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Old 12th August 2010, 14:19   #16
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Originally Posted by ilangop View Post
The Engine ECU takes care to cut-off the AC compressor when the Accelerator pedal is suddenly floored.

Even in carburetted engines there use to be a limit switch at the accelerator pedal. This switch cuts off power to the AC compressor clutch as the pedal goes beyond certain position.
You dont have to manually switch off the compressor if everything else is in place.
Well, ilango, I'm not so sure of that. Atleast in the 800, Zen and Alto, as Gansan mentioned, there is a clear boost of power when you switch off the compressor. Even though the car is in full throttle, the 'boost' is very much evident.

but, thank you for the info, as I didn't know that this existed in cars. However, in my Ford Ikon, when the blower is in the min position, and the car is idling, I can hear that click and change in engine load(rpm), this happens irrespective of the throttle position.

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Originally Posted by ph03n!x View Post
Close to what @dhanushs has suggested - but instead of the blower speed, set the temperature control (the dial with the blue for cooling and red for heating markings) to the minimum possible in the blue area so that it is not too uncomfortable. The blower runs out of the battery, and hence does not make any difference in the engine's load - it is the compressor runs off engine's power. And I am assuming that the car will disengage the compressor when corresponding temperature you set using the dial is reached.
ph03n!x, Atleast in my car, if we change the temperature knob into a lesser temperature, the car does not switch off the compressor, instead, it mixes hot air to the cold air. There is a valve just below the wiper mechanism inside the bonnet which does this. That is why, I guess it is not advisable to put the temperature in high with the AC switch on. If you need hot air, switch off the compressor.

However, the method you suggested must work perfectly on cars with climate control. They have sensors inside the cabin to sense temperature and adjust the blower/compressor accordingly.

Quote:
Originally Posted by saurabhnanda View Post
How tough is it to simply get the compressor replaced to a smaller one? Will it help reducing the engine load?
As your car is new, that should void the warranty. Also I don't think that would be cost effective. Instead, as esteem_lover mentioned, you can invest that money in a good FFE and K&N.

For the time-being, I guess switching off the compressor is the only remedy.
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Old 12th August 2010, 14:39   #17
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Is it advisable to switch on/off ac while the car is in motion ?
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Old 12th August 2010, 14:48   #18
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saurabh,
there are few operating modes of the figo ac like blower on face, blower on face and feet, blower on feet, demist and a fifth mode.
the pictoral on this mode is the driver seated one arrow towards the face, one arrow towards the feet and one demister. all three together. i have noticed that when i drive my figo in this mode, it gets decently cold and its not chilly. the normal ac operation mode is abnormally cold! even at the lowest setting.

a little about the power loss issue now.
there is a distinct difference in the way diesels and petrols work.
consider petrol engine first. you have a very narrow band of fuel-air ratio in which you can operate in a gasoline. due to this, at a particular rpm, there is relatively fixed amount of fuel which can be sent in the engine. lets say this produces 'x' Nm amount of torque. some of this is spent in driving the accessories (water pump, fan, ac compressor, etc.) call this amount to be 'a' Nm. thus, torque available at clutch will be x-a Nm. simple.

for diesel, the same amount of torque will be available at clutch. but any extra load on the engine (from ac compressor, fuel pump, fan, water pump, etc) will be taken care of by adding EXTRA FUEL. thus x+a fuel.

this is possible because of the ability of a diesel engine to operate over a wide range of air:fuel ratios. thus without the ac, the engine will be using say for example 35mg fuel per cylinder every stroke and with ac, there will be something like 37 mg. you dont feel the power loss as the engine does not starve. the driver simply would have depressed more accelerator pedal or you can have separate maps for drivability with and without ac.

but even after saying all this, i feel the figo sometimes exhibits a surge sort of behavior when picking up from 2nd gear with ac on at speed of 13-15 kmph. that is the only time i feel the engine struggles to regain itself in the entire driving range which i have covered.
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Old 12th August 2010, 14:51   #19
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Originally Posted by esteem_lover View Post
Go for more power. Get a K&N and FFE. That should perk up your Figo.
If TBHP had a feature for picking "best answers", I would have selected this

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Originally Posted by Gansan View Post
Hey, Figo owners are now usurping the copyrighted story of Alto owners! We are veterans in handling this! What I do when I sense the engine struggling (over taking / hill climb with full load) is to quickly switch off the AC and switch it back on after completing the task. We call the AC button our "boost" button!
Nooo... this was my trademark when I had an Indica Diesel! And I used to call it the car with three brakes - the brake pedal, the hand brake and the AC button. The car would do 0-100 in 30 minutes with the AC on, and in about 25 minutes without the AC (Of course I am exaggerating, why not?!! )

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Originally Posted by dhanushs View Post
ph03n!x, Atleast in my car, if we change the temperature knob into a lesser temperature, the car does not switch off the compressor, instead, it mixes hot air to the cold air. There is a valve just below the wiper mechanism inside the bonnet which does this. That is why, I guess it is not advisable to put the temperature in high with the AC switch on. If you need hot air, switch off the compressor.

However, the method you suggested must work perfectly on cars with climate control. They have sensors inside the cabin to sense temperature and adjust the blower/compressor accordingly.
Thanks @dhanushs. The only time I sensed the compressor in my car getting cut off is when I moved the temperature control knob to the middle, exactly between the "blue" and the "red". I don't feel the AC turning on, it doesn't affect the power at all - but I want to explore the possibility of adding a thermostat for convenience, it getting pretty cold no matter what, unless I keep turning off the AC and back on
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Old 12th August 2010, 17:46   #20
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Originally Posted by vnabhi View Post
I guess that 2-minute (actually it is 3 minutes) rule for switching on an AC applies to home ACs and not automobile ACs. I've been switching my WagonR's AC off and on in rapid succession whenever I need more power for the past 9 years, and so far even the AC gas has not been changed. It is still working like a charm.
Anyone else have same experience?
I was coming from the Home ACs and fridge, I thought all compressors had this rule. Was too afraid to try on my car.
I would really like to know if car ACs are diff, and can be switched on and off quickly without any problems.
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Old 12th August 2010, 17:53   #21
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Originally Posted by guptavis View Post
Anyone else have same experience?
I was coming from the Home ACs and fridge, I thought all compressors had this rule. Was too afraid to try on my car.
I would really like to know if car ACs are diff, and can be switched on and off quickly without any problems.
I learnt this long back from a pal who owns an Accent --till then I too was under the same impresssion as you. He used his Accent for 5 years without any issue and later upgraded to a Sonata.

He does not need to do such manoeuvres on the Sonata as the AC does not sap the power of the car. Neither do I on on the Fiesta as the motor is quite powerful and there is no drop in pulling power when the AC is switched on, even when the car is in 2nd gear.

@DCEite---you must be joking!! Imagine people on roads stopping cars all over merely to switch the AC on or off.

Last edited by vnabhi : 12th August 2010 at 17:55.
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Old 12th August 2010, 22:07   #22
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Originally Posted by ph03n!x View Post
I want to explore the possibility of adding a thermostat for convenience, it getting pretty cold no matter what, unless I keep turning off the AC and back on
Very true ph03n!x!. Sometimes it does get real cold even in min setting, and you have to switch the AC off. I too have wished many times, that the process get automated. But then, isn't that climate control all about??..

I guess we will have to devise a cheaper, DIY climate control with a thermostat as you have mentioned. .
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Old 12th August 2010, 23:11   #23
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Originally Posted by dhanushs View Post
Very true ph03n!x!. Sometimes it does get real cold even in min setting, and you have to switch the AC off. I too have wished many times, that the process get automated. But then, isn't that climate control all about??..

I guess we will have to devise a cheaper, DIY climate control with a thermostat as you have mentioned. .
One of these days am gonna visit a known car AC mechanic and see if we can fix something similar to the olden days' thermostat like what we had in our Contessa Classic. As and when I do that, will keep all posted.
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Old 13th August 2010, 00:04   #24
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Originally Posted by ph03n!x View Post
One of these days am gonna visit a known car AC mechanic and see if we can fix something similar to the olden days' thermostat like what we had in our Contessa Classic. As and when I do that, will keep all posted.
I didnt know, the contessa had this feature. However, do keep us posted on updates after you visit your mechanic. It would be really helpful.

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Originally Posted by ph03n!x View Post

Nooo... this was my trademark when I had an Indica Diesel! And I used to call it the car with three brakes - the brake pedal, the hand brake and the AC button.
This description of the Indica just ROCKS!!.. ..
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Old 13th August 2010, 02:18   #25
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It is not a feature of the car per se! We had a superking or something on the contessa, which came with a knob about the size you would see in some amps for bass control - it had the fan speed and thermostat control on it, and the compressor's clutch will engage / disengage based on the thermostat.
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Old 13th August 2010, 07:18   #26
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Quote:
Originally Posted by saurabhnanda View Post
I've noticed that my 1.2 petrol Figo's pick-up drops substantially as soon I switch on the AC. Without the AC, however, the pickup is good (in all the gears).

On the other hand, the AC is extremely chilly. I'm never able to tolerate maximum cooling and most of the time the temperature control is 1-2 points away from the red zone. I hear that the Figo's AC compressor is larger than other cars in its segment.

Is there a way with which one can reduce the load generated by the AC? Is the load constant irrespective of the cooling temperature? I've not noticed a better pick-up with the AC set to lower cooling.
The simplest way to your problem is a temporary shut down of compressor when more power is required as everybody mentioned. Regarding thermostat, YES its there in modern cars also, but does a different job of cutting off compressor to prevent ice build up. It has NOTHING to do with the temperature setting knob. The BLUE-RED knob will simply mix hot and cold air. Regarding 1.4 Figo owners, they wont be able to notice this lag much, thanks to the torque of a diesel I've heard comments from petrol Figo owners regarding power loss with a/c. The culprit is larger compressor coupled with a relatively lower power engine. Regarding the same issue in Alto, I think the issue will be resolved with the introduction of K10 Alto.
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Old 13th August 2010, 07:41   #27
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Originally Posted by Gansan View Post
Hey, Figo owners are now usurping the copyrighted story of Alto owners!
@Gansan, that remark was truly hilarious

To help in this "Quick overtaking maneuvre by switching Off and On of the AC", the Figo and Alto cars must provide the AC ON / OFF switch on the steering wheel itself, I think.
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Old 13th August 2010, 07:42   #28
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The drag on the engine depends upon the power of the compressor and not on the temperature setting. If Ford has put a large compressor there is no way you can improve matters EXCEPT by switching off AC when you need to climb or overtake. I do this regularly with my Alto. At cruising speeds I do not find the AC to pose any problem. On the lighter side: after hearing about your Figo grouse, I am more in love with my Alto.

The thermostat control simply changes the DUTY-CYCLE of the compressor and not the power of the compressor. Duty cycle means ratio of on to off time of the compressor.

Will somebody please throw light on this? How is the compressor r.p.m regulated when the engine runs at different revolutions? Or is this regulation not required?
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Old 13th August 2010, 11:11   #29
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Originally Posted by Gansan View Post
In the case of Alto, this is caused by mating the larger Wagon-R AC to the 800 cc engine.
I don't think the wagonR runs the same compressor. Alto's comp is the second highest in CC after Baleno's in the Maruti stable.

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Originally Posted by DCEite View Post
Is it advisable to switch on/off ac while the car is in motion ?
Why not ! Ensuring a minute's gap before switching it back on will be better though.
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Old 13th August 2010, 11:42   #30
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Hey guys,

I have a Swift 1.3 and have no issues with loss of power with th AC switched on. I have however noticed that this usually happens when the engine is out of tune. This is noticed when the AC compressor cuts in and the car jerks and loss of power is well felt. This is eliminated when the engine is in tune.

Also, one must switch on the AC only after the engine is warm. Avoid switching on the AC after a cold start. I guess this applies to older non-MPFI cars but it works pretty well for me too.
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