A/C System, Operating after Filling Refrigerant Circuit

A/C System, Operating after Filling Refrigerant Circuit


• All removed parts are installed.

• The refrigerant circuit is filled.

- Switch on the ignition.

- Check the Climatronic control module (J255) display and control head DTC memory and erase any displayed malfunctions if necessary. Refer to Vehicle Diagnostic Tester under "Guided Fault Finding".

- Operate the electric A/C compressor (V470) using the function "Compressor Cut-In". Refer to Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for the A/C System and Battery Control.

• Note the information regarding operating the A/C system after filling.

Without a high voltage system

• Only start engine after refrigerant circuit has been assembled.

• If possible, start engine only with a filled refrigerant circuit.

• Do not start the engine while evacuating the refrigerant circuit or when the circuit is already evacuated (the A/C compressor could be damaged).

• The A/C compressor without an A/C clutch (N25) is always driven when the engine is running. If the vehicle has an A/C compressor without an A/C clutch, then the vehicle may only be started when the 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 operating with a fixed resistance (sealed circuit).

• An A/C compressor with an A/C clutch is installed as a running change on certain 4-cylinder vehicles from MY 12. Refer to => [ Belt Pulley with A/C Clutch (N25) Overview ] Belt Pulley With A/C Clutch (N25) Overview. The A/C clutch turns off the A/C compressor drive completely under certain conditions (for example "ECON"). The correct Climatronic control module (J255) must be installed and it must be coded correctly so that the Climatronic control module display and control unit can control the A/C clutch. Refer to the Electronic Parts Catalog (ETKA) and to the Vehicle Diagnostic Tester under "Guided Fault Finding".

• The A/C compressor without an A/C clutch is always driven by the belt pulley or driveshaft. To prevent damage when the compressor is idling, it is lubricated by an "internal oil circuit".

• The compressor has an "internal oil circuit" to ensure the A/C compressor is not damaged when refrigerant circuit is empty. Prerequisite for the internal lubrication is residual refrigerant oil in A/C compressor.

• A/C Compressor Regulator Valve (N280) is not activated when the refrigerant circuit is empty and the A/C compressor idles with the engine. As there is no refrigerant in the circuit the oil required to lubricate is not fed to the A/C compressor.

• All removed parts are installed.

• The refrigerant circuit is filled.

If it is necessary to start the engine with a discharged refrigerant circuit:

• Refrigerant circuit must be fully assembled.

• There must be no vacuum in the refrigerant circuit.

• At least 1/4 of the prescribed refrigerant oil must be in the A/C compressor.

• Do not rev engine higher than 2500 rpm.

• The engine should only run as long as is absolutely necessary.

Note the following when starting engine for first time after filling refrigerant circuit:

- Switch on the ignition.

- Check the Climatronic control module (J255) display and control head DTC memory and erase any displayed malfunctions if necessary. Refer to Vehicle Diagnostic Tester under "Guided Fault Finding".

- Start engine with the A/C compressor switched off ("Econ" operating mode set, indicator light in AC button does not light up), and wait until engine idle speed has stabilized.

- Open all instrument panel vents.

- Set the temperature preset on the A/C Control Head Climatronic Control Module (J255) to "cold" (for the driver and passenger side).

- Press the AC button to switch on the A/C compressor ("Auto" mode selected and the indicator light in the AC button is on) and let the engine and A/C compressor idle for at least 5 minutes.

• Note the information regarding operating the A/C system after filling.