Refrigerant Circuit, Servicing
Refrigerant Circuit, Servicing
• 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 from 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.
• Refer to => [ A/C Unit, Checking Cooling Output ] A/C Unit, Checking Cooling Output.
• No refrigerant must be added into the refrigerant circuit (discharge, evacuate and recharge refrigerant circuit).
• 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 seals lightly with refrigerant oil prior to installation. 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-ring seals that have been approved for use with refrigerant R134a. Refer to => [ Refrigerant Circuit O-rings ] Refrigerant Circuit O-Rings and Electronic Parts Catalog.
• Check pressures in refrigerant circuit.
• Operate the A/C system after filling the refrigerant circuit. Refer 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)
• Check the activation signal. Refer to => [ A/C Compressor Regulator Valve (N280), Checking Switch-On Signal ] A/C Compressor Regulator Valve (N280), Checking Switch-On Signal.
2 A/C Compressor
• Different versions. Refer to Electronic Parts Catalog.
• Overview, refer to => [ Refrigerant Lines, Condenser, Expansion Valve, A/C Compressor Overview ] Refrigerant Lines, Condenser, Expansion Valve, A/C Compressor Overview.
3 Pressure Relief Valve
• Do not remove
• O-ring seal - replace
• Denso A/C compressor - dimensions 8.5 mm x 1.75 mm
• Tightening Specifications
• Denso A/C compressor - 10 Nm
4 Oil Drain Plug
• 30 Nm
• Different version. Refer to Electronic Parts Catalog.
• Replace the O-ring seal
• May only be removed to drain the refrigerant oil with the A/C compressor removed, rotate the A/C compressor via the belt pulley to accelerate the draining of the refrigerant oil.
5 Sealing Cap
• With seal
• Always to be screwed on
6 Low Pressure Side Service Connection
• In the area of the left suspension strut tower.
• For measuring and emptying.
The service connections may only be removed with the refrigerant circuit discharged.
• The service connection is installed at the refrigerant line to the inner heat exchanger.
7 Refrigerant Line - Low Pressure Side
8 Evaporator
• Removing and installing, refer to => [ Evaporator, A/C Unit Installed ] Service and Repair.
9 Expansion Valve
• Disconnect and connect the refrigerant line with the inner heat exchanger, refer to => [ Refrigerant Tube with Inner Heater Exchanger ] Refrigerant Tube With Inner Heater Exchanger.
• 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.
10 Refrigerant Tube With Inner Heat Exchanger
• In this refrigerant line, the liquid warm refrigerant flowing on the high pressure side releases heat energy into the vaporous cold refrigerant flowing on the low pressure side. This increases the cooling efficiency of the A/C system.
11 Refrigerant Line - High Pressure Side
12 High Pressure Side Service Connection
• In the area of the left suspension strut tower
• For measuring, emptying and filling.
The service connections may only be removed with the refrigerant circuit discharged. The connection does not include a valve.
• The service connection is installed at the refrigerant line to the inner heat exchanger.
13 Sealing Cap
• With seal
• Always to be screwed on.
14 Fluid Reservoir With Desiccant Bag
• Different versions. Refer to Electronic Parts Catalog (ETKA).
• Overview, refer to => [ Refrigerant Lines, Condenser, Expansion Valve, A/C Compressor Overview ] Refrigerant Lines, Condenser, Expansion Valve, A/C Compressor Overview.
15 A/C Pressure/Temperature Sensor (G395)
• Check the pressure signal. Refer to => [ A/C Pressure/Temperature Sensor (G395), Checking Pressure Signal ] A/C Pressure/Temperature Sensor (G395), Checking Pressure Signal.
• Removing and installing, refer to => [ A/C Pressure/Temperature Sensor (G395) ] A/C Pressure/Temperature Sensor (G395).
16 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.
Only remove the valve insert when the refrigerant circuit is empty.
17 Condenser (With Fluid Reservoir)
• Different versions. Refer to Electronic Parts Catalog (ETKA).
• Overview, refer to => [ Refrigerant Lines, Condenser, Expansion Valve, A/C Compressor Overview ] Refrigerant Lines, Condenser, Expansion Valve, A/C Compressor Overview.
18 Belt Pulley/Drive Unit
• Different versions. Refer to Electronic Parts Catalog (ETKA).
• Replace the belt pulley. Refer to => [ A/C Compressor Belt Pulley ] Description and Operation.