Climate Control Improvement
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Thread: Climate Control Improvement

  1. #1
    Fellow Frogger! Jinandfonic's Avatar
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    Default Climate Control Improvement

    In my search for more A/C knowledge I found this which would be relevant to any modern HVAC system:
    Modify the A/C to give cooler temperatures
    Basically this UK Ford owner wasn't happy with the speed at which his car cooled the cabin on really hot days and discovered the de-ice thermister is set too high and devised a manual override which has transformed it's cooling performance from adequate to impressive apparently. PSA products are probably use a similar setting (2*c evaporator temp compressor cut out) for their milder European summers & damp winters. Anyone have diagrams of a C4 HVAC system?

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  2. #2
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by Jinandfonic View Post
    In my search for more A/C knowledge I found this which would be relevant to any modern HVAC system:
    Modify the A/C to give cooler temperatures
    Basically this UK Ford owner wasn't happy with the speed at which his car cooled the cabin on really hot days and discovered the de-ice thermister is set too high and devised a manual override which has transformed it's cooling performance from adequate to impressive apparently. PSA products are probably use a similar setting (2*c evaporator temp compressor cut out) for their milder European summers & damp winters. Anyone have diagrams of a C4 HVAC system?
    Your right, I remember the C4 not being great on a hot day. neither is the 407. I'm wondering if they aren't slightly under-charged too. Apparently the later land rovers suffer the same issues and people mess with the thermisters settings. I wonder why they didn't just buy a standard/universal pot/variable resister rather than making there own up like that

    If you can access the thermister, why don't you try moving it slightly out of the evaporator and see if it blows colder If it makes no difference, the A/C is already working at 100% capacity, so there is no point messing with it

    seeya,
    Shane L.
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  3. #3
    1000+ Posts robmac's Avatar
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    Default

    Quote Originally Posted by Jinandfonic View Post
    In my search for more A/C knowledge I found this which would be relevant to any modern HVAC system:
    Modify the A/C to give cooler temperatures
    Basically this UK Ford owner wasn't happy with the speed at which his car cooled the cabin on really hot days and discovered the de-ice thermister is set too high and devised a manual override which has transformed it's cooling performance from adequate to impressive apparently. PSA products are probably use a similar setting (2*c evaporator temp compressor cut out) for their milder European summers & damp winters. Anyone have diagrams of a C4 HVAC system?
    I'd be very careful of this mod for French cars.

    Indeed I'd be careful of treating the modification as "generic".

    It may or may not work dependent on the specification of the evaporator temperature sensing thermistor. It is also dependent on the super heat setting on the TX valve. It may simply cause the evaporator to ice up.

    Definitely do some experimenting before drilling holes or hacking at the wiring. Also the name "de-ice" switch is BS. It is simply a temperature switch that drops the compressor clutch when the set temperature is reached. Called a thermostat in the industry. The de-icing is done by air continuing to flow over the coil.

    BTW many of the thermistor control units (thermostat systems) have a trim pot on the circuit board, sometimes these are only accessible by baring the circuit board. Adjusting the trim pot will achieve the same results as the Ford mod.

    After all, the aim of mod is to adjust the the thermostat to allow the coil to reach a lower temperature before the clutch cuts out.

    EDIT:

    Another possible undesirable side effect is the balance between heat/cool and oration of the blend door may be impacted. The coil will running at lower temperature therefore more heat will be required to balance the temperature.

    Also the compressor will be running longer to make the evap coil cooler - increased fuel consumption.
    Last edited by robmac; 9th December 2014 at 06:14 PM.
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