Possible Deviation From Specified Value During The Pressure Test (6 Of 9)

Possible Deviation from Specified Value during the Pressure Test
The specified cooling output is reached, then after a shorter or longer period of time the specified cooling output is no longer reached. The high pressure and the low pressure are normal at first, after some time high pressure increases above the specified value and the low pressure falls to the specified value or lower. The high pressure and the low pressure are normal, then after a period of driving time the low pressure falls to the specified value or lower, the evaporator ices over.
Possible causes for the deviation from specified value and their solutions
Radiator for coolant, condenser is contaminated or the activation of the radiator fan is not OK. -- Check the activation of the radiator fan and if necessary service. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function of the A/C system.-- Check the condenser and radiator for the condenser for contamination and if necessary clean. Refer to Refrigerant Circuit and RADIATOR/RADIATOR FAN . The measured value of the Evaporator Vent Temperature Sensor -G263- is faulty. -- Check the measured value and installation of the Evaporator Vent Temperature Sensor -G263-. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function of the A/C system. Refer to Component Location Overview - A/C System . The activation of the A/C Compressor Regulator Valve -N280- is faulty. -- Check the activation of the A/C Compressor Regulator Valve -N280- and if necessary service. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function of the A/C system. A/C Compressor Regulator Valve -N280- or A/C compressor faulty -- Check the function of the A/C Compressor Regulator Valve -N280- and if necessary remove the A/C Compressor Regulator Valve -N280- and if necessary check for contamination. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function of the A/C system. Refer to COMPONENTS, REPLACING .-- Replace the A/C Compressor Regulator Valve -N280- or the A/C compressor. Refer to COMPONENTS, REPLACING .-- If there is dirt in the refrigerant circuit clean the refrigerant circuit (flush with refrigerant R1234yf) and the expansion valve and desiccant bag/dryer cartridge (or replace the reservoir/receiver/dryer). Refer to REFRIGERANT CIRCUIT, CLEANING , COMPONENTS, REPLACING and Refrigerant Circuit . Moisture in refrigerant circuit -- Extract refrigerant from the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, DISCHARGING .-- Clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .-- Replace the expansion valve and desiccant bag/dryer cartridge (or reservoir/receiver/dryer). Refer to COMPONENTS, REPLACING and 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:

With this malfunction, evaporator may ice up although the quantity of refrigerant in circuit is OK.

A malfunction on the Evaporator Vent Temperature Sensor -G263- can also cause icing-up of refrigerant circuit. For this concern also pay attention to the Evaporator Vent Temperature Sensor -G263- measured value.

If there is moisture in the circuit, discharge the A/C compressor and replace the desiccant bag/dryer cartridge (or receiver/receiver/dryer). After cleaning (flushing with refrigerant R1234yf) fill the refrigerant circuit with the correct quantity of refrigerant oil. Refer to REFRIGERANT CIRCUIT, CLEANING , Technical Data and Refrigerant Circuit .