03 trailblazer hear don't work
When you rotate the directional sw .(upper-heat, lower-heat , defrost etc) do the vents change the flow? There is only 2 possibilities I'm aware of (I'm not perfect) one is the Rotary sw (if it is rotary and not horizontal/vertical) is blocking vacuum or the actuator (a valve that physically changes the vent baffles) is not working
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