Refrigerant Circuit Repairs
Refrigerant Circuit Repairs
• Refrigerant in refrigerant circuit is never to be topped up (drain, evacuate and refill 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 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.
• The entire amount of refrigerant oil to be added to the refrigerant circuit is in the replacement compressor.
• Zexel / Valeo, Sanden and Denso compressors require different refrigerant oils.
• Beginning the production year 2006, the name of the Zexel A/C compressor was changed from Zexel to Valeo.
• 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 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.
• Check cooling performance.
• Check pressures in refrigerant circuit.
• Refrigerant circuit, servicing, refer to=> [ Refrigerant Circuit Component Overview ] Refrigerant Circuit Component Overview.
HD = High-pressure end
ND = Low-pressure end
1 - A/C Compressor Regulator Valve (N280)
• Do not remove.
• Check 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.
• A/C Compressor Regulator Valve (N280) is activated by Climatronic Control Module (J255) / A/C Control Module (J301) These control modules control the pressure on the low pressure side of the refrigerant circuit.
2 - A/C Compressor
• Remove A/C compressor from and reinstall onto the bracket. Refer to=> [ Compressor, Removing From Bracket ] Compressor, Removing From Bracket.
• A/C compressor refrigerant line, disconnecting and reconnecting, refer to => [ A/C Compressor Refrigerant Lines ] A/C Compressor Refrigerant Lines.
• To protect the A/C compressor, the engine should only be started with the refrigerant circuit completely assembled.
• Remove ribbed belt.
• A/C compressor, removing and installing, refer to => [ A/C Compressor ] A/C Compressor.
• Depending on time period of production and on engine, compressor construction type may vary. Refer to Electronic Parts Catalog (ETKA).
• A/C compressors made by Denso (type 7 SEU 16 or 7 SEU 17) were installed at Start Of Production (SOP). Starting with MY 04 A/C compressors made by other manufacturers (Delphi, Sanden or Zexel / Valeo) were installed.
• Beginning the production year 2006, the name of the Zexel A/C compressor was changed from Zexel to Valeo.
• These A/C compressors are available as replacement parts with different oil fill capacities, therefore note capacity on A/C compressor.
• Depending on A/C compressor type, different refrigerant oil fill capacities are designated for the refrigerant circuit. The reason for the different oil capacities in the A/C compressor for an otherwise identical refrigerant circuit lies in the design of the A/C compressor itself, note these oil capacities. Too much oil in the circuit leads to higher pressures and reduces cooling performance of the system. Too little oil may lead to lubrication problems in the compressor.
• If a new compressor has been installed or new refrigerant oil has been put into the A/C compressor (e.g. after blowing through the A/C system), the A/C compressor must be turned by hand approximately 10 revolutions. This ensures that the compressor is not damaged when activated.
3 - Belt Pulley
• Replacing, refer to=> [ A/C Compressor and Pulley ] Service and Repair.
• Ribbed belt, removing and installing, refer to=> Engine, Mechanical Removal and Installation.
• The Delphi A/C compressor belt pulley cannot be removed separately.
• 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 and 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 and => [ A/C Compressor and Pulley ] Service and Repair.
4 - Oil Drain Plug
• Denso and Delphi A/C compressors have a sealing ring installed, replace
• Sanden A/C compressors have an O-ring (8.8 mm x 1.5 mm) installed, always replace.
• Zexel/Valeo A/C compressors have an O-ring (7.6 mm x 1.9 mm) installed, always replace.
• Beginning the production year 2006, the name of the Zexel A/C compressor was changed from Zexel to Valeo.
• Tightening specifications: Denso A/C compressor 30 Nm, Sanden- A/C compressor and Zexel A/C compressor 10 Nm
• Tightening specifications: Delphi A/C compressor 15 Nm
• Should only be unscrewed to drain refrigerant oil and with the A/C compressor removed. Turn the A/C compressor via belt pulley, to speed up refrigerant oil drainage.
5 - Pressure Relief Valve
• Do not remove.
• Tightening specifications: Sanden A/C compressor 14.5 Nm, Denso- A/C compressor and Zexel / Valeo A/C compressor 10 Nm
• With O-ring Denso A/C compressor, Sanden A/C compressor and Zexel / Valeo A/C compressor: 8.5 mm x 1.75 mm
• Delphi A/C compressor with sealing ring, tightening specification: 15 Nm
6 - Connection With Valve
• Different component locations depending on engine, item 6a shows component location in vehicles with 2.0 L Diesel engine
• 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).
7 - High Pressure Sensor (G65)
• Removing and installing, refer to => [ High Pressure Sensor (G65) ] Service and Repair.
• Checking signal, refer to=> [ High Pressure Sensor (G65), Checking Pressure Signal ] Testing and Inspection.
• Different component locations depending on engine, item 7a shows component location in vehicles with 2.0 L Diesel engine.
8 - Condenser
• Refrigerant lines, disconnecting and reconnecting, refer to=> [ Condenser Refrigerant Lines, Disconnecting and Connecting ] Condenser Refrigerant Lines, Disconnecting and Connecting.
• Condenser, removing and installing, refer to => [ Condenser ] Condenser.
9 - Fluid Reservoir
• Coat O-ring seals lightly with refrigerant oil before installing. Refer to=> [ Refrigerant Circuit O-rings ] Refrigerant Circuit O-Rings.
• Replacing the O-ring seals. Refer to Electronic Parts Catalog (ETKA).
• Removing and installing, refer to => [ Fluid Reservoir ] Fluid Reservoir.
• Different versions (secured by one or two bolts, with or without seals against moisture in connection area). 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 => [ Dryer Cartridge, Denso Condenser ] Dryer Cartridge, Denso Condenser or => [ Dryer Cartridge, Modine Condenser ] Dryer Cartridge, Modine Condenser.
• Dryer cartridge (on a condenser with an integrated fluid reservoir), removing and installing, refer to => [ Dryer Cartridge, Denso Condenser ] Dryer Cartridge, Denso Condenser or => [ Dryer Cartridge, Modine Condenser ] Dryer Cartridge, Modine Condenser.
10 - Service Connection
• High pressure side.
• For the A/C service station for measuring, discharging and recharging using service station, refer to => Refrigerant
R134a Servicing Description and Operation (A/C Service Station).
• Depending on engine version, it may be necessary to remove some components (for example, EVAP canister) in order to be able to connect to service coupling.
• 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).
Only remove service connections when the refrigerant circuit is empty. The connection does not have a valve.
11 - Sealing Cap
• With a seal.
• Always screw on.
12 - Expansion Valve
• Refrigerant lines, disconnecting and reconnecting, refer to=> [ Expansion Valve Refrigerant Lines, Disconnecting and Connecting ] Expansion Valve Refrigerant Lines, Disconnecting and Connecting.
• 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.
13 - Evaporator
• A/C unit with evaporator, removing and installing, refer to=> [ A/C Unit ] A/C Unit.
• Removing and installing evaporator from heating & A/C unit, refer to=> [ Evaporator ] Evaporator.
14 - Service Connection
• Low pressure side.
• For the A/C service station for measuring and discharging using service station, refer to => Refrigerant R134a
Servicing Description and Operation (A/C Service Station).
• Depending on engine version, it may be necessary to remove some components (for example, EVAP canister) in order to be able to connect to service coupling.
• 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).
Only remove service connections when the refrigerant circuit is empty. The connection does not have a valve.
15 - Sealing Cap
• With a seal.
• Always screw on.
16 - Pre-volume
• Is a component of refrigerant line from expansion valve to A/C compressor.
• Pressure fluctuations are damped in the damping chamber.
• Not installed in all vehicles (at this time, for example, not installed in vehicles with 2.0 L Diesel engine). Refer to Electronic Parts Catalog (ETKA).
17 - Connection In Refrigerant Line
• Replacing the O-ring seal. Refer to Electronic Parts Catalog (ETKA).
• Not installed in all vehicles (for example, installed in 6 cylinder vehicles).
• Disconnecting and connecting connection, refer to=> [ Connecting Points In Refrigerant Line, Disconnecting and Connecting ] Connecting Points In Refrigerant Line, Disconnecting and Connecting.