Audi A6 2.8L car, which runs about 53 thousand KM. The owner reflected that the vehicle's windscreen would produce heavy fog and the central outlet would be much smaller than the wind on both sides. Fault diagnosis: (1) first of all, the problem of the wind reflected by the owner is verified. (2) check the refrigerant pressure of the air conditioning system and result in normal pressure. (3) VAS5051 into 08 to find fault memory, fault code: 00355003 left front chest outlet position control motor V237 mechanical fault, 00356003 right front chest outlet position control motor V238 mechanical fault 00712003 right foot space valve control motor V109 mechanical failure after mechanical fault 00715003 foot space vent control motor Vl12 foot control motor Vl12 Mechanical fault 00716003 air recirculation valve control motor Vl13 mechanical fault 00797009 daylight transmission light sensor G107 circuit breaker / ground short circuit 00797009 daylight transmission light sensor G107 circuit breaker / ground short circuit 00797009 daylight transmission light sensor G107 circuit breaker / ground short circuit 01274003 airflow plate position motor V71 mechanical fault 020250 02 the lower limit of the power supply voltage of the external components can not reach (4) the fault of the control unit can be displayed by the guidance fault inquiry or the 5V voltage supply of each throttle motor is checked. Find the circuit diagram that the 5V voltage is sent by the control unit, the actual measurement voltage is less than 1V. (5) the air conditioning control unit is replaced according to the phenomenon, and the voltage is still less than 1V. (6) when the control unit is good, then it is doubtful whether the 5V voltage loss is caused by an internal short circuit of a damper motor. Therefore, each air door motor is tested with one plug and the voltage is measured at the same time. In the process of Pluping the plug, the fault lookup of VAS5051 suddenly comes out with a fault code: the sunlight sensor is short circuited by the sensor. The circuit diagram shows that the sensor is connected by two separate lines of the control unit. Will the control unit fail to output the 5V voltage due to the short circuit of the component? (7) then the component is replaced, the electric motor voltage of the valve is measured to 5V, then the basic setting of the valve motor is set, the fault memory is cleared, the fault is eliminated, and the sunlight irradiation sensor is replaced. Failure summary: at the beginning, there was no sun sensor fault, but when the door was inserted.