Refrigerant Circuit, Servicing
Refrigerant Circuit, Servicing
• No refrigerant must be added into the refrigerant circuit (discharge, evacuate and recharge refrigerant circuit).
• Compressor is always driven when engine is running; there is no magnetic clutch. Engine is therefore not to be started unless refrigerant circuit has been properly assembled. For example; if the refrigerant lines are not connected to A/C compressor, when the engine is running the A/C compressor may heat up (via internal heat generation) so much that the A/C compressor will be damaged. Such internal heat generation results from the fact that - even with delivery near 0% - the compressor is confronted with a fixed resistance (sealed circuit).
• To stop the A/C compressor being destroyed when the refrigerant circuit is empty, it is designed such that delivery is reduced to roughly 0% and lubrication is maintained by way of an internal oil circuit with the oil left in the A/C compressor.
• The entire amount of refrigerant oil to be added to the refrigerant circuit is in the replacement compressor.
• Different refrigerant oils are required for A/C compressors made by Denso, Sanden and Zexel/Valeo, refer to => Electronic Parts Catalog.
• Coat the O-ring with refrigerant oil before installing, refer to => [ Refrigerant Circuit O-rings ] Refrigerant Circuit O-rings.
• The specified diameters for O-rings and the tightening torque pertain also to the threaded connections of the refrigerant lines or refrigerant hoses between the separate components.
• Only install O-rings that have been approved to be used with refrigerant R134a. Refer to => [ Refrigerant Circuit O-rings ] Refrigerant Circuit O-rings.
• Check cooling performance, refer to => [ A/C Unit, Checking Cooling Output ] A/C Unit, Checking Cooling Output.
• Check pressures in refrigerant circuit.
• All refrigerant circuit servicing and test procedures not described in this repair information are covered in => Refrigerant
R134a Servicing.
• Operate the A/C system after filling the refrigerant circuit according to => [ A/C System Operating After Filling Refrigerant Circuit ] A/C System Operating After Filling Refrigerant Circuit.
HD = High-pressure end
ND = Low-pressure end
1 A/C Compressor Regulator Valve (N280)
• 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 is activated by the Climatronic control module (J255) , via the vehicle electrical system control module (J519). The A/C compressor regulator valve controls the pressure on the refrigerant circuit low pressure side. Check using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.
2 A/C Compressor
• Removing from bracket, refer to => [ A/C Compressor From Bracket ] A/C Compressor from Bracket
• A/C compressor refrigerant line, disconnecting and reconnecting, refer to => [ Refrigerant Circuit Components ] Refrigerant Circuit Components.
• When installing refrigerant lines/hoses and pertaining bracket, make sure there is a sufficient gap between belt, bracket and belt pulley.
• To protect the A/C compressor, the engine should only be started with the refrigerant circuit completely assembled.
• Remove ribbed belt.
• For 6 cylinders gas engine or 8-cylinder FSI / TFSI engine, the A/C compressor can only be removed from the bracket if the refrigerant circuit has been discharged. Refer to 6 cylinder=> [ Compressor ] Compressor, or 8 cylinder FSI => [ Compressor ] Compressor or 8 cylinder TFSI=> [ Compressor ] Compressor.
• For 12 cylinders engine, the A/C compressor can only be removed from the bracket if the refrigerant circuit has been discharged. Refer to => [ A/C Compressor from Bracket ] A/C Compressor from Bracket.
• At the start of production, the A/C compressors manufactured by "Denso" (type "6 SEU 14") were installed. Compressors from other manufacturers may also be installed at a later time.
• Depending on time period of production and on the engine, the 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.
• Depending on A/C compressor type and the design of the refrigerant circuit (one or two evaporators), different refrigerant oil and refrigerant capacities can be designated for the refrigerant circuit.
• 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 A/C Compressor Belt Pulley /Drive Unit
• Compressor belt pulley on 6 cylinder and 12 cylinder engines, refer to => [ A/C Compressor Belt Pulley ] Service and Repair.
• Ribbed belt-allocation, refer to Electronic Parts Catalog.
• Replace the A/C compressor drive unit (vehicles with an 8 cylinder FSI / TFSI engine), refer to => [ A/C Compressor Drive Unit ] A/C Compressor Drive Unit, 8 cylinder FSI => [ Compressor ] Compressor or 8 cylinder TFSI => [ Compressor ] Compressor.
• 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 runs 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 Electronic Parts Catalog.
4 Oil Drain Plug
• Denso compressor tightening torque 30 Nm.
• Denso A/C compressors have sealing ring installed, always replace
• 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 In Refrigerant Line
• Depending on the version of the vehicle and the engine, these connection points may be present at different locations on the refrigerant lines.
• Bolts of the connection points must only be loosened when refrigerant circuit has been discharged.
7 Connection With Valve
• With the refrigerant circuit empty, use an adapter from the Socket for A/C Valves (T10364) to remove and install a valve insert.
The valve insert may be removed only when the refrigerant circuit is empty.
8 A/C Pressure/Temperature Sensor (G395) 1)
• Removing and installing, refer to => [ A/C Pressure/Temperature Sensor (G395) ] A/C Pressure/Temperature Sensor (G395).
• To check the signal use the Vehicle Diagnostic Tester in the "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). A high pressure sensor (G65) cannot be installed on this vehicle (it only delivers square-wave signals). Refer to the Electronic Parts Catalog.
• The temperature measured by the A/C Pressure/Temperature Sensor differs from the actual refrigerant temperature in the refrigerant circuit because of the version of the A/C Pressure/Temperature Sensor and its installation location. Because of this, it is not currently evaluated and is not used to regulate the A/C system.
9 Condenser (With Fluid Reservoir)
• Removal and installation, refer to => [ Condenser Refrigerant Lines ] Condenser Refrigerant Lines.
• Removal and installation, refer to => [ Condenser ] Condenser.
• Different versions, refer to the Electronic Parts Catalog.
10 Fluid Reservoir (of the Condenser With Dryer Cartridge)
• Fluid reservoir is a component of the condenser.
• Removal and installation, refer to => [ Dryer Cartridge ] Dryer Cartridge.
• Different versions, refer to the Electronic Parts Catalog.
• The dryer cartridge may be removed only when the refrigerant circuit is empty.
11 Refrigerant Line Quick-Release Coupling - Low Pressure Side
• Installed in the area under the left headlamp.
The quick-release couplings may be unlocked and opened only if the refrigerant circuit is empty.
• Removal and installation, 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 the Electronic Parts Catalog.
12 Refrigerant Line Quick-Release Coupling - High Pressure Side
• Installed in the area under the left headlamp.
The quick-release coupling connectors may be unlocked and opened only if the refrigerant circuit is empty.
• Removal and installation, 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 Electronic Parts Catalog.
13 Refrigerant Pipe With Inner Heat Exchanger
• In this refrigerant pipe, the flowing fluid warm refrigerant on the high pressure side is delivered into the low pressure side as flowing, vapor, cold refrigerant to increase the efficiency of the A/C system.
• Removal and installation, refer to => [ Refrigerant Lines With Inner Heat Exchanger ] Refrigerant Lines With Inner Heat Exchanger.
14 Refrigerant Line Quick-Release Coupling - Low Pressure Side
• Installed in the area of the A-pillar under the left fender.
The quick-release couplings may be unlocked and opened only if the refrigerant circuit is empty.
• Removal and installation, 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 Electronic Parts Catalog.
15 Refrigerant Line Quick-Release Coupling - High Pressure Side
• Installed in the area of the A-pillar under the left fender.
The quick-release coupling connectors may be unlocked and opened only if the refrigerant circuit is empty.
• Removal and installation, 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 Electronic Parts Catalog.
16 Sealing Cap
• With a seal.
• Always screw on.
17 Low Pressure Side Service Connection
• The service connection is installed in the plenum chamber under a door in the plenum chamber cover.
Only remove service connections when the refrigerant circuit is empty. The connection does not have a valve.
• Different versions (with primary sealing valve or with Schrader valve) depending on refrigerant line.
• To remove and install the service connection or the valve insert with the refrigerant circuit empty, use, for example, an adapter from the Socket for A/C Valves (T10364).
18 High Pressure Side Service Connection
• The service connection is installed in the plenum chamber under a door in the plenum chamber cover.
Only remove service connections when the refrigerant circuit is empty. The connection does not have a valve.
• To remove and install the service connection or the valve insert with the refrigerant circuit empty, use, for example, an adapter from the Socket for A/C Valves (T10364).
19 Sealing Cap
• With a seal.
• Always screw on.
20 Front Expansion Valve
• For the evaporator in the front A/C unit (A/C unit installed under the instrument panel, in the plenum chamber).
• Removal and installation, refer to => [ Front Expansion Valve Refrigerant Lines, Disconnecting ] Front Expansion Valve Refrigerant Lines, Disconnecting.
• Removal and installation, refer to => [ Front Expansion Valve ] Front 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.
21 Evaporator
• Evaporator in front A/C unit (installed under instrument panel).
• A/C unit (with evaporator) removing and installing, refer to => [ Front Heating and A/C Unit ] Front Heating and A/C Unit.
• Removal and installation, refer to => [ Front Evaporator With A/C Unit Installed ] Front Evaporator With A/C Unit Installed.
• The evaporator is currently not available as a replacement part for all versions, therefore check in advance, whether this evaporator is available as a replacement evaporator. Refer to Electronic Parts Catalog (ETKA). If the evaporator is not available as a replacement evaporator, the A/C unit must be removed. Refer to=> [ Front Heating and A/C Unit ] Front Heating and A/C Unit and the evaporator housing with the series evaporator must be replaced entirely, refer to => [ Front Evaporator Housing ] Front Evaporator Housing.
22 Connection Of Refrigerant Line to Evaporator In Rear Heating and A/C Unit
• Only Present On Vehicles With A Rear Heating & A/C Unit (Optional Equipment).
• High Pressure Side.
• Bolts of the connection points must only be loosened when refrigerant circuit has been discharged.
• Disconnect the connection between the refrigerant lines and the front and rear expansion valves, refer to => [ Connection Points Of Refrigerant Lines, Loosening and Assembling ] Connection Points Of Refrigerant Lines, Loosening and Assembling.
• Removal and installation, refer to => [ Rear A/C Unit Expansion Valve To Evaporator Refrigerant Lines, Replacement ] Rear A/C Unit Expansion Valve To Evaporator Refrigerant Lines, Replacement.
• Removal and installation, refer to => [ Rear Expansion Valve To Connection Point Refrigerant Lines, Replacement ] Rear Expansion Valve To Connection Point Refrigerant Lines, Replacement.
23 Connection in Refrigerant Line to Evaporator In Rear Heating and A/C Unit
• Only present on vehicles with a rear heating & A/C unit (optional equipment).
• Bolts of the connection points must only be loosened when refrigerant circuit has been discharged.
• Disconnect the connection between the refrigerant lines and the front and rear expansion valves, refer to => [ Connection Points Of Refrigerant Lines, Loosening and Assembling ] Connection Points Of Refrigerant Lines, Loosening and Assembling.
24 Rear Expansion Valve
• Only present in vehicles with a rear A/C unit (optional equipment).
• For the evaporator in the rear A/C unit (installed on the underbody of the vehicle in the area of the center tunnel).
• Removal and installation, refer to => [ Rear Expansion Valve ] Rear Expansion Valve
• Ensure the correct allocation, refer to the Electronic Parts Catalog.
• Check the function, refer to => [ A/C Unit, Checking Cooling Output ] A/C Unit, Checking Cooling Output.
• After the A/C compressor is switched off in this vehicle, it may take a relatively long time for the pressure on the high pressure side to decrease (the expansion valve(s) is/are cold, the pressure on the low pressure side increases quickly after deactivation, the expansion valve(s) closes/close and the refrigerant can only flow slowly to the low pressure side).
• Removal and installation, refer to => [ Rear Expansion Valve To Connection Point Refrigerant Lines, Replacement ] Rear Expansion Valve To Connection Point Refrigerant Lines, Replacement.
• Removal and installation, refer to => [ Rear A/C Unit Expansion Valve To Evaporator Refrigerant Lines, Replacement ] Rear A/C Unit Expansion Valve To Evaporator Refrigerant Lines, Replacement.
25 Rear Evaporator
• Only present in vehicles with a rear A/C unit (optional equipment).
• Removal and installation, refer to => [ Rear Evaporator Replacement ] Rear Evaporator Replacement.
• Removal and installation, refer to => [ Rear Heating and A/C Unit ] Rear Heating and A/C Unit.
• Disassembly, refer to => [ Disassembly Of Rear A/C Unit ] Disassembly Of Rear A/C Unit.
• The evaporator is installed in the rear A/C unit (the A/C unit is installed in the center console).
• The evaporator can be replaced only with the A/C unit removed.
• Removal and installation, refer to => [ Rear Expansion Valve To Connection Point Refrigerant Lines, Replacement ] Rear Expansion Valve To Connection Point Refrigerant Lines, Replacement.
• Removal and installation, refer to => [ Rear A/C Unit Expansion Valve To Evaporator Refrigerant Lines, Replacement ] Rear A/C Unit Expansion Valve To Evaporator Refrigerant Lines, Replacement.