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AC compressor

Discussion in 'Electrical Systems' started by r2d2, Aug 2, 2012.

  1. r2d2

    r2d2

    Messages:
    19
    Does the Automatic Climate Control on the Linea cut the compressor of the AC (as with home units) when the required temperature is reached? Does this happen in full auto mode or does it also apply to the auto (normal) mode?


    Thank you all for answering

    Enjoy the summer with a well behaved and easy cooling ACC system of the 2012 Linea
    Last edited: Aug 2, 2012
  2. saroshmk

    saroshmk

    Messages:
    53
    Hyderabad
    I was told that the 2012 models come with a DC inverter that lowers the speed of the compressor rather than cut it off. This is what they did to tropicalise it for India. I own an active variant with manual controls so can't really tell whether this is true.
    Last edited: Aug 3, 2012
  3. PaddleShifter

    PaddleShifter Staff Member Janitor

    Messages:
    2,697
    Chandigarh
    Grande Punto 1.3
    No, the AC compressor does not cut off. Frequent on-off of AC compressor is not good for the car's engine anyways. Home ACs and car ACs work very differently as the space they have to cool is very different.
  4. r2d2

    r2d2

    Messages:
    19
    On "full auto" after reaching the said temperature it feels like its simply blowing air through the hoses that are already cooled. I was looking for somebody with technical knowledge to respond to this one. It is not as if this is a banal discussion, if indeed the compressor is being cut off (fuel economy increases by about 5-10%) in 'Full Auto' mode then one can extract better fuel economy and maybe the compressor will last longer.

    If this is indeed the case, then Fiat can advertise it as a feature just as all other manufacturers advertise every possible non-feature as if it was the first time that the feature was being implemented in cars by mankind. - 12 step AC fan, Automatic Climate Control, Intelligent cut off, More fuel economy in hot India, best in class..., first in class... etc etc

    Fiat gurus enlighten us please. :confused:
  5. karan desai

    karan desai Superiore

    Messages:
    805
    Morbi, Gujrat
    the compressor does turn on and off. inverter acs have the technology where the rpm of the compressor decreases when it reaches the desired temperature (just like driving in the eco mode at say 60-70) but not in our car acs. i can definitely feel a jerk when the compressor turns on or off. so thats for sure. after a certain set temperature what the ac does is it mixes hot air from the radiator to increase the temp above the compressor cut off thing. the funda was very simple in my uno. increase the temp and the comp will stay off for a longer time.
  6. sriramr9

    sriramr9 Amatore

    Messages:
    211
    Chennai
    Is there a method to use the car a/c judiciously and safely at the same time, now what i do is hit the flower icon (air con compressor switch) everytime when i feel the cabin gets chilled up and again turn it on while i start feeling warmer, all when the car is running, every hit for ON or OFF results in the compressor turn on/off cycle happening, is it harmful to the compressor/ engine in anyway such frequent operations, i use the a/c very judiciously and sparingly like only on very hot days or when travelling with family and on few cases run it for short intervals to keep the system in proper working condition. i have never driven the vehicle till date with the a/c on continously,

    please suggest a safe way to use the punto' auto air con system in the interest of maintaining it in condition for a longer period of time and at same time extract the most miles per liter of diesel spent.

    what i do is lower the front right window little bit and rear left window a bit to ease out cross ventilation. is this method, is this practice a good one as the drag will be lesser in this case ?
    Last edited: Nov 27, 2012
  7. Italia-Linea

    Italia-Linea Staff Member Janitor

    Messages:
    2,123
    Pune
    Linea and Punto with auto climate control are fitted with " Variable Displacement Compressors". Its different from manual ac which has " Fixed Displacement Clutch type compressor".

    In clutch type compressor when you switch on the AC the clutch engages and the pistons reciprocate. While idling the efficiency reduces and in high rpms it increases. When you switch off the Ac button the clutch disengages and compressor no more pumps.

    In variable type the computer judges the requirement in the cabin based on various sensors. Accordingly it adjusts the control valve in the compressor which is connected with a rod to a cantilever type plate also called wobble plate. The plate alters the stroke of the piston. So when you require very cold air the piston stroke is increased and it pumps more.

    The benefit of the Variable compressor is that it puts less load on the engine. Also its efficiency is more and so mileage also improves. Its silent and jerk free too.

    I have tried to explain as much as i can in laymans language. I hope its clear.


    Secondly its a myth that shutting AC off again and again increases mileage. Keep it on and it will control cabin temp and alter its operation automatically.

    On non auto AC keep AC blower speed on 1-2 setting and keep the AC running. It will cut off more early in low blower speeds and maintain cabin temp too.
    Last edited: Nov 27, 2012
    6 people like this.
  8. Italia-Linea

    Italia-Linea Staff Member Janitor

    Messages:
    2,123
    Pune
    Also forgot to mention that keeping AC in recirculating mode cools the cabin quickly and also keeps dust away from entering the cooling coils. So full auto mode in climate control mode is not preferrable in india.
  9. punto_emotion

    punto_emotion Esperto

    Messages:
    1,245
    Bangalore
    Grande Punto 1.3
    @ Italia-Linea, great piece of info! Thanks for sharing :clap
    1 person likes this.
  10. sriramr9

    sriramr9 Amatore

    Messages:
    211
    Chennai
    Three weeks ago while driving in mid day, in auto a/c mode, the central air con louvers blew out kind of grey coloured fumes/smoke for about a minute. there was no engine over heat observed, no burning smell from engine bay, nothing, when compressor was turned off the smoke ceased to come,

    i turned off the a/c after that pulled over to the left with parking lights enabled, i opened the bonnet and looked for any suspicious activity happening, none so ever, with engine in idle, i turned on the blower first in full speed for 1 minute followed by hitting the compressor button,

    no more smoke, no fumes, the air blew out was clear, then on i have not experienced anything of that sort till now, Is this a cause of concern. or because of driving in with the auto aircon mode enabled could have caused this ?

    please elucidate italia linea ?
    Last edited: Nov 28, 2012

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