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. If for example the refrigerant lines are not connected to the compressor and the engine is started then the compressor may 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.
• For compressors manufactured by "Zexel", "Sanden ", and "Denso", various refrigerant oils are required.
• The specified diameters for O-rings 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 seals that are approved for Refrigerant R134a.
• Check cooling performance. Refer to => [ A/C Unit, Checking Cooling Output ] A/C Unit, Checking Cooling Output.
• Checking pressures in refrigerant circuit. Refer to =>
Heating and Air Conditioning Heating and Air Conditioning
• All other servicing and testing work not described in this repair information.
Refrigerant Circuit, Servicing
HD = High-pressure end
ND = Low-pressure end
1 - A/C Compressor Regulator Valve (N280)
• Do not remove
• Checking activation and function. Refer to => [ Test Step 6 ] Climatronic Control Module A/C Control Head Electrical Test.
• A/C Compressor Regulator Valve (N280) is activated by A/C control head Climatronic Control Module ( J255), it controls pressure on low pressure side of refrigerant circuit
2 - Compressor
• Refrigerant line, disconnecting from compressor and connecting. Refer to => [ Refrigerant Lines, Disconnecting and Connecting from Compressor ] Refrigerant Lines, Disconnecting and Connecting From Compressor
• Replace the O-ring seals to the connections.
• To protect the compressor, the engine should only be started with the refrigerant circuit completely assembled.
• Remove ribbed belt.
• Compressor, removing and installing, refer to => [ Compressor, 4- or 6-Cylinder ] Compressor, 4- or 6-Cylinder
• Different compressors, depending on the country version and the engine. Refer to => [ Refrigerant Circuit ] Refrigerant Circuit
• In vehicles with an 8 cylinder engine, the compressor is driven by a drive shaft not a belt. Refer to => [ Compressor Drive Unit ] Compressor Drive Unit
• After installing a new compressor or pouring in fresh refrigerant oil (e.g. after blowing out the refrigerant circuit), crank the compressor 10 times by hand following installation and prior to initial start-up in order to prevent compressor damage
3 - 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 the compressor via the belt pulley or the drive unit to speed up refrigerant oil drainage.
4 - Compressor belt pulley/drive unit
• Replace the belt pulley.
• Check and replace the compressor drive unit. Refer to => [ Compressor Drive Unit ] Compressor Drive Unit
5 - Pressure relief valve, 10 Nm
• Do not remove
6 - Connection with valve
7 - High Pressure Sensor (G65 )
• Removing and installing, refer to => [ High Pressure Sensor ] Service and Repair
• Checking signal, refer to => [ Test Step 5 ] Climatronic Control Module A/C Control Head Electrical Test
8 - Condenser
• Replace the O-ring seals to the connections.
• Refrigerant lines, disconnecting and reconnecting, refer to => [ Refrigerant Lines, Disconnecting and Connecting from Condenser ]
• Condenser, removing and installing, refer to => [ Condenser ] Condenser
9 - Cap
• With seal
• Always screw on
10 - Service connection
• High pressure side
• For measuring, discharging and recharging by service station.
11 - Bolts in refrigerant line
• Replace the O-ring seal.
• Tightening specification: 15 Nm
12 - Restrictor
• Installed in the threaded connection - 11 -
• O-ring seal (7.5 mm/1.5 mm).
• Replace the restrictor with the O-ring seal.
• Removing and installing, refer to => [ Restrictor ] Restrictor
• Coat the O-ring seal lightly with refrigerant oil before installing the restrictor
13 - Evaporator
• Replace the O-ring seals to the connections.
• Tightening specification: Hex nut: 25 Nm
• Removing and installing refrigerant line. Refer to => [ Refrigerant Lines, Disconnecting and Connecting from Evaporator Connection ]
• Removing and installing, refer to => [ A/C Unit ] Overhaul
14 - Service connection
• Low pressure side
15 - Cap
• With seal
• Always screw on
16 - Reservoir
• Replace the O-ring seals to the connections.
• Tightening specification: Socket hex bolt at block connection 10 Nm in screws with an M6 thread and 25 Nm in screws with an M8 thread
• Removing and installing, refer to => [ Reservoir ] Service and Repair