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-   -   Switching on Your AC in Cold Start (https://www.team-bhp.com/forum/technical-stuff/27321-switching-your-ac-cold-start-4.html)

I used to switch on the AC immediately after starting till recently. Now (after reading about it in this forum) I have switched to 1-2 mins after start, when the engine temp indication springs to life.

lol: Actually I never need ac. Does switching on the heater Immediately on a cold start affects the engine????

My way.... 2-3mins after start.... but depends on the weather.... i.e. how quickly will the engine heat up...

But I always give it time. AND that's Delhi Heat ...

I dont think it would because heater uses power from battery & not does not need compressor which draws power from engine.

Experts can correct me if I am wrong

The types of Heaters we have in cars are not electric... it runs on engine coolant. So technically you won't even get hot air till the engine heats up.

I think heater takes residual heat of the engine, from it's cooling system.

when at low temperatures, I guess it would be wise to let the engine temperature rise to normal (the middle of the temp gauge, i am guessing 200C) and then turn on the heater....else engine will not warm up early enough.

OH thats a news for me. Why I had said this was because I knew one of my friend had got a heater element fitted in his Non Ac M800(very old model around 90s) for winters.

Most of the time i avoid using the AC if the weather is fine... But there are not many days like that in delhi.... and if the weather is hot and humid, like it is these days, i have to start the ac as soon i start my car... Any delay and i would be swimming in my car...
P.S. No rear window opening for me... Manual windows, so cant hlp it... But i do roll the front windows down for about 45-60sec... Hastens the cooling...

I don't have an Esteem anymore. I had an M1000 (1991 model), which also used to knock off all power to everything else except the starter circuit. Also seen it in elfy's Alto Lx & Mom's Alto Vx.

Heres some thing to think about - maximum engine damage takes place when cars are first started in the mornings or after a after a long time of inactivity where the oil from the engine settles down into the sump. Experts have estimated that starting an engine - cold start, dry start - whtever you want to call it ammounts to about 800 Kms of regular drving. so the folks who get into their cars and start the aircons before even starting their engines or to those who switch on their aircons immediately after startup - YOU SURE HAVE SOMETHING TO THINK ABOUT NOW. If you want your engine to last you will need to look after it. Switch it on, idle it, warm it up and then start driving. Just like we warm up or stretch before working out our engines need to do the same also.

Also remember that synthetic oils take the least time to circulate and provide superior engine protection when compared to mineral oils. Weather in Chennai is almost the same thru the year, but for our friends up north i would sincerely recomend that you shift over to a thinner grade of oil during the winter.

Regarding corelation between a/c blower speed and FE - Yes it does effect fule efficiency but there is a better explanation - There is a cooling coil behind the dash board just as there is in the airconditioners in your house. Compressed gas in passed thru the coil thereby dropping the temperature in the coil and the blower when switched on draws air thru a chilled cooling coil therefore provoding us with cool air. This cooling coil has a Bulb or a thermostat or a sensor. When the blower is running at a lower speed the coil gets colder faster and thus triggers the thermostat which in turn switches off the a/c compressor. When the blower runs at a higher speed the air is drawn out at a fatser rate and therefore the temperature of the cooling coil does not drop very quickly thereby running the compressor for longer periods of time. I dont know if you guys have noticed - When you take your car to an a/c mech he will always check the grill temp with blower at minimum fan speed. Notice next time you are at your local workshop.

Take care of those engines guys. They serve you better, Longer even.

Thanks, sideways. That was pretty informative. Will make sure I let the engine idle a bit before take off and switch on the a/c only after the temp gauge shows a decent reading.

And BTW, congrats on becoming a "Distinguished BHP'ian". clap:

As stated before, my A/C switch is always on. This, however, doesn't mean I don't wait for the engine to idle for a while and warm up before I start driving. I'm just clarifying the difference between taking off immediately after starting and starting with the A/C on.

A question for the experts - if, say, my car idles at 800 rpm without A/C and at 1000 rpm with the A/C, how much difference does this make in the wear and tear?

No expert here... but.. its not the question of RPM... its the load. You can drive in 5th gear at 800rpm... is that as good as idling without load?
AC is always a substantial amount of load on the engine.

Sirji that was for Esteem Lover & not you :)

But doesnt that mean it will take longer time to cool the cabin ? Which in turn means it will take more time for sensors to pick the desired temperature & switch the compresor off later than sooner ?

This will mean the coolness will spread fast & the sensor will register desired tempreature faster & hence turn of comp earlier.

As for the mechs they notice how much time it takes on 1st speed to reach a temperature since at low speed the concentration is higher & ther readings can be taken faster

My conclusions are based on assumption that the switch off sensor is somewhere in cabin (i.e. its taking cabin temperature & not coil temperature). If the sensor is near coil then what you say holds true

elf, i too had a 1993 1000 for a long time & even it seemed to cut off the power to everything when you crank, but the same car has also cranked the engine without cutting off the ICE. the same applies to my present esteem & my previous (2000) esteem as well. i feel that depends on the condition of your battery at that point of time.

for e.g. on wednesday night, i drove the car with AC for almost 2 hours in the stop/start city traffic. on thursday morning when i started my car for the first time, my ICE's power got knocked off. whereas on thursday, i drove only for 10 mins in the night with ac & drove 1 hour in the day with ac, which helped to keep my battery in full charge, as a result, when i started my car today (friday), the ICE did not get cut off. i tried starting again & the same result.
:)