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Erratic AC, fogging windows, and persistent wiper issues

Discussion in 'Model S' started by Racerx22b, Sep 29, 2015.

  1. Racerx22b

    Racerx22b Member

    Nov 17, 2014
    West Palm Beach, FL
    As noted in the title I am experiencing some unusual AC behavior and really annoying wiper issues. See explanation below.

    Issue #1:
    The AC blower motor fluctuates it’s fan speed all on it’s own. The AC is set to a fixed fan speed (AUTO is off) and at any fan speed you set it at it just raises and lowers the speed of the blower at random. See video link below. You can hear the noise of the blowing air fluctuate. That is not a result of a trick I am performing with the positioning of the microphone. Click here. Around 22sec in you’ll hear it slow down then right towards the end you’ll hear it speed up. You’ll need to really crank up your computer speakers to hear it but in the car it’s crystal clear and you can feel the air speed go up and down. Thoughts?

    Issue #2:
    Front window fogs over when using AC in the rain. See attached pics. AC settings are same as seen in the video demonstrating the erratic blower speed (Defrost is not selected). The longer it rains the more fogged over the window gets. At some point you are forced to turn on defrost with heat just to see where you are going. Just imagine how pleasurable this is when it’s 90 degrees outside and how embarrassing it is when you have guests in your $100k car.

    Issue #3:
    Chattering wipers and audible clicking noise from wiper motor. Our car has already been serviced for this once. I believe they stated all was working as it should but they replaced the wipers and they felt it was resolved. Once we drove through our first rain storm the problem returned. Since then, I have tried Rain X blades that resolved the issue for about 2-3 storms and then it returned. I then replaced the blades with the Bosch ICON blades that people on this forum claim resolves the issue. It only worked again very briefly. The links below demonstrate the issue. Yes, the window is basically dry but I haven’t figured out how to video it while driving in the rain. Trust me, it behaves in the same manner no matter how wet or dry the window is. Although it seems petty to make such an issue of this I challenge you to drive 20 minutes in a driving rain storm with the wipers squeaking and chattering as seen in this video without shaking your head in frustration. Concern #2 is with the excessive noise coming from the wiper motor. The clunking and clicking don’t seem like something that should be present from the factory if all was within working spec. Click here for the view from the inside and here from the view from the outside. You can actually see the window fogging issue a little in the video from the inside

    Anyone else experience this? If so, was Tesla able to resolve it?

    IMG_0688.png IMG_0695.png
  2. scot

    scot Member

    Jul 11, 2015
    It looks like the fog is on the inside, correct?

    I believe the fan in the car is an ECM blower, similar to the higher end furnaces. If so, the fan has multiple CFM speeds and while you might have a fixed speed, it doesn't actually know what that means. It actually tries to have a fixed output, which may require the blower to spin faster or slower to match. It also turns on/off the recirc functions (if you have it set to auto) which can make it seem like the fan increases or decreases because it will take more pressure to actually keep a similar CFM/airflow.

    The fog could be due to low airflow or improperly filled AC system. It could be too cold coming from the vents, which can cause condensation in the car. It might clear up as water is removed from the air, but hard to say.

    Look for obstructions to airflow for the HVAC and make sure all of your vents in the car are open. If the filters or intake are blocked (leaves, dirt and the like) it could cause all of these symptoms.

    If nothing obvious comes up I'd suggest getting it checked out.

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