No Air Coming Out Defroster Vents

no air from defrost ventsMy Chevrolet ¾ Ton Pickup standard has a problem. The windshield defroster vents quits blowing air/heat. Air comes out of all other vents, just not the windshield defroster/dash vents.

Do you have any ideas what I could look at myself for a quick fix?


Hey Mike,

Two things come to mind here – A bad dash control switch or a bad diverter door motor in the dash. The diverter door or blend door motor as it is sometimes called diverts the airflow from the blower motor to the desired vent location inside the vehicle.

Either this motor is not getting the signal from the dash control switch or the motor is just not operating in that mode.

I have seen pencils and other debris fall down the defrost vents on top of the dash and get lodged in the diverter door motor causing the defrost selection not to function.

Both of these items can be tricky to test and not easy to get to, so I am not sure how mechanically inclined you are and what testing and repairing you can do yourself.

Please share this with your friends,
Austin Davis

Posted in: A/C and Heating

4 Comments on "No Air Coming Out Defroster Vents"

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  1. Ron says:

    I had never heard about a diverter door in the dash before, but that is what my mechanic says is the problem with my a/c. blows out defrost setting.

    • By Austin Davis says:

      Yes Ron, there is a TON of parts inside your dashboard. The diverter or “blend” door is what directs the air flow from the blower motor to the correct chamber inside the dash.

      The a/c evaporator is what produces cold air, and the heater core is what makes hot air. That blend door directs the air flow to the appropriate source as you direct by the dash switch.

      Switch the setting from heater to a/c and you can sometimes hear the door move in the dash on the passenger side and you can hear and feel the velocity of the air flow change.

  2. Roger says:

    I had a problem with the blend door you talk about, I dont recall what my mechanic said exactly but he said that a piece of plastic on the door itself had broken and was not allowing air flow to the defrost selection.

  3. Violet says:

    Thanks Austin, have a wonderful day. Shared your site on Facebook. Should be a blessing to my group of friends as well as me.

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