Have a 99 blazer and cannot get the heat to switch to the floor. Just had the transmission rebulit and they did change the the vacuum switch on the transfer case. I know that can cause a problem with the control My question is do they still make the control for the head unit and if so where do i go get it and what is the technical name for this. I tried one out of junk yard and it didn't work either. My wife would really like some heat on the feet.

 

*Moving to 2nd Gen Tech* - Technical questions belong in the appropriate technical section. Please read the section descriptions and choose the one that fits your question the best.

Can you switch it between the dash vents and the defrost vent or is it pretty much stuck? If its stuck, where is the air coming out of?

 

it may be tied to the vac lines or the "damper" (lack of a better term) that moves to control air flow in the hvac plenum in dash may have snapped. mine did that one winter...i went to change the air flow and then i lost air to the floor. the plastic gets brittle and snaps at the connection point in the plenum.

this link may help if it turns out to not be a vacuum issue

https://blazerforum.com/forum/2nd-generation-s-series-1995-2005-tech-41/98-blazer-no-floor-heat-17808/