Poor heat

I have a 2000 S10. Im getting little heat if any. When i do have little heat coming out and when i stop (or idle) it will blow cold air. Changed thermostat and had flushed. I heard the vacum lines behind heater box causes this. Is this true? I searched this forum and really couldnt find anything. What could be causing this? Thanks Dan

Does your truck have 4WD ? I know the trucks with 4WD have an issue with tranny fluid sucking up into the vac system. Try posting it at this site if you can't find your answer. Its a great site with very helpfull people. http://www.s-10crewcab.com/og1/crewcab.htm

It is 4wd.

This is the problem that the 4wd S-10s are having with the hvac controls.

http://www.s-10crewcab.com/phpBB2/viewtopic.php?t=3197