A Shanghai Passat B5 sedan, the user reflects the car air conditioning when good and bad, while blowing cold, while blowing hot air, air conditioning control panel in the open ignition switch, there will be regular flashing 15s, indicating that the air conditioning system is faulty.
    Connect the fault diagnosis device to check the air conditioning system and find the fault code 00792, the fault is: the air conditioner pressure switch F129 and its line failure in the record of the fault code, remove it, start the vehicle again, the initial air conditioning effect Very good, but soon to die, but also a while cold wind, while blowing hot air. Again using the fault diagnosis instrument to detect the air conditioning system, the system still exists 00792 fault code, it seems that the pressure switch F129 does exist fault. For this reason we will replace the sensor, but the replacement of the sensor after the test, the fault remains the same, and 00792 fault code still exists.
    Just replace the sensor can certainly be good, the fault code can also be removed, so that the control unit should not be a problem. After further understanding to the user, that the car in the cold when the air conditioning effect is good, hot car will appear for a while when the cold wind, while the phenomenon of hot air. According to the information provided by the user, maintenance personnel suspected air conditioning and refrigeration system cooling bad. So open the engine hatch and found that air-conditioning electronic fan actually did not open with air conditioning, it seems the cause of the fault lies in this. Unplug the electronic fan connector and found that the conductive contact of the connector has been severely ablated. In the direct operation of the electronic fan, the electronic fan work well, open the air conditioning when the power to the plug, indicating that the problem is that the plug bad.
    After the treatment of the plug, and then open the air conditioning, electronic fan immediately run, the cooling system is working properly, connect the fault diagnosis instrument to detect air conditioning system, and then did not find the fault code, the fault completely ruled out.
    The system will appear 00792 fault code, because the electronic fan is not working, resulting in poor system cooling, resulting in high temperature refrigerant, making the system pressure is too high, the air conditioning control unit mistakenly believe that the pressure switch is bad, and recorded The fault code. Therefore, if the simple repair in accordance with the fault code, is not able to rule out the failure.