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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 >> Mechanically Driven A/C Compressor, Checking Pressure With A/C System Switched On >> Possible Deviation From Specified Value During The Pressure Test (2 Of 9)

Possible Deviation From Specified Value During The Pressure Test (2 Of 9)

Possible Deviation from Specified Value During the Pressure Test
  • The requested cooling output is not attained.
  • The high pressure pipe corresponds to the specified value
  • The low pressure corresponds to the specified value or is too low
Possible causes for the deviation from specified value and their solutions
  • There is too little refrigerant in the refrigerant circuit.
  • The expansion valve is faulty.
-- Extract refrigerant from the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, DISCHARGING .-- If the extracted refrigerant quantity is significantly less than the specified capacity (more that 100 g (3.5 oz) less). Refer to Technical Data , and look for leaks and correct. Refer to LEAKS, FINDING .-- The extracted refrigerant quantity corresponds approximately to the specified capacity, replace expansion valve for the evaporator in the heater and A/C unit. Refer to Refrigerant Circuit .
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to MECHANICALLY DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .
NOTE:

Check the measured values of the Evaporator Vent Temperature Sensor -G263- and the activation of the A/C Compressor Regulator Valve -N280-. If the measured value of the Evaporator Vent Temperature Sensor -G263- malfunctions the evaporator can ice over or the cooling output is not reached. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding"  function of the A/C system.

If the A/C system function is not OK after repeating the test, for example after replacing expansion valve, clean the refrigerant circuit by flushing using the refrigerant R1234yf. Refer to REFRIGERANT CIRCUIT, CLEANING . Then replace the A/C compressor and reservoir/receiver/dryer (or dryer cartridge). Refer to Refrigerant Circuit .