Refrigerant Circuit
Refrigerant Circuit
• 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. If, for example, the refrigerant lines are not connected to the compressor and the engine is running, the compressor could be destroyed by the build-up of internal heat. Such internal heat generation results from the fact that - even with delivery approaching 0 % - the compressor is confronted with a fixed resistance (sealed circuit).
• To stop the 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 compressor.
• Replacement compressors contain the full quantity of refrigerant oil required for the refrigerant circuit.
• Zexel, Sanden and Denso compressors require different refrigerant oils.
• Coat O-ring seals lightly with refrigerant oil before installing => [ Refrigerant Circuit O-Ring Seals ] Refrigerant Circuit O-Ring Seals.
• The specified diameters for O-ring seals and the tightening torques pertain also to the threaded connections of the refrigerant lines or hoses between the separate components.
• Only install O-rings that are approved for use with refrigerant R134a.
• A/C system cooling performance, checking => [ A/C Unit, Checking Cooling Output ] A/C Unit, Checking Cooling Output
• Check pressures in refrigerant circuit.
HD = High-pressure end
ND = Low-pressure end
1 A/C Compressor Regulator Valve (N280)
• Checking activation and function => [ A/C Compressor Regulator Valve, Checking Activation Signal ] Testing and Inspection.
• Do not remove
• A/C Compressor Regulator Valve (N280) is activated by the Climatronic Control Module (J255) A/C control head, it controls pressure on the low pressure side of refrigerant circuit
2 Compressor
• Different versions (depending on the engine)
• Removing the compressor from the holder and reinstalling => [ Compressor with Pulley, Removing and Installing at Bracket ] Compressor with Pulley, Removing and Installing at Bracket
• Removing the compressor with drive unit (shaft) from the holder and reinstalling => [ Compressor, 8-Cylinder ]
• Refrigerant line, disconnecting from compressor and connecting => [ Refrigerant Lines, Disconnecting and Connecting at Compressor ] Refrigerant Lines, Disconnecting and Connecting at Compressor
• Remove ribbed belt
• Compressor, Removing and Installing (6 cylinder) => [ Compressor, 6-Cylinder ] Compressor, 6-Cylinder
• Compressor, Removing and Installing, (8 cylinder) => [ Compressor, 8-Cylinder ]
• Compressor, Removing and Installing, (10 cylinder) => [ Compressor, 10-Cylinder ]
• To protect the compressor, the engine should only be started with the refrigerant circuit completely assembled.
• When installing refrigerant lines/hoses and pertaining bracket, make sure there is a sufficient gap between belt, bracket and belt pulley
• After installing the compressor and before positioning the belt or tightening the driveshaft, manually turn the compressor approx. 10 rotations (to prevent damage at the compressor). Rotating forces refrigerant oil out of the compression chamber if it has accumulated there in the removed compressor or after adding fresh refrigerant oil (e.g. after flushing the refrigerant circuit).
3 Compressor Belt Pulley/Drive Unit
• Different versions (depending on engine)
• Replacing compressor pulley.
• Ribbed belt, removing and installing
• Compressor Drive Unit, Replacing => [ Compressor Drive Unit ] Compressor Drive Unit
• An overload safeguard is installed between the belt pulley/drive unit and driveshaft, this protects the compressor belt / engine in the event that the compressor is seized or does not move freely.
• If compressor is runs with resistance, overload safeguard interrupts power transmission to compressor.
• Rubber elements are installed between belt pulley/drive unit and compressor driveshaft, vibrations which may occur during compressor operation may be dissipated via these rubber elements (damper function at torque fluctuations).
4 Oil Drain Plug
• Denso compressors have a sealing ring installed, always replace.
• Tightening specification: 30 Nm
• Should only be unscrewed to drain refrigerant oil and with the compressor removed. Turn compressor via belt pulley/drive unit to speed up refrigerant oil drainage.
5 High Pressure Relief Valve
• Do not remove
• Tightening specification: 10 Nm
6 Condenser
• Refrigerant lines, disconnecting and reconnecting => [ Refrigerant Lines, Disconnecting from Condenser and Connecting ] Refrigerant Lines, Disconnecting from Condenser and Connecting
• Condenser, removing and installing => [ Condenser ] Condenser
• Different versions
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.
CAUTION!
The valve insert may be removed only when the refrigerant circuit is empty.
8 A/C Pressure/Temperature Sensor (G395)
• Removing and installing => [ A/C Pressure/Temperature Sensor ] A/C Pressure/Temperature Sensor
• Housing color: "gray"
• The A/C Pressure/Temperature Sensor (G395) measured values can be read out in two display groups via the "read measured values block" function
• The A/C Pressure/Temperature Sensor (G395) exchanges information with the Climatronic Control Module (J255) via the "Lin Bus" A/C data bus system. A high pressure sensor (G65) cannot be installed on the Audi A6 (it only delivers square-wave signals).
• The temperature measured by the A/C Pressure/Temperature Sensor (G395) differs from the actual refrigerant temperature in the refrigerant circuit because of the A/C Pressure/Temperature Sensor (G395) design and its component location. Because of this, it is not currently evaluated and is not used to regulate the A/C system.
9 Service Connection
• High pressure side
• 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).
CAUTION!
Only remove service connections when the refrigerant circuit is empty. The connection does not have a valve.
10 Cap
• With seal
• Always screw on
11 Union In Refrigerant Pipe (with Restrictor)
• Replacing the O-ring seal
• Tightening specification: 15 Nm
• The threaded connection may be opened only when the refrigerant circuit is empty.
12 Restrictor
• Installed in the threaded connection => [ (Item 11) Union In Refrigerant Pipe (with Restrictor) ].
• O-ring seal: 7.5 mm/1.5 mm
• Replace the restrictor with the O-ring seal.
• Removing and installing => [ Restrictor ] Restrictor
• Coat O-ring lightly with refrigerant oil before installing
13 Refrigerant Line Threaded Connection at A/C Unit
• The threaded connection may only be open when refrigerant circuit is empty.
• Refrigerant Line to A/C Unit, => [ Refrigerant Lines at A/C Unit ] Refrigerant Lines at A/C Unit.
14 Refrigerant Line Threaded Connection (at Evaporator)
• Removing and installing the threaded connection => [ Evaporator ] Service and Repair.
• Tightening specification: 25 Nm
• The threaded connection may only be open when refrigerant circuit is empty.
15 Evaporator
• Removing and installing the evaporator => [ Evaporator ] Service and Repair.
• Replace the O-ring seals
• Refrigerant Line to A/C Unit, Removing and Installing => [ Refrigerant Lines at A/C Unit ] Refrigerant Lines at A/C Unit
16 Service Connection
• Low pressure side
• 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).
CAUTION!
Only remove service connections when the refrigerant circuit is empty. The connection does not have a valve.
17 Cap
• With seal
• Always screw on
18 Reservoir
• Different versions
• Replace the O-ring seals
• Coat the O-ring seals lightly with refrigerant oil before installing.
• Tightening specification of bolt at block connection: 10 Nm
• Removing and installing => [ Reservoir ] Service and Repair