Symptom: the owner reflects the recent hot weather. In the driving time are open air conditioning. The cooling effect has been very good, and this time the dashboard suddenly there is no wind blowing out of the wind.
    Troubleshooting: Run the engine. Check the buttons on the control panel in the center of the dashboard. The button display function are normal, but the dashboard of the outlet without a trace of wind blowing. And did not feel any signs of the operation of the inside of the dashboard. Taking into account the Mercedes-Benz car air-conditioning system is more complex, decided to do the control module self-diagnosis. Connect the STAR original diagnostic instrument and select the S-level W220165 chassis configuration. In the control module section select "AAC-Automaticaircondition", click "Faultcodes" function item query fault information. Display: B1268cotmmunicationfault0fACBUSwithcotltroIunitN18 / 4 (centerventelectronicscontrolrnodule) meaning "with the control module N18 / 4 (central ventilation control module) air conditioning BUS network communication failure." The fault code is cleared and the fault code is successfully cleared. But the dashboard of the outlet is still no wind blowing. We know that the Mercedes-Benz W140 chassis air conditioning system if there is no wind blowing, or air volume can not be adjusted, the usual failure is the blower electronic amplifier damage. The W220 chassis air conditioning system has undergone great changes. Some components of the installation site is not very clear. In order to get more diagnostic help. We call the wls maintenance repository. Select the 83.40 area wiringdiagramofautormaticairCOtlditiorlAACcorntrolmodule. Open the automatic air conditioning control module N22 circuit diagram. In the circuit. We clearly see the control module N22, blower motor A32ml and blower electronic regulator A32nl between the three lines of connection: A32nl controlled by N22, and A32rnI operating current adjustment, in order to change the blower speed.
    Continue to analyze the circuit diagram and find that the operating power of the blower is not provided by the control module N22, but by the external fuse relay module K40 / 7. And the air conditioning system related to the fuse for the 23,47,35,82,33, one by one investigation. Are good. According to the WIS component location map, we determined that the blower is located at the bottom right of the dashboard. Unpack the blower housing and check that the 3-pin plug of the blower motor melts due to overheating. And saw the plug had been repaired. But the line is not firmly connected, is caused by the direct cause of overheating. Re-do welding processing. Install test run. The blower is running back. Compressor pull, dashboard air outlet air conditioning, air conditioning failure to this rule.
    Fault Summary: W220 chassis automatic air conditioning system control principle is more complex. It is through several control modules between the CAN bus data transmission and sharing to achieve. So we must first of several important control module to know:
  Air conditioning button control module N22: air conditioning system is the main control module, combined with the air conditioning control panel, by pressing the button. To adjust and control the air conditioning status. At the same time, the module N22 also processes the received various types of sensor signals. In order to manipulate the actuators
    Rear air conditioning button control module N22 / 4: mainly for the rear air conditioning state control
    Stepper motor control module N22 / 5: Control for actuators of the solenoid valve for each outlet of the dashboard and the heater
    Central panel control module: N18 / 4
    Left front body SAM control module N10 / 6
    Right front body SAM control module N10 / 7
    As for how to achieve automatic control of air conditioning, or how many control modules are organically combined to achieve the various functions of air conditioning systems. Data provided in the three functions of the work flow chart, we can make the entire air conditioning system control principles have a more specific understanding.
    (1) Control of the air conditioning compressor: The signal is transmitted by N22 via CAN bus to N10 / 6.N10 / 6 is transferred to N10 / 7 via data cable (right front fuse relay module K40 / 7 and N10 / 7 is a assembly) N10 / 7 triggers K40 / 7 to drive the compressor.
    (2) the control of the radiator fan: the signal input port has two, one coolant temperature sensor B11 / 4 signal to the engine control module N3, CAN bus to the instrument panel unit A1, and then CAN bus to N22: Second, the external temperature sensor B14, and the refrigerant temperature sensor B12 and air conditioning pressure sensor B12 / 1 signal to N10 / 6, CAN bus to N22. N22 after the two groups of signal analysis. The trigger signal is transmitted via CAN bus to N10 / 7 and K40 / 7, and then transmitted from the data cable to fan control module N76 to drive the fan.
    (3) Internal loop control: If you press the cycle button of the air conditioning control panel, the system may provide the function of closing the window and the skylight. The control flow: The signal is controlled by N22 through CAN bus to 4 door gating module N69 / 1, N69 / 2, N69 / 3 and N69 / 4, and then drive the window lifter motors M10 / 3, M10 / 4, M10 / 5 and M10 / 6. Similarly, the signal is controlled by N22 via CAN bus to skylight control module N70 to drive the sunroof motor M12 / 1.
    Thus, a function of the realization, from the signal acquisition to the implementation of the trigger. To pass through a number of control module information transmission, the communication line may be CAN bus. Or a single data cable until the terminal performs the element. This is also the control characteristics of the automotive network system, maintenance personnel testing ideas must adapt to the trend of this change in order to make a correct judgment on the fault.