Problem with defoger and air vent blowing.

[Chris B.]

My 1997 Tahoe seems to have a minor problem with the air that is supposed to blow on the windshield to keep it free of fog/condinsation. When I select for the air to flow through the vents it seems that the air does not hit the glass as it should. The air comes through the vents on the top of the dash on the passenger side fine and clears the windshield but it is weak and does not seem to go nearly high enough to clear the glass on the driver side. This results in the glass not getting cleared and makes it hard to see.
The blower blows strong but the air is just not "aimed" right through the fixed vents if you know what I mean.
What might be the problem and how do I fix it? Many thanks!!!!

 

[Chris B.]

Anyone?

 

[Chris B.]

A N Y O N E ? ? ? ?

 

[Oil stain]

When you cycle the control to vent and to heat, does the air come out where it should. On vent sitting does the air come out the dash vents? When you have it set to heat does the air come out at your feet. If so, then the flap inside your dash that directs the air flow to the defroster is stuck and will not close or open to deflect the air to the defroster.

If changing the selector from the dash vents to the floor vents does not change the air direction, then you have a vacuum leak. The internal workings of the controls are vacuum controled.

 

[dwendt44]

Is it a matter of direction or of flow?
I've seem a couple of cases where the flex hose was loose/off the vent end.(under dash) Re-installing hose and clamping with a zip tie fixed that.
Was the truck made on a Monday? the vent could be lose(even though it looks OK) or installed backwards(?). Hey! it happens.

 

[Chris B.]

Thanks guys! When I change from vent to vent the air does change to the vent selected as indicated on the controll selector. When I select for the air to come out on top of the dash so it hits the windshield it does but it is very weak on the drives side and strong on the passenger. You can only feel hot air 1/4 the way up the windshield on the drives side and all the way up on the passenger side. This results in the passenger side defogging right away and the driver side taking forever to defog making it hard to see. How would I go about fixing this? Many thanks!

 

[dwendt44]

Look through the windshield down into the vent(drivers).
Some junk may have fallen down there.
If not that, you'll have to crawl under the dash and check the air hoses. Maybe a kink or a rip, or a hose not completely on the vent molding.
My 2¢

 

[Chris B.]

Ok, I'll do that and report back. Thanks!