1. air conditioning system failure: if the whole air conditioning system fails, the switches and other control buttons on the air conditioning control panel will not light up. In this case, it is necessary to find professional air-conditioning maintenance personnel for maintenance.
2. Air-conditioning panel failure: If other buttons on the air-conditioning panel can still work normally, but the AC switch is not on, it may be caused by panel component damage or failure. At this time, the panel part needs to be replaced or repaired.
3. Air conditioning switch failure: If the panel switch works normally but the AC switch is not on, it may be that the switch itself or the circuit connecting the switch is faulty and needs to be replaced or repaired.
4. Vacuum switch failure: Some air-conditioning systems have vacuum switches, which will detect the pressure inside the car and turn on or off the air-conditioning system at an appropriate time. If the vacuum switch fails, the AC switch will not start and the vacuum switch needs to be replaced.
In short, if the AC switch of Chang 'an Ounuo air conditioner doesn't turn on, I suggest you check the air conditioner panel and switch components first. If it can't be solved, you can consult professional car maintenance personnel.