I have a 2005 off-peak car that has a mileage of 70,000km. When I switch on the air-con, the engine will start to vibrate. What is the problem?

Saiman

When you switch on the air-con, there is an additional load (air-con system) added on the engine. Under normal circumstances, the engine speed will automatically increase (by default) to compensate for this additional load, otherwise the engine idling speed will decrease and cause vibration.

If the vibration was due to a drop in engine idling speed (rpm), you will need an engine tuning for your car. You may check the following items:

• Idle air control valve
  
• Idle speed control actuator
  
• Engine coolant temperature sensor
  
• Throttle position sensor

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