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A/C refrigerant system (R-134a), components: Notes

HD = High-pressure side 

ND = Low-pressure side 

NOTE:
  • Replacement A/C compressors supplied by Parts Dept. contain the total quantity of refrigerant oil for filling the refrigerant system: 250 cc (8.5 fl oz.)
  • Testing A/C system cooling performance. See A/C REFRIGERANT SYSTEM, TESTING .
  • Do not top-up refrigerant system by adding any refrigerant (drain system, evacuate and re-charge).
  • O-ring diameters and tightening torques stated also apply to the threaded connections of the refrigerant line between individual components. Install only O-rings which are approved for R-134a refrigerant (identified by color coding, at present red or violet).
  • Check pressures in the refrigerant system. See A/C REFRIGERANT SYSTEM (R-134A), CHECKING PRESSURES .
  • Servicing work on A/C system. See A/C SYSTEM REFRIGERANT SYSTEM, SERVICING .
NOTE:
  • For vehicles with Nippondenso compressor, it may be necessary to blow compressed air and nitrogen through the refrigerant circuit between accumulator and compressor in the direction of flow of the refrigerant.
CAUTION:
  • Mark direction of travel for the ribbed belt before removing. Reversing direction could cause the belt to fail.
  • If a new compressor is installed, or if oil has been added, manually rotate the compressor 10 turns before operating the system to prevent compressor damage.
  • Make sure that A/C refrigerant lines are properly insulated from exhaust system heat.
NOTE: The following list refers to items in Fig 1.
  1. Compressor 
    NOTE:
    • Removing and installing ribbed V-belt and checking alignment of belt pulleys

      See RIBBED BELT, REMOVING AND INSTALLING .

    • The piston stroke of compressor is variable and is set as a function of cooling performance required.
  2. A/C compressor speed sensor -G111- 
    • Not applicable for vehicles with Nippondenso compressor
  3. A/C clutch -N25- 
  4. Oil drain plug 
    • 30 Nm (22 ft lb)
    • Installed with sealing ring instead of O-ring
    • Always replace sealing ring
    NOTE: Turn A/C compressor via A/C clutch in order to drain the oil faster.
  5. Pressure relief valve 
    • O-ring: 8.8 * 1.9 mm
    • 10 Nm (7 ft lb)
  6. Connection with valve 
  7. A/C refrigerant high pressure switches -F23- and -F118 
  8. Condenser 
  9. Cap with seal 
    • Always re-install over valve
  10. Service connection 
    • For measuring, draining and re-charging
  11. Threaded connection in refrigerant line 
    • O-ring: 10.8 * 1.8 mm
    • 15 Nm (11 ft lb)
  12. Restrictor 
  13. Evaporator 
    • Removing and installing. See A/C EVAPORATOR, REMOVING AND INSTALLING .
    • O-rings for A/C refrigerant lines:
    • Intake: 10.8 * 1.8 mm
    • Outlet: 17.2 * 1.8 mm

      O-rings (for refrigerant lines on evaporator intermediate piece):

    • Intake and outlet: 13.4 * 2.4 mm

      Tightening torques:

    • Central bolt (refrigerant lines at air conditioner housing): 25 Nm (18 ft lb)
    • Bolts at evaporator: 5 Nm (44 in. lb)
  14. A/C refrigerant low pressure switch -F73- 
    NOTE: To test, bridge electrical connections in harness connector for removed A/C refrigerant low pressure switch -F73-. See A/C REFRIGERANT LOW PRESSURE SWITCH -F73- .
  15. Connection with valve 
    • For A/C refrigerant low pressure switch -F73-
    • For measuring pressures
  16. Accumulator 
  17. Connection with valve 
    • Not applicable for vehicles with Nippondenso compressor
  18. Cap 
    • Not applicable for vehicles with Nippondenso compressor
Fig 1: A/C Refrigerant System Components & Line Diagram
G02729935Courtesy of AUDI OF AMERICA, INC.