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Old 5th July 2012, 20:31   #61
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Default Re: Can we switch ON AC, while engine starts?

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Originally Posted by powerwidFE View Post
Today I managed to stall my car with aircon ON in slow moving traffic. In a hurry I tried to fire the engine without switching the aircon OFF( so that the blower was still ON at speed 2). Normally, my WagonR starts at half crank,but this time it didn't. The engine fired up and then died(The clutch was pressed down all this time,so it couldn't be the normal clutch released too fast or wrong gear issue). This happened twice(and not to mention the innumerable honkings I got from behind! ).
Then I switched off the blower and cranked.Voila! It started at half crank.
Probable reason is a bad battery. With AC on, cranking is slower, as the battery has to turn the engine as well as power the compressor, and hence takes more time.

Last edited by dhanushs : 5th July 2012 at 20:32.
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Old 5th July 2012, 22:19   #62
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Default Re: Can we switch ON AC, while engine starts?

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Gurus,does this throw any light on whether or not we should have the AC on during cranking?
powerwidFE, I normally switch off all lights/AC/blower/Stereo before starting the car. That said, my car has never failed to start if I inadvertently attempt to start it with the AC on.

I would suggest switching off the AC when you are starting the car. Having the AC compressor engaged and the blower running when starting the engine puts an additional load on the starter motor and battery.

If this behaviour is new, I would suggest getting an ignition system check and a battery load test.
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Old 5th July 2012, 22:44   #63
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Default Re: Can we switch ON AC, while engine starts?

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Originally Posted by powerwidFE View Post
Today I managed to stall my car with aircon ON in slow moving traffic.
====
Gurus,does this throw any light on whether or not we should have the AC on during cranking?
Check battery first, normally when engine switches off the AC is cut off and will kick in only after the engine is running. Another reason can be the electrical radiator fan would have been also ON at the same time and that was putting additional load on the weak battery.

So my advice, get battery checked, terminals cleaned first. Next would be to check the starter motor health.
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Old 5th July 2012, 22:48   #64
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Default Re: Can we switch ON AC, while engine starts?

In my wagonR when I turn the switch little after ignition on position (just before cranking) all electrical including blower, ICE etc switches off and turn on only after engine is started. However the headlights will not turn off as it is not connected with ignition switch so you have to take care of that.

Sometimes people switch off the engine during red lights at night but don't turn off the headlamps which drains the battery and other special effects follows.

So this generally applies to all cars on sale today!

But even if some of us(including myself) switch off the A/C button (A/C is already switched off - IT CAN NOT RUN ON A 35AH BATTERY :P) before starting the engine then it will not do any harm, in fact it will help in maintaining our BP .
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Old 7th July 2012, 15:47   #65
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Default Re: Can we switch ON AC, while engine starts?

In my wagonr, AC compressor is cutoff before cranking the engine. The compressor starts two seconds after the engine starts running.
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