Bleeding the Coolant Circuit

Bleeding the Coolant Circuit

Special tools, testers and auxiliary items required

• Cooling System Charge Unit (VAS 6096)

• The removal of A/C system components is described in this repair manual in such a way that only a small amount of air enters the coolant circuit. Therefore, it is not necessary to bleed the coolant circuit completely after removing and installing these components.

• However, if a large quantity of coolant has escaped due to another problem, for example, due to a leaking hose, the coolant circuit must be completely bled with the (VAS 6096).

• After bleeding and charging the coolant circuit using the (VAS 6096) , the section of the coolant circuit of the A/C system (heater core and associated hoses) is to be post-bled again via the bleeder hole - arrow -.






Bleeding Sections of the A/C System Cooling Circuit

• Since only a small amount of air entered the coolant circuit during installation, for example, of the heater core in the A/C system, the Coolant recirculation pump (V50) , the Coolant shut-off valve (N82) , etc. and the circuit was charged again during installation of the components, only a small amount of air is in the coolant circuit. Therefore, it is sufficient to set the A/C system to maximum heating output when the engine is at operating temperature (so that the Coolant recirculation pump (V50) is actuated) and to run the engine for several minutes at a high idling speed (approximately 2000 RPM) to completely bleed the coolant circuit.

• When bleeding the coolant circuit, take special care to ensure complete bleeding of the heater core. If there are still air bubbles in the heater core, it may cause the customer to complain of insufficient heating performance in winter or different air temperatures from the vents at the same setting in the regulated mode. Refer to => [ Heat Output and Temperature Door Activation, Checking ] Heat Output and Temperature Door Activation, Checking.

Bleeding






- Attach the pipe (V.A.G 1274/10) to the adapter (V.A.G 1274/8).

- Add coolant until the coolant system tester tube is full. When necessary, replenish during the bleeding operation.

- Start the engine and let it run until the operating temperature is reached.

- Set the maximum heating output on the control head, the Climatronic control module (J255) , for the driver and passenger side (such as temperature preselection to "HI").

- Set the fresh air blower speed to approximately 30% of the maximum output.

• The fresh air blower operates at a speed in the lower output range.

- Run the engine at 2000 RPM for 2 minutes.

- Switch off the engine and let it cool down.

- Check the coolant level.






• In the case of a cold engine, the coolant level must be at the MAX mark.

• In the case of a warm engine, the coolant level must be over the MAX mark.