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Defrost only, no vents or floor

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Noiseydiesel, May 26, 2020.

  1. Noiseydiesel

    Noiseydiesel Full Access Member

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    '94 7.3 idi turbo F350 crewcab dually.
    Defrost works good hot or cold. I repaired the vac line to the dash and got it working and still no vent switching action. Fan works good, temp change works good also.
    Any ideas?
    Thank you one and all in advance!!
     
  2. Cactus Bob

    Cactus Bob Registered User

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    well you still got a leak ....somewhere. or you have a bad vacuum pump. it can only be one of the two. if your pump works and your sure we move to step two.

    you need a "quiet" vacuum source , you can't use your pump because the engine is too noisy . so what i do it connect a long hose to an(electric operated) AC vacuum pump and put the pump outside my shop. this will gives me a steady vacuum source and a quiet one too.
    Now with this setup you can trace your vacuum leak with your hands and ears. one note: the Ford control panel leaks a little when they get old, this is normal and will not cause a problem.you are looking for a big leak not a little one.
    Take your time and let your ears do the work
     
  3. Noiseydiesel

    Noiseydiesel Full Access Member

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    Thank you one and all for the responses.
    I finally got to the dash panel removal, easy enough, removed the vacuum connector and found no signal. I went back out to the manifold connector and found a very small split on the side of the hose connector at the manifold. I repaired that and got a signal to the dash.
    Naturally, one of the nipples on the switch broke off and I have another one ordered up.
    The wife should be happy to have A/C out of the vents rather than just the defrost...
    God Bless!
     
    chillman88 likes this.

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