Possible Deviation From Specified Value During The Pressure Test (1 Of 9)

Possible Deviation from Specified Value during the Pressure Test
The requested cooling output is not attained. the high pressure remains constant or increases only slightly (above pressure with engine stopped), The low pressure does not drop or drops only slightly.
Possible causes for the deviation from specified value and their solutions
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 expansion valve and desiccant bag/dryer cartridge (or replace the reservoir/receiver/dryer). Refer to COMPONENTS, REPLACING , Refrigerant Circuit and REFRIGERANT CIRCUIT, CLEANING .
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:

Pay attention that the A/C compressor (the shaft of the A/C compressor) under these concern is actually driven by the belt pulley/the drive unit. Refer to A/C Compressor and Refrigerant Circuit .

In no malfunction is determined for this concern, clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .

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 . Replace the A/C compressor and dryer cartridge (or reservoir/receiver/dryer). Refer to Refrigerant Circuit .

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

If the expansion valve is faulty (constantly closed or does not open far enough), the A/C Compressor Regulator Valve -N280- is actuated to maximum output and the low pressure drops to value in graph or below (the A/C compressor draws off refrigerant from low-pressure side). Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function of the A/C system. As however refrigerant cannot flow via the expansion valve, the cooling output is not attained and high pressure may also not increase or only increase slightly due to the absence of energy conversion.