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Old 4th September 2009, 19:58   #1
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Lightbulb AC Switch OFF or Blower Switch OFF

Team,

I have this very strange habit of switching off the AC via the AC switch when the Cabin gets too Cold and then switching on again when the temperature gets warmer , I was recently told by a keen observer that this is not a good practise and need to switch off the Blower instead of the AC switch as this also results in very less mileage to the litre.

Could you shed some light on this as to whats best practise and as to whether this behaviour brings down the Mileage as well?

1. Switching off the AC switch alltogether or
2. Switching of the Blower whilst keeping the AC switch on.

Cheers

Peter.
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Old 4th September 2009, 20:03   #2
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Peter - I'm not sure if it makes any difference but Thank God your not driving an Alto, in the city the car would jump at the press of the pedal once you switch off the AC.

I guess it makes a difference on the Average as you keep the AC condenser of whatever to go warm and then cool it again hence consuming more fuel. Why dont you adjust the temperature to keep something which you are comfortable in?

Last edited by CorsaLove : 4th September 2009 at 20:06. Reason: missed a line.
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Old 4th September 2009, 20:07   #3
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What is your car? I switch off the A/C and leave the blower on while going up steep inclines with a full load in my Alto. I will switch it on after coming down. It makes no difference as to what switch you use, not straining the engine too much is more important IMO. I will rather replace a switch periodically if necessary!
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Old 4th September 2009, 22:47   #4
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What actually happens when somebody switches off the blower while the AC is running? Do the compressor still runs or it switches off?
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Old 4th September 2009, 22:50   #5
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Quote:
Originally Posted by CorsaLove View Post
Peter - I'm not sure if it makes any difference but Thank God your not driving an Alto, in the city the car would jump at the press of the pedal once you switch off the AC.
That's the Alto's nitro boost button. You get instant boost and can really judge your overtaking if you master that button.

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What actually happens when somebody switches off the blower while the AC is running? Do the compressor still runs or it switches off?
Both switch off, compressor and blower.
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Old 4th September 2009, 23:07   #6
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Quote:
Originally Posted by vid6639 View Post
That's the Alto's nitro boost button. You get instant boost and can really judge your overtaking if you master that button.
We call it NOS button. Whenever i have to overtake in a hurry i say to the co-passenger to press the NOS button

P.S. If you want to experience what nitrous boost feel like just drive an Alto with AC on and turn off the AC when u have to overtake. Thats the closest you can get without installed NOS.
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Old 5th September 2009, 00:01   #7
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The best way of keeping the cabin comfortable is to set the thermostat (temprature knob/slider) to a comfortable position instead of switching on and off. You can make adjustments via the temp. control alone.

In the cars I have owned, the blower continues to work even when set to '0' if the A/c. button is on. The only way of switching the blower off is to switch off the a/c. switch and then move the blower switch to '0'. If the blower is off when the a/c. compressor is running - there will be ice formation on the a/c. coils.

cheers,
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Old 5th September 2009, 00:05   #8
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When there's no power to Blower, there's no power to Compressor,
If you turn off blower, it will also cut the power to compressor atleast in Santro.
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Old 5th September 2009, 00:43   #9
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Quote:
Originally Posted by Peter View Post
Team,

I have this very strange habit of switching off the AC via the AC switch when the Cabin gets too Cold and then switching on again when the temperature gets warmer , I was recently told by a keen observer that this is not a good practise and need to switch off the Blower instead of the AC switch as this also results in very less mileage to the litre.

Could you shed some light on this as to whats best practise and as to whether this behaviour brings down the Mileage as well?

1. Switching off the AC switch alltogether or
2. Switching of the Blower whilst keeping the AC switch on.

Cheers

Peter.
Best practice>
Once you have achieved the required cooling in your car, you can set the thermostate or the temperature knob (the one with the blue and red markings) at a desired temperature. this will ensure that while both the AC and Blower motor are running, the compressor will shut off when the desired temperature is achieved.

this method will get you some better FE.

correct way to switch ON the AC unit is like this>
1. switch on the blower motor
2. set the temperature at desired settings
3. keep the air flow settings on re-circulation
4. switch on the AC.

correct way to switch OFF the AC unit is like this>
1. switch OFF the AC switch.
2. let the blower motor run for 2-3 minutes without the AC
3. switch OFF the blower motor.

i would like to advice that if you switch OFF the AC switch around 1km from your destination and keep the blower motor running, this method will ensure that the condensor/evaporator/cooling coils will not be left damp and cold (which helps bacteria breeding) and results in BAD odour/smell from your AC.

keeping the blower motor running after switching off AC will ensure that the condensor/evaporator/cooling coils will be dry by the time you reach your destination.

switching OFF blower motor without switching OFF the AC is not the correct way!
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Old 5th September 2009, 01:08   #10
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I am sure no one has tried it in the OLD 800 it is a real big NOS in it... when we watched the Fast and furious for the first time at that time we started imitating this thing... hehehe its funn still do it even on my zen i get the boost
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Old 5th September 2009, 05:32   #11
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Quote:
Originally Posted by desideep View Post
I am sure no one has tried it in the OLD 800 it is a real big NOS in it... when we watched the Fast and furious for the first time at that time we started imitating this thing... hehehe its funn still do it even on my zen i get the boost
I had been running my Maruthi-900 like that. My wife rides shot gun and doubles as the A/C controller for hill climbing, overtaking etc leaving me the job of driving the car without bothering acceleration, pickup etc. ( As per the A/C mechanics the Temp Control knob in the 800 is a dummy & temperature control is acheived by the thermostatic bypass valve operating at 5*C at the evoporator). Have to confirm this.

Switching off the A/C only switches off the compressor and keeps the blower running and hence keeps air circulating in the cabin, but switching off the Blower switches off the compressor, Radiator fan and the A/C blower, may save lots of fuel.

Last edited by sudharma : 5th September 2009 at 05:37. Reason: Add more Info.
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Old 5th September 2009, 07:37   #12
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@OP: What you are doing is okay and no need to change your habit. Switching the compressor on or off as per need is better practice and returns better fuel economy. The blower motor does not take that much power comparatively and circulating air keeps you fresh.
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Old 5th September 2009, 07:48   #13
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Quote:
Originally Posted by Parm View Post
correct way to switch OFF the AC unit is like this>
1. switch OFF the AC switch.
2. let the blower motor run for 2-3 minutes without the AC
3. switch OFF the blower motor.
Quote:
i would like to advice that if you switch OFF the AC switch around 1km from your destination and keep the blower motor running, this method will ensure that the condensor/evaporator/cooling coils will not be left damp and cold (which helps bacteria breeding) and results in BAD odour/smell from your AC.

keeping the blower motor running after switching off AC will ensure that the condensor/evaporator/cooling coils will be dry by the time you reach your destination.

switching OFF blower motor without switching OFF the AC is not the correct way!
I practice the quoted all the way. I agree with the bad odour thing.

Quote:
Originally Posted by desideep View Post
I am sure no one has tried it in the OLD 800 it is a real big NOS in it... when we watched the Fast and furious for the first time at that time we started imitating this thing... hehehe its funn still do it even on my zen i get the boost
Exactly, guys were talking about the M800 and the Alto, Zen is no better. It also has a NOS Cylinder as an AC condenser
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Old 5th September 2009, 08:42   #14
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I think ac switches off automatically when you switch the blower off. Although you dont need to switch off the ac as the compressor cuts off when temperature reaches to desired level , but if you feel cold than you can switch off the ac manually and keep the blower running . You can again switch on the ac when cabin temperature increases. But i would not advise you to do it repeatedly in short intervals as this may damage components.
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Old 5th September 2009, 08:51   #15
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IMHO, compressor is quite a load on the engine and Switching ON and OFF will increase FE. Its almost impossible to avoid the Switching ON and OFF procedure.

Try to use the AC like this :
When two humans beings in the car, keep the blower position on 1 or 2 fan speed.
When more than 2 humans in the car, keep the blower position above 2 initially, but after the cabin has cooled down to desired level, decrease the blower speed.

This way you are not switching off compressor or blower, but you are putting less wear and tear on parts like compressor clutch.

When it becomes too cool, switch of compressor for one minute or so. This also prevents something called Icing. I dont know about latest systems, but in earlier systems icing was a problem.
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