A8L V8-4.2L (BFM) (2004)
Heater Control Valve: Testing and Inspection
Pump Valve Unit, Checking Function
Pump Valve Unit, Checking Function
In this test, function of pump valve unit (Left Heat Regulating Valve (N175), Right Heat Regulating Valve (N176) and Coolant Pump (V50)) is
checked.
‹› If the determined temperatures lie below the specification (heating performance too low):
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Check the function of the Left Heat Regulating Valve (N175), Right Heat Regulating Valve (N176) and Coolant Pump (V50) vehicle diagnosis
testing and information system VAS 5051 in the "Guided Fault Finding" function.
If no malfunctions are detected:
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Check for interchanged coolant hoses from engine to pump valve unit or from pump valve unit to heater cores of air conditioner. Refer to=> [
Pump Valve Unit, Checking ] See: Pump Valve Unit, Checking
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Check for interchanged electrical terminals of Coolant Pump (V50) of pump valve unit (direction of pump operation).
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On vehicles with a parking/an auxiliary heater, check the activation of the parking heater Recirculation Pump (V55) and the parking/auxiliary
heater connection in the coolant circuit and vehicle diagnosis, testing and information system VAS 5051 in the "Guided Fault Finding" function.