The heater blower on my 99 pick up only blows through the defroster. I have changed the dash controls, but still could not direct ait through the dash vent or floor vent. I think the actuator is bad, but I don't know where it is. Does anyone know wher this is located?
Thanks,
On vacuum operated heater contols blowing through the defrost only is a very good sign there is a vacuum leak in the system.
Usually it will be under the hood on the pass side near the firewall. Look for a vacuum canister also.
If its not vac controlled disregard this message.
That is all......
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I had a 99 Sierra that had this. Note that mine was the old body style. Look on the drivers side of the blower housing. Pain in the ass to get there. You gotta lay upside down under the steering wheel. Up the side, there is the actuator that has a small arm assembly that has a spring like device in the middle. This is the bar that turns the fins in the housing. See if it is actually turning when you turn the dial to the different positions.
If it doesn't turn, it is most likely the actuator. If it is turning, and the bar is moving, you got a worse problem. This was my situation.
One of the vent fins was out of kilter inside the box. Getting it into position was a real pain. Then, it simply would not stay in place on the arm outside the housing. I had to screw in a custom retaining bar on the outside of the plastic housing to keep it in place. But it does work. I can take a picture of the bar holding the arm in place if that is your problem, but see if the actuator does turn when you turn the controls.
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