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Air Con only on tickover

Discussion in 'Exeo & Exeo ST' started by caldi, Jul 4, 2019.

  1. caldi

    caldi Active Member

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    My air con works only on tick over, no alarms, econ indicator goes off and stays off but no cooling as the revs rise, what could this be caused by?
     
  2. JR_130

    JR_130 Active Member

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    not too sure, could be difficulty with the clutch on the aircon pump or the pump itself getting to the end of life and becoming too hard to turn?
     
  3. caldi

    caldi Active Member

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    I have done some research, the Exeo does not have a clutch on the pump it is a variable displacement pump which runs all the time. The delivery of the pump is controlled via a PWM signal to an internal solenoid valve which controls the angle of a swash plate. I need to get some checks on the wiring from the PCM to the solenoid. Update, there is a clutch but not a magnetic one, it is a safety clutch which shears if the compressor seizes to protect the belt. My compressor is running and all the readings are correct except the discharge pressure when above 1200 rpm this just drops to 5 Bar, I am going to replace the control solenoid valve on the compressor, cheap enough but means a re-gas after.
     
    #3 caldi, Jul 15, 2019
    Last edited: Aug 10, 2019
  4. caldi

    caldi Active Member

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    Compressor control valve replaced, still no aircon at higher revs, faulty compressor? could be expensive.
     
  5. Pbsky72

    Pbsky72 Active Member

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    Just gonna say .. do what I do.. open the windows.. its cheaper.. not helping in know
     
  6. RUM4MO

    RUM4MO Active Member

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    Have you checked the compressor load wiring that is running to that control valve?

    Edit:- sorry if I have not re-read all the postings, but have you connected monitoring gear to this system, a set of fridge gauges so that you can see how the suction side varies when the discharge side suddenly drops? A mobile proper fridge person could help you a lot I'd think.

    Another Edit:- does the cooling fan switch on at the correct time? Do you now that the pressure sensor is working okay, it might be misreading the rising pressure and protecting the compressor.
     
  7. caldi

    caldi Active Member

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    The signal to the control valve stays high and the compressor state is shown as on
     
    MATT RILEY likes this.
  8. RUM4MO

    RUM4MO Active Member

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    I'd still think that having a look at actual running pressures measured using a fridge manifold, at both monitor points, would help work out what is happening - and comparing the discharge readings with what the pressure sensor is readings are.
     
  9. caldi

    caldi Active Member

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    Even if the sensor readings are correct and sensible? the output pressure goes down the cooling stops, the control is demanding full cool, the current is correct, its a faulty compressor, my next move is to fit a replacement.
     
  10. RUM4MO

    RUM4MO Active Member

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    I was hinting at “what is the low side pressure doing at this time” so evaluate if it was the compressor that was being proved to be the problem, many other bits in there like evap temperature sensor and orifice sieve assembly and drier.
     

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