A/C System, Operating After Charging
If the mechanically driven A/C compressor has been removed, rotate it about 10 times by hand prior to initial start-up (when or after installing, for example prior to installing the ribbed belt) to prevent damage caused by liquid impact when first switched on (any refrigerant oil in compressor cylinder is forced out on rotation). Refer to A/C COMPRESSOR, REMOVING AND INSTALLING .
If the electronically driven A/C compressor was removed, activate it after filling the A/C compressor before the A/C system on via the "basic setting, compressor cut-in" function for the Guided Fault Finding. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function for A/C System and battery regulation. This prevents the A/C compressor from becoming damaged for example by liquid impact when it is first switched on (any refrigerant oil in the A/C compression chamber is forced out).
The vehicle engine drives the mechanically driven A/C compressor via a belt or shaft. The electrically-driven A/C compressor is driven via an electric motor directly on the A/C compressor. Refer to A/C COMPRESSOR, REMOVING AND INSTALLING .
Operating an A/C System with a Mechanically Driven A/C Compressor
-- Switch the ignition on.
-- Adjust the A/C system to the lowest possible output (for example select "A/C off" mode).
-- Switch off the A/C compressor activation (for example select "A/C off" mode).
-- Start the engine with the A/C compressor switched off (for example select "A/C off" mode).
-- Wait until idle speed has stabilized.
-- Switch on the A/C compressor and operate the system for at least two minutes at idle speed.
-- If necessary, check pressures in the refrigerant circuit using the A/C service station. Refer to WORKING WITH A/C SERVICE STATION .
-- Turn the engine off.
-- Disconnect and the A/C service station from the refrigerant circuit and turn it off. Refer to A/C SERVICE STATION, SWITCHING OFF AND DISCONNECTING FROM REFRIGERANT CIRCUIT .
Operating an A/C System with an Electrically Driven A/C Compressor
-- Switch the ignition on.
-- Operate the A/C compressor using "basic setting, compressor cut-in" in Guided Fault Finding. Refer to Vehicle Diagnostic Tester,"Guided Fault Finding" function in A/C system and battery regulation.
Additionally on vehicles with electric operated valves in the refrigerant circuit, which cannot be opened without power:
-- Via the Vehicle Diagnostic Tester the electrically activated valves which do not open without power for the operation of the A/C system enable the activation of these valves via the respective control module (to open or close) using the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
On vehicles with high-voltage system and additional functions of the A/C system ("heat pump operation" or "cooling the high-voltage battery") valves may be installed in the refrigerant circuit which cannot be opened without power. These valves are opened and closed for example via a step motor and after switching off the ignition are no longer activated. To completely drain, correctly discharge and charge the refrigerant circuit no areas may be closed, for this reason the valves must be opened before these procedures. After finishing work on the activation of these valves are enabled via the respective control module. Refer to Refrigerant Circuit and the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
All A/C systems with electrically-driven A/C compressor
-- After the basic setting and if necessary, check pressures in refrigerant circuit using A/C service station.
-- On vehicles with a high-voltage system, switch off (deactivate) the "auxiliary climate control" function. Refer to the Owner's Manual and Infotainment/MMI Operating Manual.
-- Switch off the ignition.
-- Disconnect and the A/C service station from the refrigerant circuit and turn it off. Refer to A/C SERVICE STATION, SWITCHING OFF AND DISCONNECTING FROM REFRIGERANT CIRCUIT .
Vehicles with an Electrically-Driven A/C Compressor
- The engine may only be started if the refrigerant circuit is completely assembled.
- Hybrid drive on vehicles with battery cooling is only possible with a fully charged A/C system in which there are no stored errors. Refer to Vehicle Diagnostic Tester in the"Guided Fault Finding" function for the a/c system and the battery regulation.
- After the installation of the electrically-driven A/C compressor and the subsequent filling of the refrigerant circuit, start the A/C compressor for the first time using the "compressor intake" function for the basic setting. The A/C compressor may otherwise become damaged if refrigerant oil was improperly stored in the A/C compressor compression chamber before installation. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" Function for A/C System and Battery Regulator.
- Only activate the electrically-driven A/C compressor when the refrigerant circuit is filled. The A/C compressor may become damaged if the A/C compressor is run while the refrigerant circuit is empty. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function for A/C system and battery regulation.
-- Charge the vehicle battery, for example, using the Battery Charger :VAS5904 in the battery support mode to minimize the number of automatic starts during the test- and measuring procedures while the ready mode is active. Refer to Battery, Charging and the appropriate service information .
-- For testing and measurement procedures that require the ready mode to be active or the ignition to be switched on, the selector lever must be in the "P" position and the parking brake must be activated. The required tools must be placed so that they do not come into contact with any rotating components in the engine and they must also not go into the vicinity of the rotating components when the engine is running.