1992 s-10 heater problems...need help

I have a 1992 chev S-10 pickup and have a problem with the heater. The blower works fine, especially on cold air, however, when I switch to hot air, I get very little coming out from the defrost vents on top of the dash.
Most of the hot air (and it is plenty hot) comes out from below the dash from the vent.
Anyone know what the problem is and what is envolved to fix it?
Any help appreciated.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That's how it's supposed to work on the Heater setting. What do you want it to do? If you want hot air in your face, put the selector in "Vent".
--
--------------------

Alan "A.J." Franzman
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Your going to want the check the vacuum lines that control the ducting system. It sounds like the defrost duct isn't opening all the way.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.