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Old 30th November 2011, 15:38   #46
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Default Re: Air-con compressor in a diesel car does not trip?

Your first post was not clear, hence the query. I am not asking you because I do not know, I just want to understand what your are implying which was not clear to me in your previous post.

BTW, what is decided first the greenhouse or the HVAC sub-systems?

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Old 30th November 2011, 17:33   #47
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Default Re: Air-con compressor in a diesel car does not trip?

Quote:
Originally Posted by thoma View Post
My very next few sentences of the post should have cleared your doubt on why.

By low efficiency, I am really not meaning poor efficiency of the A/C as such. An automobile A/C is designed keeping in mind the space it is required to cool too.

Imagine a very high capacity A/C in a small car which can freeze the cabin in a couple of minutes. Here the A/C is highly efficient. The other way round, imagine fitting a car A/C to a Volvo bus. You can term this A/C as inefficient. The speed of the compressor motor, the refrigerant used, space to be cooled all lead to making the A/C efficient or not.
I think that you meant capacity, rather than efficiency. Both are rather distinct in their meaning

- Efficiency (in case of AC) is the ratio of input power to heat removal, that is if efficiency is low more input power is required to remove "X" amount of heat while higher efficiency would mean less power is required for same heat removal.

- Capacity (in case of AC) is the rate at which heat can be removed. Higher capacity means more heat can be removed, while low capacity means less heat can be removed.
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Old 30th November 2011, 18:49   #48
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Default Re: Air-con compressor in a diesel car does not trip?

Quote:
Originally Posted by Aroy View Post
I think that you meant capacity, rather than efficiency. Both are rather distinct in their meaning

- Efficiency (in case of AC) is the ratio of input power to heat removal, that is if efficiency is low more input power is required to remove "X" amount of heat while higher efficiency would mean less power is required for same heat removal.

- Capacity (in case of AC) is the rate at which heat can be removed. Higher capacity means more heat can be removed, while low capacity means less heat can be removed.
Did I sound too confusing? If efficiency is what is defined as above, I think I wanted to tell about efficiency itself. For a lesser efficient A/C, the compressor motor should over work (in terms of time) to reach the desired / set temperature.
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Old 30th November 2011, 19:00   #49
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Default Re: Air-con compressor in a diesel car does not trip?

After going through this thread and

http://www.team-bhp.com/forum/techni...-fooled-2.html (Airconditioning cars, were we fooled?)

i am now thoroughly confused.

Last edited by enzo10 : 30th November 2011 at 19:01.
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Old 30th November 2011, 23:19   #50
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I felt that the ac of my car was not effective. Hence i went to MASS. The tech came with an electronic thermometer and inserted its needle like sensor in the front vent. He was reving the engine in neutral. Asked him why? He showed me the gauge display where as he revvd the temperature would fall. I placed my palm on the vent and tried it myself. As i pressed the accelerator the more chilling air would come from the vent. He said this is how it is in DDIS. He said this is the reason when driving faster on highway the interior cools faster. Glad that there was no issue. It was just due to the hot weather during the summer that the cooling felt a bit less.

Last edited by tush : 30th November 2011 at 23:30.
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Old 30th November 2011, 23:40   #51
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Default Re: Air-con compressor in a diesel car does not trip?

Quote:
Originally Posted by tush View Post
I felt that the ac of my car was not effective. Hence i went to MASS. The tech came with an electronic thermometer and inserted its needle like sensor in the front vent. He was reving the engine in neutral. Asked him why? He showed me the gauge display where as he revvd the temperature would fall. I placed my palm on the vent and tried it myself. As i pressed the accelerator the more chilling air would come from the vent. He said this is how it is in DDIS. He said this is the reason when driving faster on highway the interior cools faster. Glad that there was no issue. It was just due to the hot weather during the summer that the cooling felt a bit less.
You can probably buy that thermometer and test it yourself,it costs 400 bucks.i have one,and rather than revving while being in neutral,its better that you drive around,with the needle inserted in the vent,normal grill temperature should be around 5-8 degree celcius.
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Old 1st December 2011, 00:01   #52
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Quote:
Originally Posted by akshay4587
You can probably buy that thermometer and test it yourself,it costs 400 bucks.i have one,and rather than revving while being in neutral,its better that you drive around,with the needle inserted in the vent,normal grill temperature should be around 5-8 degree celcius.
Yeah thanks for the advice. Revving in neutral is not good. But i remember, this was 3 years back and MASS tech did it with a light foot and just for 2-4 minutes and in gaps. Sure, buying one would be good if i need to check again. :-)

Last edited by tush : 1st December 2011 at 00:02.
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Old 1st December 2011, 00:48   #53
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Default Re: Air-con compressor in a diesel car does not trip?

Quote:
Originally Posted by akshay4587 View Post
You can probably buy that thermometer and test it yourself,it costs 400 bucks.i have one,and rather than revving while being in neutral,its better that you drive around,with the needle inserted in the vent,normal grill temperature should be around 5-8 degree celcius.
Hey akshay,

Is it called/known by some unique name? Because I did try finding one for myself & couldn't even make most shopkeepers understand.
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Old 1st December 2011, 01:49   #54
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Default Re: Air-con compressor in a diesel car does not trip?

Quote:
Originally Posted by blackfire_9 View Post
Hey akshay,

Is it called/known by some unique name? Because I did try finding one for myself & couldn't even make most shopkeepers understand.
I purchased it as a digital thermometer,it is available at shops dealing with all kinds of electronics goods.
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Old 1st December 2011, 02:14   #55
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Default Re: Air-con compressor in a diesel car does not trip?

Oh ok, because I thought it is some unique type whose sensors can be inserted/placed inside the air vents; basically, a thermometer designed specifically for measuring grill temperatures on an automobile

Thanks for the tip mate, take care.
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Old 1st December 2011, 10:47   #56
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Default Re: Air-con compressor in a diesel car does not trip?

The compressor in Ritz - Diesel is of Variable Displacement type, hence may not trip.

Most of the other petrol vehicles have Fixed displacement in either piston or scroll type technology. Hence they trip once the desired cooling is achieved.

In Variable displacement type compressor the pumping capacity of the compressor can be varied from 6% to 100%, depending upon the load on the AC unit.
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Old 1st December 2011, 12:08   #57
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Default Re: Air-con compressor in a diesel car does not trip?

Quote:
Originally Posted by thoma View Post
Did I sound too confusing? If efficiency is what is defined as above, I think I wanted to tell about efficiency itself. For a lesser efficient A/C, the compressor motor should over work (in terms of time) to reach the desired / set temperature.
It is not efficiency it is effectiveness which further boils down to capacity as already rightly pointed out.
Efficiency : Air conditioner efficiency express the ratio between heat removed to watt of power used. Source http://www.engineeringtoolbox.com/ai...ncy-d_442.html
An AC can be efficient without being effective when it is under capacity.
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Old 1st December 2011, 12:15   #58
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Default Re: Air-con compressor in a diesel car does not trip?

Quote:
Originally Posted by Sss View Post
The compressor in Ritz - Diesel is of Variable Displacement type, hence may not trip.

Most of the other petrol vehicles have Fixed displacement in either piston or scroll type technology. Hence they trip once the desired cooling is achieved.

In Variable displacement type compressor the pumping capacity of the compressor can be varied from 6% to 100%, depending upon the load on the AC unit.
Why is the variable displacement compressor not provided in petrol cars?
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Old 1st December 2011, 13:09   #59
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Default Re: Air-con compressor in a diesel car does not trip?

Quote:
Originally Posted by Sss View Post
The compressor in Ritz - Diesel is of Variable Displacement type, hence may not trip.

Most of the other petrol vehicles have Fixed displacement in either piston or scroll type technology. Hence they trip once the desired cooling is achieved.

In Variable displacement type compressor the pumping capacity of the compressor can be varied from 6% to 100%, depending upon the load on the AC unit.

Thanks, So what is the effect on engine / compressor's life / FE if the compressor pumping capacity is on 6% after achieving the desired temp, will the FE improve ? Also is it fine to leave it in always on condition if this is the story behind it ?
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Old 1st December 2011, 13:14   #60
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Default Re: Air-con compressor in a diesel car does not trip?

AC compressor on diesels do cut off when the set temperature is reached.

the cooling is checked by inserting the probe in the ac vent and racing the car to 2000 rpm.

the grill temp should be around 3-6 degrees @ 2000 rpm within few minutes.
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