Hi guys, as per title above, is it okay to on my aircon the moment I start my car cold, like first start of the day before I head off to work. I know it might be a dumb question to ask, just that some folks at home have told me not to immediately on A/C when you start your engine, which assumingly, they're referring to parasitic load on the engine I guess...

I have a habit of driving the car for a while, (approx 10-15mins) before I turn the A/C, but sometimes the sun is unbearable. Which begs the question above.

Thanks all!

I can understand your situation,

For me, the soonest would be after start the engine, wait till all the check lights on the multi info display turns off, normally less than 10 seconds.

If temperature not hot & I'm not in a rush, i will wait till the engine has warmed up a bit. Less than 1 minute

Yes, it's ok. If it's not ok, the car manufacturer would have put that in the user manual.

Aircon will always be a parasitic load to the engine, no matter when you turn it on. If you're worried about extra load on the engine when cranking, most cars will disable high loads (aircon/audio) when you crank the engine.

Ahhh, I see I see.

Yes, I think it make sense waiting for a minute or 2 before turning the A/C. By then, our Engine Oil has already done its job travelling around the engine. Thank you for your input.

you suffer too long waiting for 10-15min before ON the air-con... lol

i think the moment you decide to put D gear to drive your car you can ON the air-con already.

I think modern car when you maintain properly with oil & filter changed on schedule, there r minimal damage. If you want better protection, use 100% fully synthetic oil.

No problem, i never switch off ac when turning off the engine also

This post has been edited by arza04: Dec 2 2021, 10:25 AM

Modern cars can just switch on the air cond the moment engine is started. You can even leave it on and switch off the engine so that the air cond is turned on the moment you start up the car.

there is no right or wrong answer to this, it all boils down to what you feel is right.

if you are worried about whatever you call parasitic load from engine, a lot of people turn on their aircon, turn down there window, i think its a good way although i suspect the main reason is so the heat can dissipate faster.

but i guess it serve your purpose while minimizing your concern.


edit: sorry i misunderstood the term parasitic load, i thought its the smell, or chemical from the aircon system left overnight.
in that case, like others said, turn on your aircon after startup, or after car warm to operating temperature should do.

This post has been edited by cempedaklife: Dec 2 2021, 11:09 AM

By folks I presume you are refering to 'old' folks who may be driving cars in 70's and 80's with after-market (reciprocating pistons) air-cond system?

The 'rule' doesn't quite apply to factory-installed (rotary) air-conds for the past 3 decades (or so) I suppose.

I switch on after starting the engine. No issue so far after 10 years.

Can explain the bold part? You mean leave the aircond system on before you even crank the engine, and crank it regardless? Or do you mean aircond system is off before crank engine, and switch it on after engine is running?

Even the big old 4.0L, 5.0L V8 start circulating engine one immediately, and complete full circulation in less than 7 seconds.

Small 1.5L, 2.0L engine probably take half the time. And modern engine with low viscosity engine oil and variable load engine oil pump would be even faster.

If you really worry, wait 7 seconds. Actually no need at all, modern car automatically off the aircond during start. On top of that, due to environmental protection the engine will run higher rpm during cold start to warm the catalytic converter ASAP. Why was the extra power generated during the time.

On top of the on top of that, modern AC compressor is variable displacement without magnetic clutch. AC doesn't just on/off. They are actually not new, some 10 years+ old cars already have it. Japanese should start using them over 5 years ago.
https://www.toyota-industries.com/products/...essor/variable/

On top of the on top of the on top of that, we now have electric driven AC compressors that not coupled to engine belt. Used to be only Hybrid, PHEV, EV, but now we have 48V vehicles also use them.

My GT aircond switch is left to ON all the time. Mileage above 300k km with stock compressor working well.

Yes.

Some cars like Peugeot won't let u turn on the AC unit the engine already reach 90C. So, under a hot afternoon, u need to let it warm up for 5-6 mins which is a stupid design and waste fuel.

For me, since I have OBD and torque app,
I usually drive+warm up the car till the water temperature shows at least 50C,

For other cars, it's usually the temperature bar has at least gone 2 out of 3 bars.
Or wait for the Blue light (for my Axia, which is after 50C) to go off.

Cause by turning on the aircond, obviously the radiator fan kicks in = engine warms up slower.
And added stress to cold engine.

make no diff lo. things that design to spoil will spoil anyway.

radiator cold tapi thermostat not flowing cold water into enjin yet
so haha

Thank you for all the informative replies, guys. Since I'm new here, LYN forum system limits the number of replies I get per day.
Like if cold mornings I don't mind la, driving without the A/C. With the warmer months approaching, I would like to just switch the A/C on so when I arrive office also, a bit cooler la.

Also, I'm driving old Proton Satria Neo (Non-CPS) version, if it helps. haha. Don't know whats the A/C system in there. Gonna assume its also a modern system la since its a 09' car.

@zeng, Yeah old folks at home, y'know la, parents, grandparents, aunty and uncles.

@speedy3210, Means the moment you get into the car, turn the key, and turn on your aircon, (in immediate succession) first thing in the morning.

Bro, they were absolutely right in what they said and they were truthful to you.

I would have said what they said too ....... for that was the golden truth/relevance then.

May be I'm a bit more keeping abreast with evolution of car air-cond 'technology' (and I'm currently fallling behind already) compared to your folks.

Go inside car ---> open aircon --> start jalan

Rosak change/ send for repair jer.... risau ape bossku

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.