Start Car With Ac On

Miyuru Daminda · January 28, 2009

Hi all,

Normally I never switch off my car's AC but my friend told that start the car with AC in on position will ruin my engine. Is it really true? or just a myth?

tharindu6 · January 28, 2009

Hi all,
Normally I never switch off my car's AC but my friend told that start the car with AC in on position will ruin my engine. Is it really true? or just a myth?

well in good old time that was the commen practise. But the new cars that came after 1989/1990 have a cut off sorta switch.when you trun the ignition the a/c,radio and other equpments that draw lot of power gets disconnected automatically and then reconnects after the engin starts.

Im suere our AL members will be able to answer you more clearly and methodically :rolleyes:

Devinda_Z · January 28, 2009

"ruin your engine" is rather harsh..

but out of sheer habit i keep it off when firing up the engine - reduces the load , or so i was led to believe :unsure:

miniace · January 28, 2009

Correct...all unwanted electricals get cut-off during ignition applications including ac and ac system.

MINIACE

JadeyBlitzen · January 28, 2009

but i never figured out why its hard to start a diesel car with the a/c on. especially when the battery has aged a bit.

i havent noticed this on petrol cars but i've been warned against starting cars with the a/c on.

can someone please explain this?

Supra_Natural · January 29, 2009

but i never figured out why its hard to start a diesel car with the a/c on. especially when the battery has aged a bit.
i havent noticed this on petrol cars but i've been warned against starting cars with the a/c on.

can someone please explain this?

The cranking power required from the battery for a diesel vehicle is higher, therefore naturally the load on the battery is more. Older batteries find it difficult to provide adequate cranking power when the accessories are on.

Ruslan · January 29, 2009

The cranking power required from the battery for a diesel vehicle is higher, therefore naturally the load on the battery is more. Older batteries find it difficult to provide adequate cranking power when the accessories are on.

I guess that explains why Diesel vehicles got higher Amp equipped batteries than their Petrol counterparts.. :rolleyes:

charitha19 · January 29, 2009

yeah, if u have a old car this is true.. it wont ruin the engine.. but it will make it harder on the crank.. the newer ones dont have this problem. u can test this.. just put the fan on, not the AC.. and crank the engine.. u will see for the moment that the starter motor is running ur fan and other stuff will be off.

maliths · January 29, 2009

well in good old time that was the commen practise. But the new cars that came after 1989/1990 have a cut off sorta switch.when you trun the ignition the a/c,radio and other equpments that draw lot of power gets disconnected automatically and then reconnects after the engin starts.
Im suere our AL members will be able to answer you more clearly and methodically

Yes this is correct. All the electricals turn off on new cars. Even in older cars it wont ruin the engine but makes it difficult for the starter motor.

JadeyBlitzen · January 29, 2009

The cranking power required from the battery for a diesel vehicle is higher, therefore naturally the load on the battery is more. Older batteries find it difficult to provide adequate cranking power when the accessories are on.

probably due to high compression levels of diesels i suppose.

thanks guys! great info