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Old 29th November 2011, 16:29   #16
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Default Re: Air condition in a diesel Car does not trip

Whether compressor is switched ON/OFF automatically is purely dependent on whether the car is equipped with automatic climat control or not, isn't it?

How is this concerned with fuel type - petrol or diesel?

I think the compressor in my Laura TSi remains always ON irrespective of fan speed - unless I switch it off (using the A/C button) - same with my Hyundai Tucson and I think the same was with my NHC. All these 3 cars do not have automatic climat control.
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Old 29th November 2011, 17:00   #17
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Default Re: Air condition in a diesel Car does not trip

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Originally Posted by anandpadhye View Post
Whether compressor is switched ON/OFF automatically is purely dependent on whether the car is equipped with automatic climat control or not, isn't it?

How is this concerned with fuel type - petrol or diesel?

I think the compressor in my Laura TSi remains always ON irrespective of fan speed - unless I switch it off (using the A/C button) - same with my Hyundai Tucson and I think the same was with my NHC. All these 3 cars do not have automatic climat control.
Yes and No.

As there also are cars like the TATA Safari and many others without ACC which have the compressor switching on and off when the desired Temperature - that is set manually without the automatic control - is reached. It is actually very audible in the Safari as the moment it cuts in the revs of the engine are increased to match the increased load.

The Laura 1.9 PD L&K with ACC of course switches on and off as required.

Last edited by ACM : 29th November 2011 at 17:24.
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Old 29th November 2011, 17:09   #18
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Default Re: Air condition in a diesel Car does not trip

I thought my old Zen (1999) used to switch on and off. Only now I am hearing that most cars do not switch it off.
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Old 29th November 2011, 17:11   #19
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Default Re: Air condition in a diesel Car does not trip

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Originally Posted by anandpadhye View Post
Whether compressor is switched ON/OFF automatically is purely dependent on whether the car is equipped with automatic climat control or not, isn't it?

How is this concerned with fuel type - petrol or diesel?

It concerns the fuel type as Ritz Petrol without ACC has a thermostat but Ritz DDiS does not have a thermostat.
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Old 29th November 2011, 17:15   #20
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Default Re: Air condition in a diesel Car does not trip

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Originally Posted by libranof1987 View Post
But the thing is - when you have the A/c compressor running all the time, it just keeps getting cooler in the cabin which could/would lead many to actually switch the A/c off - effectively having the same end-result, if not worse, that the auto cut-off compressor has.

Also, given the wear and tear part - A/c units with the ACC feature should wear out much earlier than those without, right?
Yes to both.

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Originally Posted by Figopian View Post
If you stand outside the vehicle with A/C switched on, you could hear one hissing sound, I am assuming that is A/C compressor sound and it does go away for a while intermittently, that is the reason for me to consider that the A/C compressor goes on/Off in my diesel Figo. Could it be the evaporator/radiator fan? I don't know, if that fan will make this kind of hissing noise.

Also, I don't get why this facility would be there for petrol engines and not for diesels? Interesting to know though!
Hissing sound is misleading since it happens only at start of AC, usually dies down once its running for a few secs. Better indicator is to watch the engine RPM, if its lowering down as AC cuts off.

Quote:
Originally Posted by anandpadhye View Post
Whether compressor is switched ON/OFF automatically is purely dependent on whether the car is equipped with automatic climat control or not, isn't it?

How is this concerned with fuel type - petrol or diesel?

I think the compressor in my Laura TSi remains always ON irrespective of fan speed - unless I switch it off (using the A/C button) - same with my Hyundai Tucson and I think the same was with my NHC. All these 3 cars do not have automatic climat control.
This part is where i have my doubts, coz i have seen diesel engines with AC cut off even without any automatic climate settings.

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Originally Posted by ACM View Post
Yes and No.

As there also are cars like the TATA Safari and many others without ACC which have the compressor switching on and off when the desired Temperature that is set manually without the automatic control is reached. It is actually very audible in the Safari as the moment it cuts in the revs of the engine are increased to match the increased load.

The Laura 1.9 PD L&K with ACC of course switches on and off as required.
Yup this is what i meant by the above replies
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Old 29th November 2011, 17:17   #21
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Default Re: Air condition in a diesel Car does not trip

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Originally Posted by ACM View Post
Yes and No.

As there also are cars like the TATA Safari and many others without ACC which have the compressor switching on and off when the desired Temperature that is set manually without the automatic control is reached. It is actually very audible in the Safari as the moment it cuts in the revs of the engine are increased to match the increased load.
OK, so a very crude implementation of climat control, OK. So what do they call it in user manual - just curious?

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Originally Posted by TaurusAl View Post
It concerns the fuel type as Ritz Petrol without ACC has a thermostat but Ritz DDiS does not have a thermostat.
Ah - so it's all about whether the cars has a thermostat or not - this has nothing to do with fuel type, isn't it? So The user manual mentions this at all or no (whether the car is equipped with a thermostat or not)?
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Old 29th November 2011, 19:12   #22
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Default Re: Air condition in a diesel Car does not trip

Don't know much about diesels but A/C cuts off in all my petrol cars including Honda City, WagonR and i10.

Could not understand why this feature is not available in diesel especially swift.

I also recall that when I traveled to Chandigarh couple of years back in a TATA Indica, its compressor was also running continuously and cabin was too chilly and we had to switch off the A/C.
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Old 29th November 2011, 19:31   #23
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Default Re: Air condition in a diesel Car does not trip

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Originally Posted by Jaggu View Post
YWhen you switch ON the AC the ECM changes the fuelling in DDiS and compensate for the power loss, also at idle you will see compensation of about 500 rpm.
You meant 100 rpm or 50 rpm right? I only see the rpm moving from 800 to 850/900 when the ac is switched on.
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Old 29th November 2011, 19:45   #24
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Default Re: Air condition in a diesel Car does not trip

Whether the compressor will switch on/off or not depends on its having a thermostat switch. My M800 with third party AC did not, while my next M800 with factory fitted AC had.

Either MUL deliberately left the thermostat out in their diesel cars, or they are just not functioning. Either way it is strange as other diesels have the thermostat. I do not buy the line that the thermostat will interfere with ECU, as their diesel cars run fine with or without the AC. All that you are doing with a thermostat is simulating pushing the AC knob on and off.

A thermostat has nothing to do with ACC, it is there just to maintain temperature.
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Old 29th November 2011, 19:55   #25
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Default Re: Air condition in a diesel Car does not trip

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Originally Posted by Aroy View Post
A thermostat has nothing to do with ACC, it is there just to maintain temperature.
Not "maintain" in the true sense of the term actually. It just constantly provides temp. at the desired "cool/hot" level.

It doesn't maintain the temp. of the cabin.
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Old 29th November 2011, 21:43   #26
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Default Re: Air condition in a diesel Car does not trip

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Originally Posted by TaurusAl View Post
Ok, so now we have reached a conclusion that the A/C does not get cut-off in Diesels, when i asked the same to the service guy of Maruti, he said something like 'The Pump will work less if your keep your blower low'.

I really did not understand what he said. Can anyone put a light on this ? If there is any point in keeping the blower low in a diesel car, and will it save anything at all ?
The AC compressor does cut off in diesels and petrol. It does in my Cruze and my Junkindica. It does in my Vista and Palio GTX too. All this after it reaches a preset grill temperature of 3 degrees centigrade in the GTX and about 7 to 8 degrees in my other cars.

There are variable capacity compressors but they are stupendously expensive to be worthwhile. Please google for variable capacity automobile AC compressors. The old FORD escort had a continuous on compressor and temperature was regulated by mixing cold air with hot air from the engine coolant grill. I doubt that this technique is employed in our mileage conscious Maruti but will be news to me if it does.
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Old 29th November 2011, 21:57   #27
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Default Re: Air condition in a diesel Car does not trip

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Originally Posted by bluevolt View Post
Don't know much about diesels but A/C cuts off in all my petrol cars including Honda City, WagonR and i10.
Are you sure about the A/C cutting off in the i10? When we did the Goa-Mysore-Coorg-Goa trip in our i10 recently, I had used the AC continuously on with the fan on 1 position. After some time, the cabin would get cold and were were left with two options -- either to switch off the AC or to decrease the thermostat (turn the knob away from the maximum 'blue' position and somewhere in between the 'blue' and 'red' -- 9 o'clock position).
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Old 29th November 2011, 22:08   #28
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Default Re: Air condition in a diesel Car does not trip

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Originally Posted by Jaggu View Post
Yes DDiS does not have compressor cut off based on temperature. It just stays ON all the while. I feel this is to avoid the jerks when a compressor kicks in and out. When you switch ON the AC the ECM changes the fuelling in DDiS and compensate for the power loss, also at idle you will see compensation of about 500 rpm.

Long back i had checked with one of the service advisers and they also did not have anymore info than this.
Quote:
Originally Posted by TaurusAl View Post
Ok, so now we have reached a conclusion that the A/C does not get cut-off in Diesels, when i asked the same to the service guy of Maruti, he said something like 'The Pump will work less if your keep your blower low'.

I really did not understand what he said. Can anyone put a light on this ? If there is any point in keeping the blower low in a diesel car, and will it save anything at all ?
No this is not true. I do not think all diesels are void of this compressor control.
I can vouch for Figo diesel because I have experienced the cutoff of the compressor on long drives where you experience a small shake and then after some time it comes back again. Smooth roads, zero traffic is required to notice this.
My friend who drove my figo came back asking what it was because the vibration is certainly distinctive than what happens in a petrol car that he drives.
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Old 29th November 2011, 22:17   #29
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Default Re: Air condition in a diesel Car does not trip

In the Swift Diesel, when you jam the accelerator down the compressor cuts off. Just to see this phenomenon in action, rev the car with the AC on in neutral, when you leave the accelerator, the AC will be off, I ll go to the idle rpm (800 rpm) which is minus the AC rpm and then suddenly after a second the compressor will start again. This is to I guess provide the entire engine power for momentum when it senses the user want's absolute power.

yes otherwise in traffic situation's, i ve never seen the compressor cut off in my Swift D !
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Old 29th November 2011, 22:30   #30
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Default Re: Air condition in a diesel Car does not trip

Is it that the min temp on the temp control is so low that when the temp knob is kept at max blue, the thermostat doesnt cut off? Has anyone tried it with the knob at minimum blue, i mean minimum cold?

Last edited by Abes : 29th November 2011 at 22:31.
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