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Home >> Audi >> 2021 >> A4 Quattro Premium Plus, 2.0L Eng VIN B >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> General Servicing >> Air Conditioning (Refrigerant R1234YF Servicing) (1 Of 2) >> 87 Air Conditioning >> Working With A/C Service Station >> Pressures, Checking >> Electrically-Driven A/C Compressor, Checking Pressure With A/C System Switched On >> Possible Deviation From Specified Value During The Pressure Test (4 Of 12)

Possible Deviation From Specified Value During The Pressure Test (4 Of 12)

Possible Deviation from Specified Value During the Pressure Test
  • High pressure normal
  • Low pressure normal or too low (less than the specified value)
  • The required cooling output is only not attained at the evaporator for cooling the high-voltage components (the cooling output at the front heater and A/C unit evaporator is OK).
Possible causes for the deviation from specified value and their solutions
  • If one of the valves installed in the refrigerant circuit is faulty or does not work correctly. Refer to Refrigerant Circuit .
  • One of the pumps or one of the valves in the high-voltage system coolant circuit is faulty or does not function correctly. Refer to Coolant Circuit .
  • One in or on the removed refrigerant circuit pressure/temperature sensor or temperature sensor sends incorrect values. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding"  function. Refer to Component Location Overview - A/C System .
  • Constriction of blockage in the refrigerant line to or from the expansion valve on the evaporator for cooling the high-voltage components.
-- Check the measured values of the different pressure/temperature sensor and temperature sensor when operating the A/C system, and replace the components with incorrect measured values. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding"  function. Refer to Component Location Overview - A/C System .-- Check the function and activation of the various valves installed in the refrigerant circuit via the pressure distribution in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding"  function. Refer to Refrigerant Circuit .-- Check the function and activation of the components for cooling the high-voltage components. Use Vehicle Diagnostic Tester in the"Guided Fault Finding"  for the air conditioner, the A/C Compressor and the Battery Regulation.-- Depending on the result, service the activation or a faulty component (shut-off valve, expansion valve, coolant pump, coolant shut-off valve). Refer to Refrigerant Circuit and COOLANT CIRCUIT .-- Check the refrigerant circuit lines, if they are kinked or constricted replace the hose or pipe of this component.-- If no malfunction can be determined clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .
NOTE:

Read the supporting information. Refer to Possible Deviation From Specified Value During The Pressure Test (1 Of 12) .