Modern car no need off
Keep the ac always on

Car will auto add time delay before engaging the compressor

TOTALLY depend on what car you drive.

i don't warm up car in morning.
my air cond auto start right after car started.

no problem at all.
my current car, my last car.

maybe quality built

It’s just a car, a consumable item, something that won’t stick around with you for long anyway - let those 2nd hand owner worry about it.

For me, i only press ON/OFF switch, the rest all leave is as auto. I use a car the way how i wanted to, sometime just start car already speed away, or rev rpm until 4-5k because rushing. I’ve been through 5 car - all zero problem.

Best guide is your car user manual

In previous years a lot of old mechanic did not recommend to turn on the A/C in cold state because of those old carburetor cars which did not got the so call vacuum solenoid switch which will help pull in air to increase the rpm. If your car condition is bad it may stall or hard to accelerate or drive.
Only later modern cars got all these solenoid switch or electronic throttle body so it is not a problem nowadays.

This post has been edited by littlefire: Dec 3 2021, 08:41 AM

The main reason to off air-cond is that so you have whole battery cranking power to crank the engine. If air-cond is engaged, it will put a toll on the battery.

As you know, the air-cond compressor is engaged by its clutch. In modern car nowadays, even my Axia, there is timer to delay clutch engagement. Even if you left the air-cond switch on and start the car, the clutch will not engage. Once the engine is running, after few seconds, the clutch will engage and you can feel cold air already.

No need to wait or even off the air-cond switch. I've never had the switch off for several cars I've ever owned and never had problem due to it.

I never bother to switch off anything before I turn off the engine
Cause I never want to switch on anything after I start the engine

Start engine then drive off in less than 10 seconds...
10 seconds to wear seat belt, release handbrake, check check side & rear mirror...

I guess I'm too lazy to wait...

turning on aircon after start will add burden to your engine once the clutch engaged. personally i think this is good to speed up the engine warm up process.

whether is required to turn off the ac or not when u turn off the engine.. this can be an optional. Modern car will delay ac from starting when u first crank ur car. If that mechanism is working fine then all good. For me i will still turn it off to conserve battery during cranking as with ac on the blower will run when u r in acc mode. Personal habit thou.

If your don't touch that switch, no damage to engine or compressor

If you keep turning on and off, still no damage to engine or compressor,.
But your switch will Kong first

I see i see. Thank you all for your inputs. 👍👍 i think that answers my question well and good

so what your decision? as i read all, starting tomorrow i will just leave aircond as ON never OFF.

Until today, I practise and fully off before I switch the engine off.

My cars’ air cons are all set to automatically turn on all the time. So far no issues. No battery warnings.

Newer cars these days will automatically cut off aircond when starting to protect the engine, compressor and battery. Last time there is no cut off that's why we need to turn it off. Also, turning things off before turning off the car put less load on the engine. Is like someone suddenly pour water on you.

Mine if I leave the aircond on and radio on.. when starting it tends to pull more from the battery as there are too many things running.

I saw posts like this come out once in a while.

People that telling you not to on air cond, not to on car stereo while starting the car are coming from much older generation where cars still using old engine without ECU and computer. In those days, yes, this is true.

In modern car (like past 10-20 years after using ECU), this does not matter anymore, you can keep your air-cond, car stereo on when you switch off your car. Did you even notice, when you try to start your car = all your car electric appliance went into silence / off modes automatically? this is the way ECU control = it will not connect the other electric devices and focus all energy in starting your car. Once you start your car, all electrical component back to life.


It does not matter at all. Dont listen to those peoples, they are using 40 years ago knowledge for today modern car.

Hope this help.

100% true, i tired to see ppl still asking this question in today modern car.

I turn on the aircond before I start the car; my car has that feature where you can turn on the engine before getting in, and I use that every day.