Manual:AUDI A3 Premium, 4D Sedan 2015Page:50029 / 92758



Specified Values For The Refrigerant Circuit Pressures — 2015 Audi A3 Premium, 4D Sedan Service Manual

Specified Values For The Refrigerant Circuit Pressures

  • Pay attention to the test requirements and check the pressure. Refer to PRESSURES, CHECKING .

CHECKING: 

-- Bring the engine speed up to 2000 RPM.

-- Pay attention to the pressure indicator (for example the pressure gauge) of the A/C service station. Refer to the A/C service station Owner's Manual.

NOTE:

The switching pressures for the activation of the A/C Compressor Regulator Valve -N280- and the radiator fan are vehicle-specific. use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function for the A/C system.

Pressures must be measured at the service connections; the component location for these connections are vehicle-specific. Refer to PRESSURES, CHECKING / REFRIGERANT CIRCUIT / REFRIGERANT CIRCUIT (R1234yf) (vehicle-specific repair information).

High-Pressure Side: 

Increasing from initial pressure (when connecting the pressure gauges) to a maximum of 20 bar (290 psi).

Low-Pressure Side: 

Decreasing from initial pressure (when connecting the pressure gauges) to a value between 1.5 and 2.3 bar (21.76 to 33.36 psi) absolute pressure (depending on the required cooling output).

NOTE:

If high cooling output is needed (for example, the outside temperature is very high, the blower speed it set on high but the engine speeds are low), then the A/C compressor will not bring the pressure on the low pressure side to the specified value (for example, for a certain time after turning on the A/C). The A/C compressor is actuated with maximum specified control current, however delivery volume is no longer sufficient at this engine speed to reduce pressure on low-pressure side to the specified value. To check the A/C compressor control under these conditions, for example, the fresh air blower is activated only with approximately 40% of the maximum output (voltage), check the pressures at a lower fresh air blower speed. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function for A/C system. Refer to COOLING OUTPUT, CHECKING, VEHICLES WITH AUTOMATIC CLIMATE CONTROL SYSTEM (WITH HIGH VOLTAGE SYSTEM) / COOLING OUTPUT, CHECKING / COOLING OUTPUT, CHECKING (vehicle-specific repair information).

If there is a low cooling output (for example an exterior temperature of 20 °C (68 °F) and a low fresh air blower speed) the pressure on the high pressure side increases only to a value of 6 to 7 bar (87 to 101.5 psi) (the absence of energy is low, the refrigerant is quickly cooled in the condenser). To check the A/C compressor control and the pressure in the refrigerant circuit under these conditions for example the activating the fresh air blower with maximum voltage, adjusting the A/C system to maximum heat output and recirculating air mode. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function of the A/C system. Refer to COOLING OUTPUT, CHECKING, VEHICLES WITH AUTOMATIC CLIMATE CONTROL SYSTEM (WITH HIGH VOLTAGE SYSTEM) / COOLING OUTPUT, CHECKING / COOLING OUTPUT, CHECKING (vehicle-specific repair information).

Under unfavorable conditions (very high ambient temperatures, high humidity), pressure on high-pressure side may increase to max. 29 bar (421 psi).

The specified operating current for the A/C Compressor Regulator Valve -N280- is displayed as the measured value of the Front A/C Display Control Head -E87-, the A/C Control Module -J301- of the Climatronic Control Module -J255-. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function of the A/C system.

The measured high pressure from the High Pressure Sensor -G65-, from the Refrigerant Circuit Pressure Sensor -G805- or the A/C Pressure/Temperature Sensor -G395- is displayed as the measured value of the Front A/C Display Control Head -E87-, the A/C Control Module -J301- or the Climatronic Control Module -J255-. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function of the A/C system.

Low pressure settles depending on control current for A/C Compressor Regulator Valve -N280- and control characteristic of expansion valve within compressor output range in tolerance range. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function of the A/C system.

Under unfavorable conditions (very high ambient temperatures, or high humidity) the output of the A/C compressor may not always be sufficient to attain the specified pressure values within the specified time (depending on the engine speed it can take longer until the specified low pressure can be reached).

If the A/C compressor load is greater than 90%, the pressure on the low pressure side can be greater than the specified tolerance range. The A/C compressor load is no longer sufficient to reduce the pressure on the low pressure side to the value of approximately 2 bar (29 psi) under predominant ambient conditions (ambient temperature, humidity, A/C compressor settings, engine speed etc.).

The specified operating current for the A/C Compressor Regulator Valve -N280- must be greater than 0.3 A in order to ensure reliable A/C Compressor Regulator Valve -N280- actuation. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function of the A/C system.

In "maximum cooling output" setting, control current for A/C Compressor Regulator Valve -N280- is regulated to approximately 0.65 A (up to 0.85 A). The measured value is vehicle-specific and is displayed in the Vehicle Diagnostic Tester in the "Guided Fault Finding" function of the A/C system.

At absolute pressure, 0 bar (0 psi) corresponds to absolute vacuum. Normal ambient pressure corresponds to 1 bar (14.5 psi) absolute pressure. 0 bar (0 psi) pressure corresponds to an absolute pressure of 1 bar (14.5 psi) on most pressure gauges (indicated for example by -1 bar (-14.5 psi) below 0). Depending on the version of the corresponding control module the pressure is displayed as a measured value on the basis of the absolute pressure and relative pressure (difference between the display 1 bar (14.5 psi)). Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function of the A/C system. Refer to COOLING OUTPUT, CHECKING, VEHICLES WITH AUTOMATIC CLIMATE CONTROL SYSTEM (WITH HIGH VOLTAGE SYSTEM) / COOLING OUTPUT, CHECKING / COOLING OUTPUT, CHECKING (vehicle-specific repair information).

The temperature of the air downstream from evaporator, the current A/C compressor speed and the pressure of the refrigerant on the high pressure side as well as the specified operating current for the A/C Compressor Regulator Valve -N280- is displayed for example as the measured value of the display control head of the Climatronic Control Module -J255-. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function of the A/C system.

Possible Deviation From Specified Value, The Cause And Its Elimination  
  • The requested cooling output is not attained.
  • the high pressure remains constant or increases only slightly (above pressure with engine stopped),
  • The low pressure quickly drops to target value or lower.
 Refer to MECHANICALLY DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON 
  • 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
 Refer to MECHANICALLY DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON 
  • Required cooling output is not attained
  • The high pressure does not increase or only increases slightly above pressure with engine stopped
  • The low pressure does not drop or drops only slightly
 Refer to MECHANICALLY DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON 
  • Required cooling output is not attained
  • The high pressure increases above specification
  • The low pressure quickly drops to target value or lower
 Refer to MECHANICALLY DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON 
  • The required cooling is reached next after some or a long running time the cooling output is no longer sufficient.
  • The high pressure and low pressure are normal.
  • After some time the high pressure raises above the specified value, the low pressure corresponds to the specified value or it falls under the specified value.
 Refer to MECHANICALLY DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON 
  • 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.
 Refer to MECHANICALLY DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON 
  • The required cooling performance is obtained.
  • The high pressure pipe corresponds to the specified value
  • The low pressure is too low (lower than the target value)
 Refer to MECHANICALLY DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON 
  • The A/C compressor noise (particularly after switch-on)
  • The required cooling performance is obtained.
  • High pressure normal or too high
  • The low pressure is normal or too high (the specified value is not always reached,
 Refer to MECHANICALLY DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON 
  • The requested cooling output is not attained.
  • The high pressure and the low pressure corresponds to the specified value
 Refer to MECHANICALLY DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON 
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 , OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING (vehicle-specific repair information) 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 / A/C COMPRESSOR, REMOVING AND INSTALLING ON BRACKET / A/C COMPRESSOR, REMOVING AND INSTALLING (vehicle-specific repair information) and REFRIGERANT CIRCUIT / REFRIGERANT CIRCUIT (R1234yf) (vehicle-specific repair information).

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 A/C COMPRESSOR, REMOVING AND INSTALLING ON BRACKET / A/C COMPRESSOR, REMOVING AND INSTALLING / A/C COMPRESSOR / OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING (vehicle-specific repair information).

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.

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 100g (3.5 oz) less). Refer to TECHNICAL DATA (R1234yf SERVICING) (vehicle-specific repair information), 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 / REFRIGERANT CIRCUIT (R1234yf) (vehicle-specific repair information).
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 A/C COMPRESSOR, REMOVING AND INSTALLING ON BRACKET / A/C COMPRESSOR, REMOVING AND INSTALLING / A/C COMPRESSOR / OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING (vehicle-specific repair information).

Possible Deviation from Specified Value during the Pressure Test
  • Required cooling output is not attained
  • The high pressure does not increase or only increases 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 A/C compressor is not driver or not driven with the specified speed.
-- Check the A/C compressor drive (via the belt or drive unit). Refer to A/C COMPRESSOR (vehicle-specific repair information).
  • The activation of the A/C Compressor Regulator Valve -N280- (the A/C Clutch -N25-) is faulty.
-- Check the activation of the A/C Compressor Regulator Valve -N280- (and the A/C Clutch -N25-) and if necessary service. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function of the A/C compressor.
  • 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), expansion valve and desiccant bag/dryer cartridge (or replace the reservoir/receiver/dryer). Refer to COMPONENTS, REPLACING , REFRIGERANT CIRCUIT, CLEANING PROCESS (R1234yf) / REFRIGERANT CIRCUIT, CLEANING (R1234yf) - FLUSHING (vehicle-specific repair information) and REFRIGERANT CIRCUIT, CLEANING .
  • Constriction or obstruction in refrigerant circuit (for example, inside the refrigerant line between the service connection "low pressure side" and the A/C compressor).
-- Run hand over refrigerant circuit to check for differences in temperature. Refer to COOLING OUTPUT, CHECKING, VEHICLES WITH AUTOMATIC CLIMATE CONTROL SYSTEM (WITH HIGH VOLTAGE SYSTEM) / COOLING OUTPUT, CHECKING / COOLING OUTPUT, CHECKING (vehicle-specific repair information). If on a component differences in temperature is determined, because the hose or pipe are kinked or constricted, replace this component. If there is a blockage or no malfunction can be determined, 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 OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING (vehicle-specific repair information).
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:

Make sure that the A/C compressor (the A/C compressor shaft) is actually being driven by the belt pulley/drive unit for this complaint (pay attention to the overload protection). Refer to A/C COMPRESSOR (vehicle-specific repair information).

For some engines, A/C compressor are being introduced that, in addition to the A/C Compressor Regulator Valve -N280-, an A/C Clutch -N25- is being attached to the belt pulley. Make sure that the A/C Clutch -N25- is actually being actuated and the A/C compressor (A/C compressor shaft) is being driven by the belt pulley. Refer to (vehicle-specific repair information) and to the Parts Information.

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 . Then replace the A/C compressor and reservoir/receiver/dryer (or dryer cartridge). Refer to OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING / A/C COMPRESSOR, REMOVING AND INSTALLING ON BRACKET / A/C COMPRESSOR, REMOVING AND INSTALLING / A/C COMPRESSOR (vehicle-specific repair information).

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.

Possible Deviation From Specified Value During The Pressure Test
  • Required cooling output is not attained
  • The high pressure increases above specification
  • The low pressure quickly drops to target value or lower
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. -- If equipped check the function of the installed shut-off valve. Refer to REFRIGERANT CIRCUIT / REFRIGERANT CIRCUIT (R1234yf) / / REFRIGERANT SHUT-OFF VALVES (R1234yf) (vehicle-specific repair information).-- Run hand over refrigerant circuit to check for differences in temperature. Refer to COOLING OUTPUT, CHECKING, VEHICLES WITH AUTOMATIC CLIMATE CONTROL SYSTEM (WITH HIGH VOLTAGE SYSTEM) / COOLING OUTPUT, CHECKING / COOLING OUTPUT, CHECKING (vehicle-specific repair information). If on a component differences in temperature is determined, because the hose or pipe are kinked or constricted, replace this component. If there is a blockage or no malfunction can be determined, 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 OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING (vehicle-specific repair information).
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.

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 low pressure drops to value in graph or below (the A/C compressor draws off refrigerant from low-pressure side). As the refrigerant cannot flow via the expansion valve, if the cooling output is not attained, high pressure may also not increase or only increase slightly due to the absence of energy. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for the A/C system. Refer to REFRIGERANT CIRCUIT / REFRIGERANT CIRCUIT (R1234yf) (vehicle-specific repair information).

If there is too much refrigerant oil in the circuit, the A/C compressor must be emptied and the desiccant bag (the dryer cartridge) or the receiver/receiver/dryer must be replaced. After cleaning (flushing with refrigerant R1234yf) fill the refrigerant circuit with the correct quantity of refrigerant oil. Refer to TECHNICAL DATA (R1234yf SERVICING)REFRIGERANT CIRCUIT, CLEANING , (vehicle-specific repair information) and REFRIGERANT CIRCUIT / REFRIGERANT CIRCUIT (R1234yf) (vehicle-specific repair information).

If the specified value when repeating the check is still not reached and on the refrigerant circuit no malfunction can be determined, clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .

Possible Deviation From Specified Value During The Pressure Test
  • The required cooling is reached next after some or a long running time the cooling output is no longer sufficient.
  • The high pressure and low pressure are normal.
  • After some time the high pressure raises above the specified value, the low pressure corresponds to the specified value or it falls under the specified value.
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 / REFRIGERANT CIRCUIT (R1234yf) / OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE (vehicle-specific repair information) and RADIATOR FAN -V7-, REMOVING AND INSTALLING [CNSB, CNTC] / RADIATOR FAN -V7- AND RADIATOR FAN 2 -V177-, REMOVING AND INSTALLING [CRUA, DEJA] / AUXILIARY RADIATOR, REMOVING AND INSTALLING [CNSB, CNTC, CYFB] .
  • The activation of the A/C Compressor Regulator Valve -N280- is faulty.
-- Check the activation of the A/C Compressor Regulator Valve -N280- and the measured value of the Evaporator Vent Temperature Sensor -G263- and if necessary service. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function of the A/C system.
  • Too much refrigerant in the refrigerant circuit
-- Extract refrigerant from the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, DISCHARGING .-- If the extracted refrigerant quantity is substantially greater (more than 100g (3.5 oz)) than the specified capacity. There is too much refrigerant in the refrigerant circuit. Refill the refrigerant circuit with the correct quantity of R1234yf and repeat the test. Refer to TECHNICAL DATA (R1234yf SERVICING) (vehicle-specific repair information).
  • 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 / A/C COMPRESSOR REGULATOR VALVE -N280-, REMOVING AND INSTALLING .-- If there is dirt in the refrigerant circuit clean the refrigerant circuit (flush with refrigerant R1234yf), expansion valve and desiccant bag/dryer cartridge (or replace the reservoir/receiver/dryer). Refer to COMPONENTS, REPLACING , OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING , REFRIGERANT CIRCUIT, CLEANING PROCESS (R1234yf) / REFRIGERANT CIRCUIT, CLEANING (R1234yf) - FLUSHING (vehicle-specific repair information) and REFRIGERANT CIRCUIT, CLEANING .
  • Too much refrigerant oil in the refrigerant circuit
  • Moisture in refrigerant circuit
-- Extract refrigerant from the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, DISCHARGING .-- If the extracted refrigerant quantity meets the specified capacity is only slightly smaller (maximum 100g (3.5 oz)). Refer to TECHNICAL DATA (R1234yf SERVICING) (vehicle-specific repair information) too much refrigerant oil is in the refrigerant circuit.-- 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 DRYER CARTRIDGE, REMOVING AND INSTALLING (vehicle-specific repair information).
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:

If there is too much refrigerant oil in the circuit, the A/C compressor must be emptied and the desiccant bag (the dryer cartridge) or the receiver/receiver/dryer must be replaced. After cleaning (flushing with refrigerant R1234yf) fill the refrigerant circuit with the correct quantity of refrigerant oil. Refer to TECHNICAL DATA (R1234yf SERVICING)REFRIGERANT CIRCUIT, CLEANING , (vehicle-specific repair information) and REFRIGERANT CIRCUIT / REFRIGERANT CIRCUIT (R1234yf) (vehicle-specific repair information).

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

Problem with Evaporator Vent Temperature Sensor -G263- can also cause icing-up of refrigerant circuit. For this concern also pay attention to the measured value 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 A/C COMPRESSOR (vehicle-specific repair information).

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 / REFRIGERANT CIRCUIT (R1234yf) (vehicle-specific repair information) and RADIATOR FAN -V7-, REMOVING AND INSTALLING [CNSB, CNTC] / RADIATOR FAN -V7- AND RADIATOR FAN 2 -V177-, REMOVING AND INSTALLING [CRUA, DEJA] / AUXILIARY RADIATOR, REMOVING AND INSTALLING [CNSB, CNTC, CYFB] .
  • 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 A/C COMPRESSOR .
  • 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 OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING / EXPANSION VALVE, REMOVING AND INSTALLING (vehicle-specific repair information).
  • 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 OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING / EXPANSION VALVE, REMOVING AND INSTALLING (vehicle-specific repair information).
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 (R1234yf SERVICING) (vehicle-specific repair information) and REFRIGERANT CIRCUIT / REFRIGERANT CIRCUIT (R1234yf) (vehicle-specific repair information).

Possible Deviation from Specified Value during the Pressure Test
  • The required cooling performance is obtained.
  • The high pressure pipe corresponds to the specified value
  • The low pressure is too low (lower than the target value)
Possible causes for the deviation from specified value and their solutions
  • 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 (vehicle-specific repair information). -- 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.-- If equipped check the function of the installed shut-off valves. Refer to COMPONENT LOCATION OVERVIEW - A/C SYSTEM and REFRIGERANT CIRCUIT / REFRIGERANT CIRCUIT (R1234yf) .
  • 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 OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING / EXPANSION VALVE, REMOVING AND INSTALLING (vehicle-specific repair information).
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:

For the malfunction "high pressure normal, low pressure too low" With this malfunction, evaporator may ice up, although quantity of refrigerant in circuit is OK.

If there is a malfunction on a present shut-off valve (the shut-off valve does not open) it is not necessary to clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING . For this malfunction it is sufficient to check the activation of the shut-off valve, if this is OK replace the shut-off valve.

If the problem is with the A/C Compressor Regulator Valve -N280- (regulating valve is not actuated but compressor operates nevertheless), refrigerant circuit needs to be cleaned (flush with refrigerant R1234yf). In this case, it is sufficient to replace the A/C compressor (observe quantity of refrigerant oil in A/C compressor). Refer to REFRIGERANT CIRCUIT, CLEANING .

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 low pressure drops to value in graph or below (the A/C compressor draws off refrigerant from low-pressure side). As however refrigerant cannot flow via the expansion valve, the cooling output is not always attained and high pressure may also not increase or only increase slightly due to the absence of energy conversion. For these malfunctions it is not necessary to clean the refrigerant circuit (flush with refrigerant R1234yf) it is sufficient to replace the expansion valve. Refer to REFRIGERANT CIRCUIT, CLEANING .

Check measured values of the Evaporator Vent Temperature Sensor -G263- and the actuation 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.

Possible Deviation from Specified Value During the Pressure Test
  • The A/C compressor noise (particularly after switch-on)
  • The required cooling performance is obtained.
  • High pressure normal or too high
  • The low pressure is normal or too high (the specified value is not always reached,
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.
  • Too much refrigerant or refrigerant oil in the refrigerant circuit
-- Extract refrigerant from the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, DISCHARGING .-- If the extracted refrigerant quantity is substantially greater (more than 100g (3.5 oz)) than the specified capacity. There is too much refrigerant in the refrigerant circuit. Fill the refrigerant circuit and repeat the test. Refer to TECHNICAL DATA (R1234yf SERVICING) (vehicle-specific repair information).-- If the extracted refrigerant quantity is substantially greater (more than 100g (3.5 oz)) than the specified capacity. There is too much refrigerant in the refrigerant circuit. Fill the refrigerant circuit and repeat the test. Refer to TECHNICAL DATA (R1234yf SERVICING) (vehicle-specific repair information). Clean the refrigerant circuit (flush with refrigerant R1234yf) and fill with the correct quantity of refrigerant and refrigerant oil and repeat the test. Refer to REFRIGERANT CIRCUIT, CLEANING . -- If equipped check the function of the installed shut-off valve. Refer to / REFRIGERANT SHUT-OFF VALVES (R1234yf) / REFRIGERANT CIRCUIT / REFRIGERANT CIRCUIT (R1234yf) (vehicle-specific repair information).-- Replace the expansion valve and desiccant bag/dryer cartridge (or reservoir/receiver/dryer). Refer to COMPONENTS, REPLACING and OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING / EXPANSION VALVE, REMOVING AND INSTALLING (vehicle-specific repair information).
  • A/C compressor faulty.
-- If no malfunction can be determined on a component and the extracted refrigerant quantity corresponds to the specifications, clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING . If when cleaning the refrigerant circuit no excessive amount of refrigerant oil is determined, replace the A/C compressor. Refer to COMPONENTS, REPLACING , COOLING OUTPUT, CHECKING, VEHICLES WITH AUTOMATIC CLIMATE CONTROL SYSTEM (WITH HIGH VOLTAGE SYSTEM) / COOLING OUTPUT, CHECKING / COOLING OUTPUT, CHECKING (vehicle-specific repair information) and A/C COMPRESSOR, REMOVING AND INSTALLING ON BRACKET / A/C COMPRESSOR, REMOVING AND INSTALLING / A/C COMPRESSOR (vehicle-specific repair information).
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:

This fault may also be caused by too much refrigerant oil in the refrigerant circuit. Overfilling with refrigerant oil can occur if, for example, the compressor has been replaced without adjusting the quantity of refrigerant oil. If there is too much refrigerant oil in the refrigerant circuit, clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING 

If the expansion valve (or a present shut-off valve) is faulty (constantly closed or does not open far enough), the A/C Compressor Regulator Valve -N280- is actuated to maximum output and low pressure drops to value in graph or below (the A/C compressor draws off refrigerant from low-pressure side). As the refrigerant cannot flow via the expansion valve, if the cooling output is not attained, high pressure may also not increase or only increase slightly due to the absence of energy. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for the A/C system. Refer to REFRIGERANT CIRCUIT / REFRIGERANT CIRCUIT (R1234yf) (vehicle-specific repair information).

Possible Deviation from Specified Value During the Pressure Test
  • The requested cooling output is not attained.
  • The high pressure and the low pressure corresponds to the specified value
Possible causes for the deviation from specified value and their solutions
  • 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 100g (3.5 oz) less). Refer to TECHNICAL DATA (R1234yf SERVICING) (vehicle-specific repair information), and look for leaks and correct. Refer to LEAKS, FINDING .-- If the extracted refrigerant quantity corresponds approximately to the specified capacity, the measured value of the Evaporator Vent Temperature Sensor -G263-, the activation of the A/C Compressor Regulator Valve -N280- and the function of the expansion valve is faulty or there is a malfunction on another component (see below).
  • 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 and A/C COMPRESSOR, REMOVING AND INSTALLING ON BRACKET / A/C COMPRESSOR, REMOVING AND INSTALLING / A/C COMPRESSOR (vehicle-specific repair information).
  • 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. -- Run hand over refrigerant circuit to check for differences in temperature. Refer to COOLING OUTPUT, CHECKING, VEHICLES WITH AUTOMATIC CLIMATE CONTROL SYSTEM (WITH HIGH VOLTAGE SYSTEM) / COOLING OUTPUT, CHECKING / COOLING OUTPUT, CHECKING (vehicle-specific repair information). If on a component differences in temperature is determined, because the hose or pipe are kinked or constricted, replace this component. If there is a blockage or no malfunction can be determined, clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .-- If equipped check the function of the installed shut-off valve. Refer to REFRIGERANT SHUT-OFF VALVES (R1234yf) / REFRIGERANT CIRCUIT / REFRIGERANT CIRCUIT (R1234yf) (vehicle-specific repair information).-- Replace the expansion valve and desiccant bag/dryer cartridge (or reservoir/receiver/dryer). Refer to COMPONENTS, REPLACING and OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING / EXPANSION VALVE, REMOVING AND INSTALLING (vehicle-specific repair information).
  • Too much refrigerant oil in the refrigerant circuit
-- If the extracted refrigerant quantity meets the specified capacity is only slightly smaller than the specified capacity (maximum 100g (3.5 oz)) too much refrigerant oil is in the refrigerant circuit. Refer to TECHNICAL DATA (R1234yf SERVICING) (vehicle-specific repair information). Clean the refrigerant circuit (flush with refrigerant R1234yf) and fill with the correct quantity of refrigerant and refrigerant oil and repeat the test. Refer to REFRIGERANT CIRCUIT, CLEANING . -- If equipped check the function of the installed shut-off valve. Refer to REFRIGERANT SHUT-OFF VALVES (R1234yf) / REFRIGERANT CIRCUIT / REFRIGERANT CIRCUIT (R1234yf) (vehicle-specific repair information).-- Replace the expansion valve and desiccant bag/dryer cartridge (or reservoir/receiver/dryer). Refer to COMPONENTS, REPLACING and EXPANSION VALVE, REMOVING AND INSTALLING / OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING (vehicle-specific repair information).
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 measured value of Evaporator Vent Temperature Sensor -G263- is incorrect, evaporator may ice up or cooling output is not attained use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function for the A/C system, Refer to COMPONENT LOCATION OVERVIEW - A/C SYSTEM (vehicle-specific repair information).

Overfilling with refrigerant oil can occur if, for example, the compressor has been replaced without adjusting the quantity of refrigerant oil.

If expansion valve is malfunctioning (permanently open), evaporator temperature is no longer regulated such that only refrigerant in gaseous state exits from the evaporator. Under certain usage conditions, liquid droplets may then be drawn in by the compressor and cause noise (liquid cannot be compressed).

If too much refrigerant oil is located in the circuit, the A/C compressor must be discharges and if equipped replace the receiver/receiver/dryer (or dryer cartridge). Refer to REFRIGERANT CIRCUIT, DISCHARGING (R1234yf)  / OVERVIEW - CONDENSER, A/C COMPRESSOR, REFRIGERANT LINES AND EXPANSION VALVE / CONDENSER, REMOVING AND INSTALLING (vehicle-specific repair information). After cleaning the refrigerant circuit (flushing with refrigerant R1234yf) and fill it with the correct quantity of refrigerant oil in the circuit. Refer to REFRIGERANT CIRCUIT, CLEANING  and REFRIGERANT CIRCUIT, CHARGING (R1234yf)  / TECHNICAL DATA (R1234yf SERVICING) (vehicle-specific repair information).