor REFRIGERANT R134A CAPACITIES .
   • Depending on A/C compressor type, different refrigerant oil fill capacities are designated for the refrigerant circuit. The reason for the different oil capacities in the A/C compressor for an otherwise identical refrigerant circuit lies in the design of the A/C compressor itself, note these oil capacities. Too much oil in the circuit leads to higher pressures and reduces cooling performance of the system. Too little oil may lead to lubrication problems in the compressor.
   • If a new compressor has been installed or new refrigerant oil has been put into the A/C compressor (e.g. after blowing through the A/C system), the A/C compressor must be turned by hand approximately 10 revolutions. This ensures that the compressor is not damaged when activated.
3. Belt Pulley
   • Replacing, refer to A/C COMPRESSOR AND PULLEY .
   • Ribbed belt, removing and installing, refer to RIBBED BELT .
   • The Delphi A/C compressor belt pulley cannot be removed separately.
   NOTE:

   • There is an overload protection installed between the belt pulley and the A/C compressor input shaft to protect the belt should the A/C compressor get blocked or be difficult to move.
   • If the A/C compressor is runs with resistance, the overload safeguard interrupts the supply of power to it.
   • Rubber elements are installed between belt pulley and A/C compressor driveshaft, vibrations which may occur during A/ C compressor operation may be dissipated via these rubber elements (damper function at torque fluctuations).
   • Different versions of the pulley are installed depending on the type of A/C compressor and engine, refer to A/C COMPRESSOR AND PULLEY 
4. Oil Drain Plug
   • Denso and Delphi A/C compressors have a sealing ring installed, replace.
   • Sanden A/C compressors have an O-ring (8.8 mm x 1.5 mm) installed, always replace.
   • Zexel/Valeo A/C compressors have an O-ring (7.6 mm x 1.9 mm) installed, always replace.
     NOTE:

     Beginning the production year 2006, the name of the Zexel A/C compressor was changed from Zexel to Valeo.

   • Tightening specifications: Denso A/C compressor 30 Nm, Sanden- A/C compressor and Zexel- A/C compressor 10 Nm.
   • Tightening specifications: Delphi A/C compressor 15 Nm.
   • Should only be unscrewed to drain refrigerant oil and with the A/C compressor removed. Turn the A/C compressor via belt pulley, to speed up refrigerant oil drainage. Refer to Removal and Installation .
5. Pressure Relief Valve
   • Do not remove
   • Tightening specification: Sanden A/C compressor 14.5 Nm, Denso A/C compressor and Zexel / Valeo A/C compressors 10 Nm
   • with O-ring Denso A/C compressor, Sanden A/C compressor and Zexel / Valeo A/C compressor: 8.5 mm x 1.75 mm
   • Delphi A/C compressor with sealing ring, tightening specification: 15 Nm.
6. Connection With Valve
   • Different component locations depending on engine, item 6a shows component location in vehicles with 2.0 L Diesel engine.
   • For removing and installing the valve set when the refrigerant circuit is evacuated, for example, use an adapter from the Socket For A/C Valves T10364.
7. High Pressure Sensor -G65-
   • Removing and installing, refer to HIGH PRESSURE SENSOR .
   • Checking signal, refer to HIGH PRESSURE SENSOR, CHECKING PRESSURE SIGNAL .
   • Different component locations depending on engine, item 7a shows component location in vehicles with 2.0 L Diesel engine.
8. Condenser
   • Refrigerant lines, disconnecting and reconnecting, refer to REFRIGERANT LINES, DISCONNECTING FROM CONDENSER .
   • Condenser, removing and installing, refer to CONDENSER .
9. Fluid Reservoir
   • Coat O-ring seals lightly with refrigerant oil before installing, refer to REFRIGERANT CIRCUIT O-RINGS .
   • Replace the O-ring seals.
   • Removing and installing, refer to FLUID RESERVOIR .
   • Different versions (secured by one or two bolts, with or without seals against moisture in connection area).
     NOTE:

     The reservoir may be attached to or integrated in the condenser, depending on the version of the condenser. Refer to FLUID RESERVOIR  and DRYER CARTRIDGE .

   • Dryer cartridge (on a condenser with an integrated fluid reservoir), removing and installing, refer to DRYER CARTRIDGE .
10. Service Connection
    • High pressure side.
    • Different versions (with primary sealing valve or with Schrader valve) depending on refrigerant line, distinguishing characteristics, refer to CONNECTIONS FOR QUICK-RELEASE COUPLING ON REFRIGERANT CIRCUIT .
    • For the A/C Service Station for measuring, discharging and recharging using service station, refer to A/C SERVICE STATION .
    • Depending on engine version, it may be necessary to remove some components (e.g. EVAP canister) in order to be able to connect to service coupling.
    • For removing and installing the service connection or the valve set when the refrigerant circuit is evacuated, for example, use an adapter from the Socket For A/C Valves T10364.
      WARNING:

      Only remove service connections when the refrigerant circuit is empty. The connection does not have a valve.

11. Sealing Cap
    • With a seal.
    • Always screw on.
12. Expansion Valve
    • Refrigerant lines, disconnecting and reconnecting, refer to REFRIGERANT LINES, DISCONNECTING FROM EXPANSION VALVE .
    • Removing and installing, refer to EXPANSION VALVE .
      NOTE:

      After switching off the A/C compressor on this vehicle, it may take a long time until the pressure on the high pressure side (the expansion valve is cold and the pressure on the low pressure side increases quickly after switching off, the expansion valve closes and the refrigerant can flow slowly on the low pressure side.

13. Evaporator
    • A/C unit with evaporator, removing and installing, refer to HEATING AND A/C UNIT .
    • Removing and installing evaporator from heating A/C unit, refer to EVAPORATOR .
14. Service Connection
    • Low pressure side.
    • Different versions (with primary sealing valve or with Schrader valve) depending on refrigerant line, distinguishing characteristics, refer to CONNECTIONS FOR QUICK-RELEASE COUPLING ON REFRIGERANT CIRCUIT .
    • For the A/C Service Station for measuring and discharging using service station, refer to A/C SERVICE STATION .
    • Depending on engine version, it may be necessary to remove some components (e.g. EVAP canister) in order to be able to connect to service coupling.
    • For removing and installing the service connection or the valve set when the refrigerant circuit is evacuated, for example, use an adapter from the Socket For A/C Valves T10364.
      WARNING:

      Only remove service connections when the refrigerant circuit is empty. The connection does not have a valve.

15. Sealing Cap
    • With a seal.
    • Always screw on.
16. Pre-Volume
    • Is a component of refrigerant line from expansion valve to A/C compressor.
    • Pressure fluctuations are damped in the pre-volume.
    • Not installed in all vehicles (currently only on 2.0L diesel engines).
17. Connection in Refrigerant Line
    • Replace the O-ring seal.
    • Not installed in all vehicles (for example, installed in 6-cylinder vehicles).
    • Disconnecting and connecting connection, refer to CONNECTING POINTS IN REFRIGERANT LINE, DISCONNECTING AND CONNECTING .