Should I Switch Off The AC Before Starting or Stopping The Car?

Should I switch the AC off before starting or stopping the engine of the car? It is a common question and totally worth investing time to investigate. There are many people who suggest both scenarios, i.e., you should and should not turn the AC off. We shall try to understand the logic behind it and find the answer for ourselves. If you are also concerned about such interesting topics, make sure to head to the Automobile Technology section of the Car Blog India website to clear your doubts regarding various aspects of your vehicle. Let us dive into this post for now.

Also read: Do Diesel Engines Lose Power and Mileage After Few Years?

Switch AC Off Starting

Should I Switch Off AC Before Starting My Car?

There are two ways of looking at it. This idea is old and comes from a time when the cars’ fuel injection systems used carburetors. During those times, the technology was not too advanced to allow the engine to supply power to various components easily. Hence, the power needed to start an engine was getting diverted to AC or other components. That was not ideal since the starter required most of the power to get the engine going. The warm-up of the engine is essential since it controls all the other parameters of the engine, especially the emissions. But now the emissions regulations have become extremely stringent. Hence, technology has also been developed to tackle these issues.

Also read: What Happens if You Drive With Low Tyre Pressure?


In modern cars, the ECUs (Engine Control Unit) control all the aspects of a vehicle. They take care of all the electronic components of a car. The components are in constant communication with one another and the signals are sent and received at lighting speed. The modern cars’ ECUs prioritizes the operations systematically. This means that when you start your engine, the power is not diverted to AC or other areas even if it is switched on. You must’ve noticed that while starting your car, all the electronic equipment gets temporarily switched off. The power is directed towards the starter and the battery is available to supply the power to the other components soon after. So, if you switch off or on the AC of your car while starting the engine, it will not affect anything in the car. However, if you own an old vehicle, it is a good idea to do so.

Also read: Here’s How to Easily Check Your Car Tires’ Health