OK I have a problem with my A/C / Heat system. It only blows hot air from the top dash defrost vents and the floor board vents, nothing comes from the vents that face and blow towards me. Anybody that can tell me what the problem is or where to begin to look?

 

oh hey, do a search for HVAC and lots of info that way. however under the hood by drivers side brake booster is a vac line that has a 3 way plastic fitting, check all lines there in all directions that they're in good shape. again not sure of year of your truck or that all trucks have it but what the hey. its something to go on. Also check my post i wrote within last two weeks.

My assumption is the vacuum that powers the heater controls comes via the 3 way splitter into the cabin

 

https://blazerforum.com/forum/2nd-ge...no-heat-14749/

 

probably a vacuum line, mine was doing the same thing. It cost me a whopping 1.63 for vacuum lines.

 

This isnt the same setup as mine.

 

Where does this vaccum hose attach to? Comes from driver side firewall under the big metal circle piece attached to drivers side firewall...

https://youtu.be/r_UWpFHxokk