Refrigerant Circuit, Evacuating

Special tools and workshop equipment required 

• A/C Service Station

• Depending on the A/C Service Station used, changes to the work procedure may be needed. Pay attention to the Owner's Manual. Refer to Owner's Manual.
• The refrigerant circuit is evacuated via the high and low pressure connections.
• The refrigerant circuit is completely assembled.

Procedure 

Vehicles with High-Voltage System

-- Deactivate the "parking air conditioner". Refer to Owner's Manual.

Vehicles with high-voltage system, for which electric activated valves in the refrigerant circuit are not open when de-energized.

-- Open the electric activated valves for the refrigerant circuit for extracting, evacuating and filling. Refer to Refrigerant Circuit and the Vehicle Diagnostic Tester .

Tip

For vehicles with high-voltage system and secondary functions of the A/C system, valves may be installed in the refrigerant circuit. To guarantee correct draining, evacuating and filling of the refrigerant circuit, no segments are allowed to be closed off. That is why the valves need to be opened before respective work procedures. Refer to Refrigerant Circuit .

Continuation for all vehicles

-- Switch off the ignition.

-- Start the A/C Service Station according to its operating instructions. Refer to the A/C Service Station Operating Instructions.

-- Connect the A/C Service Station to the refrigerant circuit. Refer to A/C SERVICE STATION ON REFRIGERANT CIRCUIT, CONNECTING .

-- Evacuate the refrigerant circuit and perform a vacuum test. Monitor the following reference values at the A/C Service Station.

The refrigerant circuit was not opened and there are no signs of leaks.

• Vacuum time: 10 minutes
• Vacuum/pressure increase test: 5 minutes

Tip

Depending on the A/C Service Station it may be the case that the time references must not fall short of a specified duration.

The refrigerant circuit was open

• Vacuum time: minimum 30 minutes
• Vacuum/pressure increase test: 5 minutes

Continuation for all vehicles

• At the end of the evacuation procedure the pressure must be below 5 mbar absolute pressure.
• At the end of the vacuum/pressure increase test, the refrigerant circuit pressure must not be higher than 20 mbar absolute pressure.

Possible causes of malfunction for not reaching the vacuum during the evacuation process:

• Time for the evacuation process was set too short
• Leak in the refrigerant circuit. Refer to LEAKS, FINDING .
• Leaks in between the vehicle and the A/C Service Station.
• The vacuum pump of the A/C Service Station does not create the required vacuum
• The vacuum sensor of the A/C Service Station is not calibrated correctly. Refer to Owner's Manual A/C Service Station.

Possible causes of malfunction for not reaching the vacuum during the vacuum/pressure increase test:

• Leak in the refrigerant circuit. Refer to LEAKS, FINDING .
• Time for the evacuation process too short and the time for the vacuum/pressure increase test is set too long
• Leaks in between the vehicle and the A/C Service Station.
• Leaks within the A/C Service Station

Tip

• Even if the refrigerant circuit is sealed, evaporating refrigerant from the refrigerant oil or humidity as well as other factors (for example the amount of refrigerant oil in the refrigerant circuit, age and mileage of the vehicle, design of the refrigerant circuit) can lead to the specified absolute pressure rising above 20 mbar during the vacuum test. If this is the case, repeat the procedure again if necessary and/or adjust the pre-set times accordingly.

If the vacuum reading does not change (and the pressure remains smaller than 20 mbar) the system does not have leaks and can be filled.