Climate control: balancing the vents

[htheduck]

Has anyone had this problem, I tried a quick search-but couldn't perhaps configure the keywords properly.

The vents are not balanced, either some vent panel/door is jammed-since it will blow a/c to the winshield instead of the vents.
Where do I start to look?

Thanks in advance.

 

[shoclown]

i am having simular problem but mine only goes to defrost after 400rpm. The ac heter ducting goes through a series of tube to go to the vents floor defrost etc.As you select the vent it sends engine vacuum to a servo in which it opens/closes a door to direct the air . If the vacuum or servo is not there than the system will default to defrost(always on defrost then servos direct it else wheere) the doors can also get stuck pencils ,pens etc seem to have found there way in mine in the past.hope this helps..if in your ventures you find a vacuum check valve (one way allows vacumm in but holds it) let me know where you found it.thanks

 

[shogen2]

Yeah sounds like you have a broken vaccum line to the servo or the vaccum line is off.

with the car running try listen for any vaccum leak sounds/hissing or just simply ck for any dissconnected lines under the hood.