General Information

General Information

Special tools, testers and auxiliary items required

• Vehicle diagnosis, testing and information system (VAS5051B) (or Vehicle Diagnosis and Service System (VAS 5052) ).

• If coolant circuit is not completely bled after filling, air may accumulate in heater core of A/C unit, thus reducing heating performance of A/C system, additional noises may occur or customer may complain of different air temperatures flowing out of vents at driver side and front passenger side at the same setting. For this malfunction, perform a long road test at increased engine speed (at least 10 minutes, engine speed greater than 2500 RPM). Select a low gear during the test to prevent excessive vehicle speed.

• If customer complains of poor heating performance at specific engine speeds, check incorporation of heater core in A/C system in the coolant circuit. If both coolant hoses (supply and return) of engine are interchanged, coolant is flowing in the wrong direction through the heater core.

• In vehicles with a parking heater, check activation of Recirculation Pump (V55) , of parking heater as well as incorporation of parking heater in coolant circuit.

• If a Climatronic control module (J255) , part number 8P0 820 043 from index BM is installed, then the request to activate the electric coolant pump is sent only if adapted correctly to the Data bus. See if the Climatronic control module part number has the index BM is installed. Check using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding".

• Check the heating output, on vehicles with automatic climate control system, refer to => [ Heating Performance - With Automatically Regulated A/C System ] Heating Performance - With Automatically Regulated A/C System.

• Check the heating output, vehicles with manual climate control system, refer to => [ Heating Performance - With Manually Regulated A/C System ] Heating Performance - With Manually Regulated A/C System.