Failure phenomenon: a 2007 annual output of Toyota Reiz 2.5L sedan (GRX12 series), the user reflects the air conditioning is not normal, air conditioning continued to work about 10min, the outlet began to blow hot air. At this point if the air conditioning and then open again, air conditioning and began to cool.
    Check the analysis: maintenance personnel after receiving the car, first connected to the Toyota IT Ⅱ fault diagnosis machine to read the air conditioning system fault code, there are three fault code storage, of which two are on the left and right sun sensor fault code, the other is the air mixing control Servo motor circuit (passenger side) fault code B1441. For the first two fault codes, should be caused by lack of outside light, when the vehicle to the outside of the workshop, the fault diagnosis device shows the current fault code only B1441. It can be seen from the air conditioning system data stream that the pulse value of the air mixing damper control servo motor (passenger side) is always 105 and does not change, and the values ​​of the other damper motors are subject to change in wind direction and temperature regulation, indicating that the passenger There is a problem with the side servo motor.
    In order to determine whether it is a line problem or a motor problem, use the active test function of the fault diagnosis instrument to select the control of the air mixing fan control servo motor circuit (passenger side) from the menu and then manually control the motor operation. At this point the motor pulse value has changed, and can clearly hear the motor issued a "click" sound. When the active test is withdrawn, the motor will sound the same sound, and no other sounds will be issued for other damper motors. Therefore, the maintenance personnel to determine the damper card or motor internal sliding teeth, but this failure should be no direct relationship with the air conditioning is not cooling.
    Check the air conditioner A / C switch, when the A / C switch off, the compressor electromagnetic clutch disconnected, when the A / C switch is closed, the electromagnetic clutch can pull. In the vehicle at rest, the air conditioning work time more than 20min air conditioning is still working properly. And the road test, only driving 3km, feeling the temperature inside the car began to rise, feel the outlet is the natural wind blowing, but the parking check found that air conditioning compressor electromagnetic clutch always sucked. Observe the value of the evaporator temperature sensor displayed on the fault diagnosis device is gradually increased, then the compressor control current value of 0.80A, the compressor pressure sensor value is only 0.80MPa or so. It can be seen from the curve of the air conditioning working condition of the vehicle that the evaporator temperature corresponding to point 1 is 2.4 ℃, the compressor pressure sensor value at point 2 is 1.19MPa, and the compressor control current at point 3 is 0.35A. From this time on, the temperature of the evaporator rises gradually until the highest point of the curve on the right side of the screen is 20.8 ° C. In this process (point 5), the compressor control current is always 0.80A, while the compressor pressure sensor value is always low, from 1.19MPa down to 0.80MPa or so. From this process, the air conditioning control unit has reduced the control current to the compressor (down to 0.35A) when the evaporator temperature is low, thus avoiding evaporator freezing. However, after the evaporator temperature began to rise, the compressor control current from the observation point 3 to point 5, has returned to the normal current value of 0.80A, but the compressor pressure has never been increased.
    Connected to the air conditioning pressure manifold table, before the start of road test, air conditioning system normal high and low pressure were 1.50MPa and 0.20Mpa. When driving about 3km, and found that air conditioning is not cooling, and then check the pressure gauge, high and low pressure were 1.15MPa and 0.54MPa, which is not normal. Because before the compressor has been determined to control the current state in the normal state, and then break off the A / C switch after a moment, and then press the A / C switch air conditioning system can work to analyze, the cause of the failure should be inside the compressor can be Variable chamber due to problems. The maintenance personnel believe that when the compressor is working for a period of time, when the working volume changes, the internal leakage (or because the electromagnetic control valve seal is not strict leakage), then turn off the switch, and then open the A / C switch, Electromagnetic control valve can be restored after the normal power, the pressure can be established, air conditioning can be cooled again.
    Troubleshooting: replace the new air conditioning compressor, and according to the standard refrigerant charge, the air conditioning can work properly, the test failure did not appear.