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Home >> Audi >> 2017 >> TT Quattro Base, 2D Convertible >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 26 (Air Conditioning (Refrigerant R1234YF Servicing) (2 Of 2) [Coupe]) >> 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 (6 Of 11)

Possible Deviation From Specified Value During The Pressure Test (6 Of 11)

WARNING: This page is about a different variant/trim than selected.
Possible Deviation from Specified Value during the Pressure Test
  • The required cooling output is not attained in the heater and A/C unit evaporator (and in the evaporator for battery cooling).
  • 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
  • The activation of the A/C compressor and if equipped the refrigerant shut-off valve 1 the refrigerant shut-off valve 2 is faulty. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding"  function for the A/C system and the battery regulation.
-- Check the activation and function of the A/C compressor (and if equipped the refrigerant shut-off valve 1 and the refrigerant shut-off valve 2) and if necessary service. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding"  function of the A/C compressor and the battery regulation. If this is OK extract refrigerant from the refrigerant circuit.
  • There is too little refrigerant in the refrigerant circuit.
-- 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)). Refer to Technical Data (vehicle-specific Service Information), and look for leaks and correct. Refer to LEAKS, FINDING .-- If the extracted refrigerant quantity corresponds to the specified capacity or is only slightly smaller (less than 100 g (3.5 oz)). Refer to Technical Data (vehicle-specific Service Information) and Technical Data . Check the refrigerant shut-off valve for function. Refer to the Refrigerant Circuit (vehicle-specific Service Information).
  • The expansion valve for the evaporator in the heater and A/C unit is faulty. Refer to Refrigerant Circuit (vehicle-specific Service Information).
  • A refrigerant shut-off valve is faulty (closed). Use the Vehicle Diagnostic Tester in the"Guided Fault Finding"  function for the A/C system and the battery regulation. Refer to Refrigerant Circuit (vehicle-specific Service Information).
-- If equipped check the function of the installed shut-off valve. Refer to Refrigerant Circuit (vehicle-specific Service Information).-- Replace the expansion valve for the evaporator in the heater and A/C unit. Refer to Refrigerant Circuit (vehicle-specific Service Information).
  • Too much refrigerant oil in the refrigerant circuit
-- Clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .-- Replace the expansion valve for the evaporator in the A/C unit (and for the evaporator for battery cooling) as well as the desiccant bag/dryer cartridge (or receiver/receiver/dryer). Refer to COMPONENTS, REPLACING and Refrigerant Circuit (vehicle-specific Service Information).
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 .