Refrigerant Circuit Component Overview
Refrigerant Circuit Component Overview
HD = High-pressure end
ND = Low-pressure end
Arrows point in direction of refrigerant flow.
The parts identified with 1) can be serviced or replaced by any workshop. The work procedures identified with 1) can be performed by any workshop. These components and work procedures do not affect the refrigerant circuit.
Refrigerant circuit components not identified with 1) cannot be serviced or replaced by all workshops. This also applies to all refrigerant hoses and refrigerant lines. Components not identified with 1) can only be serviced or replaced by a workshop that has all the necessary equipment and tools. In these workshops only trained technicians may perform this work. The refrigerant circuit must be drained.
1 A/C Compressor Regulator Valve (N280)
• Do not remove
• Checking activation and function, refer to => [ A/C Compressor Regulator Valve (N280), Checking Switch-On Signal ] A/C Compressor Regulator Valve (N280), Checking Switch-On Signal 1).
• The A/C compressor regulator valve (N280) is actuated by the Climatronic control module (J255) display and control head via the vehicle electrical system control module (J519). The A/C compressor regulator valve (N280) controls the pressure on the refrigerant circuit low pressure side. Refer to Vehicle Diagnostic Tester under "Guided Fault Finding".
2 A/C Compressor
• A/C compressor refrigerant line, disconnecting and reconnecting, refer to => [ Refrigerant Circuit Components ] Refrigerant Circuit Components.
• Remove the ribbed belt.
• A/C compressor, removing and installing, refer to => [ A/C Compressor ] A/C Compressor.
• When installing the refrigerant pipes and mounts, make sure there is enough space between the belt, the bracket, the belt pulley and the refrigerant pipes.
• To protect the A/C compressor, the engine should only be started with the refrigerant circuit completely assembled.
• For vehicles with 6 cylinder FSI engine, the A/C compressor may be dismantled and removed from the mount only when the refrigerant circuit is open. The A/C compressor can be removed from the bracket only when the refrigerant circuit has been evacuated on an 8 cylinder FSI engine. Refer to => [ A/C Compressor ] A/C Compressor.
• At start of production, A/C compressors manufactured by "Denso" (type "6 SEU 14") on 4 and 6 cylinder engines and type "7 SEU 17" on vehicles with 8 cylinders FSI engine) installed. Compressors from other manufacturers may also be installed at a later time. Refer to Electronic Parts Catalog (ETKA).
• Depending on time period of production and on engine, compressor construction type may vary. Refer to Electronic Parts Catalog (ETKA).
• These A/C compressors are available as replacement parts with different oil fill capacities. Therefore, note the capacity on the A/C compressor and the exact part number. Refer to Electronic Parts Catalog (ETKA).
• Depending on A/C compressor type, different refrigerant oil fill capacities may be designated for the refrigerant circuit. The reason for the different oil capacities in the A/C compressor for an otherwise identical refrigerant circuit is the design of the compressor. Observe these oil capacities. Too much oil in the refrigerant circuit increases the pressures and reduces the cooling output of the A/C system. Too little oil can result in lubrication problems in the A/C compressor.
• When installing the refrigerant lines and the corresponding brackets, make sure there is adequate distance between the belt, bracket and belt pulley.
• An A/C compressor with an A/C clutch (N25) is installed as a running change on certain 4 cylinder vehicles from MY 12. The A/C clutch turns off the A/C compressor drive completely under certain conditions (for example "ECON"). The correct Climatronic control module (J255) must be installed and it must be coded correctly so that the Climatronic control module display and control unit can control the A/C clutch (N25). Refer to the Parts Catalog and to Vehicle Diagnostic Tester under "Guided Fault Finding".
• If a new compressor has been installed or new refrigerant oil has been put into the A/C compressor (for example after blowing through the A/C system), the A/C compressor must be turned by hand approximately 10 turns. This ensures that the compressor is not damaged when activated.
3 Belt Pulley/ A/C Compressor Drive Unit / A/C Clutch Belt Pulley (N25)
• A/C compressor belt pulley, removing and installing applies to 4- and 6 cylinder vehicles 1). Refer to => [ A/C Compressor Belt Pulley ] A/C Compressor Belt Pulley.
• Ribbed belt, removing and installing applies to 4- and 6 cylinder engines 1).
• Ribbed belt allocation (vehicles with 4- and 6 cylinder engine), refer to Electronic Parts Catalog (ETKA).
• A/C Compressor drive, removing and installing, 8 Cylinder FSI Engine, refer to => [ A/C Compressor Drive Unit Overview ] A/C Compressor Drive Unit Overview (A/C compressor, removing, refer to RS => [ A/C Compressor ] A/C Compressor or RS5 => [ A/C Compressor ] A/C Compressor).
• A/C Clutch (N25) belt pulley, replacing. applies to certain 4 cylinder engines from MY 12 1). Refer to => [ Belt Pulley with A/C Clutch (N25) Overview ] Belt Pulley With A/C Clutch (N25) Overview.
• There is an overload protection installed between the belt pulley and the A/C compressor input shaft to protect the belt should the A/C compressor get blocked or be difficult to move.
• If the A/C compressor is run with resistance, the overload safeguard interrupts the supply of power to it.
• Rubber elements are installed between belt pulley/drive unit and the A/C compressor driveshaft, vibrations which may occur during A/C compressor operation may be dissipated via these rubber elements (damper function at torque fluctuations).
• Different versions of the pulley are installed depending on the type of A/C compressor and engine, refer to the Parts Catalog and => [ A/C Compressor Belt Pulley ] A/C Compressor Belt Pulley.
• An A/C compressor with an A/C clutch (N25) is installed as a running change on certain 4 cylinder vehicles from MY 12. The A/C clutch turns off the A/C compressor drive completely under certain conditions (for example "ECON"). The correct Climatronic control module (J255) must be installed and it must be coded correctly so that the Climatronic control module display and control unit can control the A/C clutch (N25). Refer to the Parts Catalog and to the Vehicle Diagnostic Tester under "Guided Fault Finding".
4 Oil Drain Plug
• "Denso" A/C compressors have sealing ring installed, always replace.
• "Denso" compressor tightening torque 30 Nm.
• May only be removed to drain refrigerant oil with A/C compressor removed, (rotate the A/C compressor via belt pulley to accelerate refrigerant oil flowing out).
5 Pressure Relief Valve
• Do not remove
• Tightening specification for the " Denso" A/C compressor: 10 Nm
• With O-ring "Denso" A/C compressor 8.5 mm x 1.75 mm, refer to => [ Refrigerant Circuit O-rings ] Refrigerant Circuit O-Rings.
6 Connection With Valve
• For removing and installing the valve set when the refrigerant circuit is evacuated, for example, use an adapter from the socket for A/C valves (T10364).
The valve insert may be removed only when the refrigerant circuit is empty.
7 A/C Pressure/Temperature Sensor (G395) 1)
• Removing and installing, refer to => [ A/C Pressure/Temperature Sensor (G395) ] Service and Repair.
• Check the signal using the Vehicle Diagnostic Tester in "Guided Fault Finding" function.
• The A/C pressure/temperature sensor exchanges information with the vehicle electrical system control module (J519) via a local Data bus. The vehicle electrical system control module transmits the data via the Data bus to the Climatronic control module (J255) display and control head. A high pressure sensor (G65) cannot be installed on this vehicle (it only delivers square-wave signals). Refer to Electronic Parts Catalog (ETKA).
• The temperature measured by the A/C pressure/temperature sensor differs from the actual refrigerant temperature in the refrigerant circuit because of the A/C pressure/temperature sensor design and its component location. Because of this, it is not currently evaluated and is not used to regulate the A/C system.
8 Condenser
• Refrigerant lines, disconnecting and reconnecting, refer to => [ Refrigerant Circuit Components ] Refrigerant Circuit Components.
• Condenser, removing and installing, refer to=> [ Refrigerant Circuit Components ] Refrigerant Circuit Components.
• Different versions. Refer to Electronic Parts Catalog (ETKA).
• It may be necessary to evacuate the refrigerant circuit and remove the refrigerant pipes from the condenser in order to remove the condenser from the front end or to remove the radiator depending on the version of the radiator and the condenser (for example, on the Audi RS 4 and the Audi RS 5). Refer to => [ Refrigerant Circuit Components ] Refrigerant Circuit Components.
9 Fluid Reservoir
• The receiver is mounted directly on the condenser. Refer to => [ Fluid Reservoir ] Fluid Reservoir.
• Removing and installing, refer to => [ Fluid Reservoir ] Fluid Reservoir.
• Different versions. Refer to Electronic Parts Catalog (ETKA).
• The reservoir may be attached to or integrated in the condenser, depending on the version of the condenser. Refer to => [ Fluid Reservoir ] Fluid Reservoir and => [ Refrigerant Circuit Components ] Refrigerant Circuit Components.
• Dryer cartridge (on a condenser with an integrated fluid reservoir), removing and installing, refer to => [ Refrigerant Circuit Components ] Refrigerant Circuit Components.
10 Refrigerant Line Quick-Release Coupling - High Pressure Side
The quick acting coupling connectors may be unlocked and opened only if the refrigerant circuit is empty.
• Disconnecting and connect the refrigerant lines from the quick acting coupling connectors, refer to => [ Refrigerant Lines Disconnecting from Quick-Release Couplings and Connecting ] Refrigerant Lines Disconnecting From Quick-Release Couplings and Connecting.
• Replace the quick-release coupling completely with the O-ring and support ring. Refer to => [ Refrigerant Lines Disconnecting from Quick-Release Couplings and Connecting ] Refrigerant Lines Disconnecting From Quick-Release Couplings and Connecting, and to the Parts Catalog.
• The Audi RS 4 and on the Audi RS 5 has a block connector instead of quick-release connector. Removing and installing the block connector is same as removing and installing the block connector on the condenser. Refer to => [ Refrigerant Circuit Components ] Refrigerant Circuit Components.
11 Sealing Cap
• With a seal
• Always screw on
12 High Pressure Side Service Connection
• For removing and installing the service connection or the valve set when the refrigerant circuit is evacuated, for example, use an adapter from the socket for A/C valves (T10364).
• For the A/C service station to measure pressures, to discharge and recharge the refrigerant circuit.
• Depending on engine version, it may be necessary to remove some components in order to be able to connect to service coupling of the service station.
Only remove service connections when the refrigerant circuit is empty. The connection does not have a valve.
• Depending on the allocation of the service connection an on the refrigerant line, and on the version of the vehicle, it may be necessary to remove the additional reinforcement on the left suspension strut dome so that the service coupling of the service station can be connected (for example, on the Audi Q5).
• Depending on the version of the vehicle, Service connections may be connected to the connected refrigerant pipe (for example, on the Audi RS 4 and Audi RS 5) instead of to the refrigerant pipe with an inner heat exchanger.
• It may be necessary on the Audi RS 4 and the Audi RS 5 to carefully lift the refrigerant pipe and then push it slightly to the side in order to connect the Service coupling.
13 Refrigerant Pipe With Inner Heat Exchanger
• In this refrigerant line, liquid warm refrigerant from the high pressure side is released into the low pressure side as flowing vaporous refrigerant energy. This increases the cooing efficiency of the A/C system.
• Removing and installing, refer to => [ Refrigerant Circuit Components ] Refrigerant Circuit Components.
14 Expansion Valve
• Refrigerant lines with inner heat exchanger, disconnecting and reconnecting, refer to => [ Refrigerant Circuit Components ] Refrigerant Circuit Components.
• Removing and installing, refer to => [ Expansion Valve ] Expansion Valve.
• After switching off the A/C compressor in this vehicle, it may take a relatively long time for the pressure on the high pressure side to decrease. This is because the expansion valve is cold and the pressure on the low pressure side increases quickly after shutting the compressor off, then the expansion valve closes and the refrigerant flows slowly to the low pressure side. If the A/C compressor is switched on, the pressure on the low pressure side goes down, the expansion valve open and the refrigerant can flow of the low pressure side.
• From the start of production through the change-over from MY 12, evaporators approximately 40 mm (1.6 in.) wide (block depth) are being installed (air conditioner part number "8K_ 820 005"). From MY 12, as a running change and depending on the version of the vehicle, an approximately 50 mm (2 in.) wide evaporator (block depth) is being installed (air conditioner part number "8T_ 820 005"). Pay attention to the correct allocation of the evaporator expansion valve (there are different versions). Refer to the Parts Catalog.
15 Evaporator
• A/C unit (with evaporator) removing and installing, refer to => [ A/C Unit ] A/C Unit.
• Evaporator with the A/C installed, removing and installing, refer to => [ Evaporator, A/C Unit Installed ] Evaporator, A/C Unit Installed.
• From the start of production through the change-over from MY 12, evaporators approximately 40 mm (1.6 in.) wide (block depth) are being installed (air conditioner part number "8K_ 820 005"). From MY 12, as a running change and depending on the version of the vehicle, an approximately 50 mm (2 in.) wide evaporator (block depth) is being installed (air conditioner part number "8T_ 820 005"). Pay attention to the correct allocation of the evaporator expansion valve (there are different versions). Refer to the Parts Catalog.
16 Refrigerant Line Quick Acting Coupling - Low Pressure Side
The quick acting coupling connectors may be unlocked and opened only if the refrigerant circuit is empty.
• Disconnecting and connect the refrigerant lines from the quick acting coupling connectors, refer to => [ Refrigerant Lines Disconnecting from Quick-Release Couplings and Connecting ] Refrigerant Lines Disconnecting From Quick-Release Couplings and Connecting.
• Replace the quick-release coupling completely with the O-ring and support ring. Refer to => [ Refrigerant Lines Disconnecting from Quick-Release Couplings and Connecting ] Refrigerant Lines Disconnecting From Quick-Release Couplings and Connecting, and to the Parts Catalog.
17 Sealing Cap
• With a seal
• Always screw on
18 Low Pressure Side Service Connection
• For removing and installing the service connection or the valve set when the refrigerant circuit is evacuated, for example, use an adapter from the socket for A/C valves (T10364).
• Depending on engine version, it may be necessary to remove some components in order to be able to connect to service coupling of the service station.
Only remove service connections when the refrigerant circuit is empty. The connection does not have a valve.
• Depending on the allocation of the service connection an on the refrigerant line, and on the version of the vehicle, it may be necessary to remove the additional reinforcement on the left suspension strut dome so that the service coupling of the service station can be connected (for example, on the Audi Q5).
• Depending on the version of the vehicle, Service connections may be connected to the connected refrigerant pipe (for example, on the Audi RS 4 and Audi RS 5) instead of to the refrigerant pipe with an inner heat exchanger.