front windshield defroster blower

Discussion in 'General Ranchero Help' started by Gregory Cummings, Jan 13, 2020.

  1. Gregory Cummings

    Gregory Cummings In Second Gear

    Oceanside, CA
    79 ranchero 351/400M 2v carb.
    1. What the heck when the defogger blows heat but it doesn't defog the front windshield. Heat comes up from the dash defog vents but actually fogs up the window instead of defogging it. Only much later on does the windshield begins to clear from the heat. It seems there's some smoke (but it aint smoke cause it don't smell like smoke or coolant) gets blown through the cabin.
    2. Car seems to be running rougher since I reconnected my air pump that goes into the intake manifold. Where exactly does the air pump air go to. I know it smog related but . . . . .?
  2. 72GTVA

    72GTVA Administrator Staff Member

    Chesapeake, VA
    1- Are your cowl drains clear? Moisture laden air from defroster can only come from a coolant leak or water intrusion and accumulation from the air induction located in cowl.

    2- IIRC the air pump circulated air into the exhaust ports/catalytic converter to help burn off any remaining hydrocarbons. I wonder if it isn't mechanical vibration or a bearing failing that makes it seem rougher?
    The Wrench likes this.
  3. 65restomod

    65restomod In Overdrive BRONZE MEMBER

    Danville,VT left NJ forever
    Don't rule out a bad heater core, I've seen cores that leak and don't smell like coolant. It only takes 1 drop to fog the glass then it burns off.
    pmrphil and The Wrench like this.
  4. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Seguin, TX
    The 79 335-series had a set of passages in the intake for the Thermactor, with a one-way valve and short tube up front. It may be plugged with a pipe plug, and would look like a vacuum port up front. I'll see if I can find a pic, and the setup should have a dump valve attached to the rear of the pump, or mounted up near the one-way valve.

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