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Thread: AC evaporator set points

  1. #1
    Join Date
    Jun 2019
    Location
    New Port Richey, Florida,
    Posts
    1
    My Cars
    2015 328i

    AC evaporator set points

    On a recent drive my AC all of a sudden starting to blow hot air and the oil temp start going going up quickly.

    I pulled over and shut the car down and let it cool off for a little while.

    I took the car in to BMW for service, and the tech told me that the evaporator needed to be "programmed to raise the minimum temperature for the evaporator". $325.00 please.

    My question is: is there a minimum programmable set point for the evaporator?

    I know what a evaporator is, but but I didn't think it was programmable. I feel that this is a bogus service. The tech did not check the AC pressures. I am wondering why all of a sudden why the AC starting blowing hot air.

    Any thoughts?

  2. #2
    Join Date
    May 2019
    Location
    Singapore
    Posts
    1
    My Cars
    2016 BMW 435i Gran Coupe
    Hi, check your radiator/cooling system.

    Once had this issue appear on my previous car because a pebble had struck my radiator and the coolant was leaking. This would explain why engine temperature is also rising suddenly.

    Another possibility is the air-con compressor has failed, which means the refrigerant is not circulating amd therefore the a/c isn't cold. However this usually doesn't affect engine temperature.

  3. #3
    Join Date
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    The technician you spoke with is absolutely correct. The AC evaporator can freeze up on a long drive, and will stop blowing cold air. There is a programming conversion to raise the minimum evap temp. The IHKA (AC control unit) will cycle the compressor on and off depending on the evaporator temperature. Raising it keeps it one or two degrees higher, thus preventing the freezing. You will never notice the difference, except that it will stay cool for as long as you drive the car.
    ASE and BMW Master Certified Technician

  4. #4
    Join Date
    Aug 2007
    Location
    DE, USA
    Posts
    1,044
    My Cars
    '15 435i,'10 535i,'08 X5
    A frozen evaporator will not only stop blowing cold air, it will reduce air flow to almost zero. If the air volume was normal when temps rose, then your evaporator wasn't frozen.
    If evaporator was indeed frozen, the AC should work normally after sitting over night and thawing....at least until it refreezes.
    Hard to believe the frozen evaporator would cause oil temp to rise though.
    I suggest you make sure your electric fan is working.

  5. #5
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    The tech is right about the programming and raising the minimum temp to prevent a freezing condition.

    Whether or not that's what the original poster was experiencing is a different story.

    Sent from my Pixel XL using Tapatalk
    ASE and BMW Master Certified Technician

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