hey everyone new to the site I got a 88 blazer 4.3 last week and im fixing her up when got it the air blew strong through the vents but all of a sudden it stopped blowing through any vents and the blower is working.. I cant figure it out. all the vaccum lines ive checked have vaccum any advice?

 

usually it defaults to defrost if no vacuum is present, if you dont feel it coming out of anywhere, could be a few issues. ive actually bought a 85 s10 where someone installed the wrong direction blower motor into it somehow. so at full speed it was blowing like it was on low speed cause the squirrel cage was going in the wrong direction. but doubt thats the case if it worked when you got it.

another thing i can think of from experience is a mouse moved into your heatercore, seen them build houses in there and clog up the heatercore but again you should still have some air flow

you can try pulling the blower motor out to see if thers a obstruction. also switch the settings around from floor to defrost to vent and see if you can hear the doors moving

 

possibly something clogging up somewhere since im getting vaccum...I do move the door on the passengers side kickpanel but still nothing...

 

You might also check to see if the air diverter doors in the heater case are broken or jammed.