Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 25th April 2008, 11:09   #1
BHPian
 
devnull's Avatar
 
Join Date: Nov 2007
Location: Hyderabad
Posts: 142
Thanked: 9 Times
Default Switch engine off or on to make A/C effective?

Hi,
I have this basic doubt which became more intense when my better half made me wait outside her office for 45 mins yesterday . We know that the A/C cooling system becomes effective only when the engine is running. So what should be the best way to keep the car cool when you are inside with the engine off for a long time? - Should we start the engine or keep it just in On mode and make do with the heat? I can understand keeping the engine running if it's just a matter of minutes, but what about long waits? I have seen cab drivers sleeping inside their cars in the afternoon with the engine running to make the A/C effective. Is it the right thing to do? Which hurts the FE more?

With the mercury rising rapidly these days, I think I need a good solution to this immediately.


Thanks,
Rahul
devnull is offline   Reply With Quote
Old 25th April 2008, 12:17   #2
Distinguished - BHPian
 
Technocrat's Avatar
 
Join Date: Feb 2004
Location: Mid West
Posts: 14,900
Thanked: 2,492 Times
Default

In the current heat wave(Pune is 42 deg :() I dont think there is any alternative. You can off course park under shade & be slightly better off. Switching ac on & off will make the inside more humid & ac working double to compensate for the off time.
Technocrat is offline   Reply With Quote
Old 25th April 2008, 12:19   #3
Senior - BHPian
 
esteem_lover's Avatar
 
Join Date: Jul 2006
Location: Madras/Py
Posts: 7,554
Thanked: 445 Times
Default

Best is to get out of the car & wait outside under a tree. Idling your car with AC for extended periods is certainly not a good thing for your car. Engine is bound to get more heated up.
esteem_lover is offline   Reply With Quote
Old 25th April 2008, 12:32   #4
Senior - BHPian
 
Join Date: Apr 2007
Location: Pune
Posts: 2,453
Thanked: 955 Times
Default

Yes, if wait time is more, why wait inside the car?
Kindly be considerate to mother nature as well.
An idling engine with A/C on is definately going to cause a lot of pollution.

The A/C is driven by the engine through a magnetic clutch. So even if engine is off, this clutch will be engaged as long as your battery has the charge, though the A/C compressor will not run as the prime mover (the engine) is off. Hence, if you need A/C to do it's job, you need the engine running.

Last edited by anandpadhye : 25th April 2008 at 12:33.
anandpadhye is offline   Reply With Quote
Old 25th April 2008, 12:43   #5
Senior - BHPian
 
Surprise's Avatar
 
Join Date: Feb 2005
Location: Chennai
Posts: 2,299
Thanked: 129 Times
Default

Quote:
Originally Posted by anandpadhye View Post
An idling engine with A/C on is definately going to cause a lot of pollution.
Few cases of deaths has been reported due to keeping the A/c on with idling engine for long hours.
Surprise is offline   Reply With Quote
Old 25th April 2008, 12:43   #6
Senior - BHPian
 
Join Date: May 2007
Location: Bangalore
Posts: 3,652
Thanked: 244 Times
Default

The Office reception is a good place to wait than the car, if it is going to take longer.

Quote:
Originally Posted by anandpadhye View Post
Yes, if wait time is more, why wait inside the car?
Kindly be considerate to mother nature as well.
An idling engine with A/C on is definately going to cause a lot of pollution.

The A/C is driven by the engine through a magnetic clutch. So even if engine is off, this clutch will be engaged as long as your battery has the charge, though the A/C compressor will not run as the prime mover (the engine) is off. Hence, if you need A/C to do it's job, you need the engine running.
dadu is offline   Reply With Quote
Old 25th April 2008, 13:02   #7
Distinguished - BHPian
 
supremeBaleno's Avatar
 
Join Date: Dec 2005
Location: Weekdays@Chennai, Weekends@Kerala
Posts: 5,164
Thanked: 1,638 Times
Default

I go with dadu here - the reception would be climate-controlled. Why waste fuel idling a car just to keep you cool, when you have better env-friendly options ? Or as others said, find some tree or shade (not shady place) nearby.

As a policy, I never ever idle the car just for the a/c. But recently have had to break it for my li'l kid due to the weather in Kerala being pretty hot and with no sign of any rains.
supremeBaleno is offline   Reply With Quote
Old 25th April 2008, 13:38   #8
Senior - BHPian
 
narayan's Avatar
 
Join Date: Aug 2006
Location: Singapore
Posts: 2,772
Thanked: 1,166 Times
Default

firstly , i am not sure what are the 2 options being suggested here to keep the car cool ?

i always thought there is just one option - keep the engine on and the a/c running ? is there any other way to run the a/c ( not just blowers ) ?

wheareas, a/c on idle causes pollution etc, i wonder whether that pollution is any different from pollution caused with car on the move and a/c running ?

all though i normally dont do this, i did use the a/c with my engine on neutral for nearly 35-40 mins when we had to wait in the scorching delhi heat and no shad(y) place or office receptions nearby..
i did not notice any dramatic drop in FE for that particular full tank - in fact i almost got the same FE as i get otherwise...

of course, if you have a diesel car, then its really easy on the wallet - ive seen many diesel car owners not even switching off their cars when they go to do some shopping !!
narayan is offline   Reply With Quote
Old 25th April 2008, 13:48   #9
Senior - BHPian
 
Chevy_lover's Avatar
 
Join Date: Mar 2008
Location: Köln
Posts: 1,209
Thanked: 121 Times
Default

I usually never switch off my engine and AC, when the waiting time is less than 20 minutes. Pune is getting hotter by the day and it is unbearable at times!

Finding a shadowy place is not possible all the time. I never switch off my engine and AC at signals also. There is no dramatic drop in FE because I leave the engine on.

Someone told me that the engine consumes approximately 1 litre of fuel for every hour of idling with AC. Is it true?

During my past trip to Kerala, I slept for two hours in my car with the engine and AC on, because of the mosquitoes and humid weather!
Chevy_lover is offline   Reply With Quote
Old 25th April 2008, 13:58   #10
Senior - BHPian
 
srishiva's Avatar
 
Join Date: Nov 2006
Location: Bengaluru
Posts: 3,580
Thanked: 823 Times
Default

Quote:
Originally Posted by Chevy_lover View Post
Someone told me that the engine consumes approximately 1 litre of fuel for every hour of idling with AC. Is it true?
I have heard its 10 ml per minute on average.

Bangalore currently is like 33 degrees with 30% humidity and cool winds (winds are never warmer here anyway).
srishiva is offline   Reply With Quote
Old 25th April 2008, 14:58   #11
BANNED
 
Join Date: Jan 2007
Location: NAMMA BENGALURU
Posts: 5,613
Thanked: 2,460 Times
Default

Sri,

Its touched 37 degrees on Wednesday.

I agree with you, Bangalore was never hot earlier.

Using AC during Idling will only result in Engine Damage/Polluting environment and Global Warming.

I see other options given by TBhpians more appropriate to act upon.
PAVAN KADAM is offline   Reply With Quote
Old 25th April 2008, 15:09   #12
Senior - BHPian
 
vnabhi's Avatar
 
Join Date: May 2007
Location: DC -> DC
Posts: 5,271
Thanked: 1,236 Times
Default

Quote:
Originally Posted by PAVAN KADAM View Post
Sri,

Its touched 37 degrees on Wednesday.

I agree with you, Bangalore was never hot earlier.

Using AC during Idling will only result in Engine Damage/Polluting environment and Global Warming.

I see other options given by TBhpians more appropriate to act upon.
Can you please elaborate on engine damage during idling? I did not hear about this before?
vnabhi is offline   Reply With Quote
Old 25th April 2008, 15:27   #13
Distinguished - BHPian
 
supremeBaleno's Avatar
 
Join Date: Dec 2005
Location: Weekdays@Chennai, Weekends@Kerala
Posts: 5,164
Thanked: 1,638 Times
Default

Quote:
Originally Posted by srishiva
I have heard its 10 ml per minute on average.
You are right - for 10mins of idling, 100ml of fuel is wasted.

Quote:
Originally Posted by PAVAN KADAM
Its touched 37 degrees on Wednesday.
Hmm, that's flaming hot by Blore standards. Chennai seems a better option.

Quote:
Originally Posted by vnabhi
Can you please elaborate on engine damage during idling? I did not hear about this before?
Google and you will get your answer. It is basically about the lower operating temperature being bad for the engine.

To quote from one of the links,
"In fact, idling longer than that could actually damage your engine in the long term. Because an idling engine is not operating at its peak temperature‚ the fuel does not completely combust, leaving residues in the engine that can contaminate engine oil and make spark plugs dirty. Excessive idling also allows water to condense in the vehicle’s exhaust, contributing to corrosion of the exhaust system."
supremeBaleno is offline   Reply With Quote
Old 25th April 2008, 15:30   #14
BHPian
 
Join Date: Jan 2007
Location: Trivandrum
Posts: 79
Thanked: 0 Times
Default

Quote:
Originally Posted by Chevy_lover View Post
During my past trip to Kerala, I slept for two hours in my car with the engine and AC on, because of the mosquitoes and humid weather!
It is very dangerous to sleep inside the car with AC on. If there is some smoke coming inside the car because of some malfunction, it can easily kill you. All the more reason because you are sleeping, you will not notice that the carbonmonoxide level inside the car increases.

If it is inside a closed enclosure, it is even more dangerous. One year back an incident happened in Trivandrum which killed three youngsters inside their car shed which had no air circulation. They had the car AC on and had some party inside the car.
carlover98 is offline   Reply With Quote
Old 25th April 2008, 15:32   #15
Senior - BHPian
 
Chevy_lover's Avatar
 
Join Date: Mar 2008
Location: Köln
Posts: 1,209
Thanked: 121 Times
Default

Quote:
Originally Posted by carlover98 View Post
It is very dangerous to sleep inside the car with AC on. If there is some smoke coming inside the car because of some malfunction, it can easily kill you. All the more reason because you are sleeping, you will not notice that the carbonmonoxide level inside the car increases.

If it is inside a closed enclosure, it is even more dangerous. One year back an incident happened in Trivandrum which killed three youngsters inside their car shed which had no air circulation. They had the car AC on and had some party inside the car.

My God!!!

Thanks for the info bro!!! Really appreciate it!

I slept in a petrol pump as no good hotel was available for the next 50 kilometres.

Last edited by Chevy_lover : 25th April 2008 at 15:39. Reason: Typo
Chevy_lover is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
AC Switch OFF or Blower Switch OFF Peter Technical Stuff 24 29th June 2011 12:02
Engine switch-off procedure in cars rr_zen Technical Stuff 65 10th December 2009 21:55
Do you switch engine off soon after reaching destination? vnabhi Technical Stuff 15 18th January 2008 17:24
Do you switch your system off before shutting the engine down? kb100 In-Car Entertainment 29 17th June 2006 14:55


All times are GMT +5.5. The time now is 10:23.

Copyright ©2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks