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Thread: Help! Strange AC symptoms

  1. #1
    Join Date
    Feb 2015
    Location
    United States
    Posts
    3
    My Cars
    2002 330i

    Help! Strange AC symptoms

    Thank you in advance!

    I have a 2002 330i. Love this vehicle! Just finished replacing the thermostat and lower radiator hose along with a fresh oil change and it drove fine, all is normal, AC working great and keeping me cool as the temperature is creeping up to 90. All of a sudden the cool air turns warm. The strange thing is that when I turn off the auto function and press the up, right, and down vent buttons cool air will blow out of the vents. If I go back and press the auto button the air turns warm. Any advice identifying the problem is greatly appreciated!

  2. #2
    Join Date
    Feb 2015
    Location
    United States
    Posts
    3
    My Cars
    2002 330i
    Update
    When I turn off the up vent button there continues to be cold and the air coming out of the driver side vent becomes colder. If I turn off the down facing vent button air becomes warm again. So I am currently getting cold air by having the right and downward vent buttons lit up. The foot vent is blowing out hot air however.

  3. #3
    Join Date
    Jul 2011
    Location
    Arlington, VA
    Posts
    9,931
    My Cars
    2018 BMW M240i
    Is the dial between the 2 center vent showing blue dots? Are you having any electronic or electrical issues? Does the external ambient air temperature readout in the dash show the proper temperature consistently? Does the compressor clutch disengage when you loose ac with automatic climate control module (IHKA in BMWspeak) is in auto? Is the cold air coming from the dash vents on the passenger side the same temperature as the cold air coming from the vents on the driver’s side? If there’s a difference the refrigerant level is low.

    The ac is controlled by the automatic climate control module. It receives inputs from various sources:
    - engine computer (DME)
    - external ambient air temperature sensor
    - evaporator temperature sensor
    - refrigerant pressure sensor
    If any of these inputs is missing the ac will not work.

    Additionally, the IHKA may be going bad. However, it’s a very reliable module so I think something else is wrong.

  4. #4
    Join Date
    Feb 2015
    Location
    United States
    Posts
    3
    My Cars
    2002 330i
    The middle dial is all the way in the blue. No other electronic or engine issues. No faults or pending faults. External temp sensor operating normally. I will check on the compressor clutch and air vent temp when I am back from work tonight!

    I greatly appreciate the help!!!

  5. #5
    Join Date
    Apr 2015
    Location
    Netherlands
    Posts
    164
    My Cars
    2000 E46 328i
    So this may sound silly.. But do you have a phone holder that covers one of the top air vents?

    I recently diagnosed a problem exactly like this in a 330i, where the cold air from the air vents was blowing against the owner's phone and phone holder which redirected the cold air right onto the temperature sensor in the climate control panel (the little grid to the left of the temperature display has the sensor). Closing the covered air vent fixed the problem

  6. #6
    Join Date
    Jul 2011
    Location
    Arlington, VA
    Posts
    9,931
    My Cars
    2018 BMW M240i
    Quote Originally Posted by Raddee View Post
    So this may sound silly.. But do you have a phone holder that covers one of the top air vents?

    I recently diagnosed a problem exactly like this in a 330i, where the cold air from the air vents was blowing against the owner's phone and phone holder which redirected the cold air right onto the temperature sensor in the climate control panel (the little grid to the left of the temperature display has the sensor). Closing the covered air vent fixed the problem
    Wow! Would have never thought of that!!! Great find!

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