Symptom: air conditioning failure. When the engine starts up temporarily idling run, only hear 'whiz,' the sound, automatic air conditioning on the failure.
    Troubleshooting: a look at the engine room, sampler safety valve (fusible fuse) spray out of the refrigerant medium, at a glance can be confirmed.
    The role of the safety valve is that when the pressure on the high pressure side is abnormally high, the refrigerant temperature rises and the special fusible solder inside the safety valve melts to discharge the refrigerant medium to prevent damage to the compressor and other parts. In general, it can be concluded that the cold suspects are clogged and the cooling is insufficient, or the condenser fan malfunctions. For the car, the actual investigation of the condenser, the condenser is not blocked, the internal is not dirty, no problem.
    Second, the investigation of electric fans, the refrigerant medium has been light leakage, the pressure switch can not move, so with a jumper short pressure switch to investigate the fan motor action. Close the ignition switch, radiator fan and condenser fan operation are normal, the results are no problem.
    So start the engine again, to investigate the electromagnetic clutch action does not move, air conditioning compressor rotation does not rotate, the results although the refrigerant medium light leakage, pressure switch off, air conditioning compressor operation is still normal. Pressure switch off, air conditioning compressor normal operation, certainly the pressure switch or AC (automatic air conditioning) with a computer short circuit.
    Is the automatic air conditioning wiring system diagram. In the air compressor compressor A part of the measurement, A voltage of 12V, that is, air conditioning compressor clutch voltage of 12V, while the ECU output, that is, B voltage is 12V. It is judged that the air conditioning compressor relay does not pull, the system is not unusual, mostly the problem of the relay itself. Break down the relay and see it immediately. The original is the relay contact after stripping the middle of the two contacts in the middle of the bracket, as a conductive state, due to the problem of air conditioning compressor relay, air conditioning compressor no matter what time is connected to the running state. If the indoor air conditioning switch co-operation and the normal operation of the state is no different; if the indoor air conditioning switch is off, because the electric fan does not turn, the refrigerant medium becomes high temperature and high pressure state, safety valve fuse, refrigerant The medium is ejected.