【Fault description】
    Owners reflect the vehicle after running, the dashboard air conditioning control panel temperature set to a minimum, the outlet still feel cool enough.
    【Inspection process】
    In the air conditioning pipe connected to the air conditioning pressure gauge, start running the engine, the automatic air conditioning temperature set at 18 ℃, observe the pressure gauge changes. Low pressure piping pressure down to 225kPa, high pressure pipe pressure rose to 1200kPa, indicating the compressor pull work. Touch the temperature of the air conditioning low-pressure line by hand, feel warm, and the temperature of the high-pressure line between the condenser and the evaporator, feel hot, but also see the electronic fan in front of the condenser is not running. Obviously, this high and low pressure pipeline temperature is too high the main reason is due to poor system cooling caused. As the high-pressure pipeline refrigerant pressure is low, in the first easy after the difficult test principle, first added 150g refrigerant, the results of high-pressure pipeline refrigerant pressure rose to 2000kPa or more, the pressure rise too fast is very dangerous So close the air conditioning, the maintenance ideas will focus on the electronic fan control lines.
    Connect the GT1 original diagnostic instrument, select the X system E53 chassis, enter the self-diagnosis main menu, double-click "IHKA automatic air conditioning heating and cooling system", enter the electronic control module, query fault storage, GT1 shows a windshield heating on the failure Information, which is not directly related to the failure of this case, clear the fault information, select "DME digital electronic engine servo system M72" electronic control module, query fault memory, GT1 display:
    (125) 7D tank outlet temperature sensor
    (098) 62 Fuel tank ventilation solenoid valve control
    (140) 8C according to the characteristic curve cooling control
    (141) 8D electronic fan control