Symptom: a Toyota sea lion (HIACE) small passenger air conditioning air temperature control failure.
    Failure analysis: Toyota sea lion (HIACE) passenger car equipped with front and rear air conditioning device. After the air conditioning temperature control failure, according to the device structure analysis, the main should check the temperature control switch, thermistor, air conditioning amplifier and its line. Because the temperature is set by the temperature control switch, the thermistor will sense the temperature signal provided to the air conditioning amplifier, and then through the air conditioning amplifier to control the compressor after the cooling operation.
    Maintenance process: available resistance measurement method to determine the temperature control switch is good or bad. Place the switch lever in the cool air (COOL) position and measure the resistance between the two terminals of the temperature control switch (resistor) with a multimeter. Measured the resistance of 1.7kΩ that is not bad. And then check the thermistor wire connector, remove the thermistor, immersed in a cup filled with cold water and ice; insert the thermometer, and then change the temperature of the water, while using a multimeter to measure the resistance of the two ends of the connector Of the resistance, combined with the thermometer indicates the water temperature, the control of the two curves, the results found that the resistance value does not match. This indicates that the thermistor is damaged.
    Replace the new thermistor test, the resistance value changes normal. Charge, test machine, air conditioning air temperature control back to normal.