Ventilation/heating system makes a shhhhh-ing noise

When I turn the ventilation/air-conditioning control on my 2000 Taurus, it makes a shhhhh-ing noise. I know that something needs replacing, as I only get air from the vents when it's set at full blast. The car is going in on Tuesday to get that fixed. Any ideas if this noise is caused by the same problem?

Thanks

There is what are called blend doors inside of the air box inside the dash. If you only have air coming from certain areas there may be problem with the motors on the blend door. If one is partially open it would give you a stange kind of whistle, sshhh noise.

The shhhhh-ing noise is pretty normal - our cars have vaccum operated blend doors in the HVAC system, and air has to move around AND sometimes escape, for the doors to move into their designated positions.

But yeah, if there's a problem with your system, you could be hearing more than you're supposed to.

You say you only get air from the vents, when running full blast? Does that mean that the only time the blower motor runs, is when the fan speed control is all the way up?

Does moving the vent control make the air come out where you want it to? As in, air blowing out the vent and/or floor, when that is where you set the control to? If you have a major vaccum leak, the air will only blow out the defrost vents, no matter where you put the vent control.

I got the problem fixed - it was only blowing out air at the highest setting. Now it works properly. It was some kind of sensor, which I think was mentioned in another post.

Thanks