Driver/Passenger vent not working

[lak8]

Hi all

Everything is working great with my truck (99 ranger) but the only problem im having is:

I noticed it dosnt blow much air if any, out of the driver and passenger side vents. The middle two middle vents blow just fine its just the side ones (driver/passenger)

-The Vents are open!
-My ranger didn't come with a/c
-It switchs fine thoughout all the settings (floor,vents,defrost)

What could be the problem? its been like this ever since i bought it

 

[97XLT]

I've got the exact same problem..All my heat blows out the defroster vents, onto the windshield. Lucky you, mine don't even blow out the middle two vents. The only heat source I get is putting my hand on the little window defroster vent..

 

[lak8]

My guess is you have a vacuum leak some were. Most common place is located in the engine bay near the passenger firewall. i think its a white tube that mostly corroads or gets damaged

 

[metalmacguyver]

x2 a vacuume leak is likely.