your fan is shot or it could be a fuse if it the fan it is located under your dash if you buy the fan you will know what it look like pretty easy to install you can get the fan at any auto part store
Likely heater core. I had same problem with 1996 S-10 with 4.3L.
Frozen/seized clutch pack, time for a rebuild.
try a blower motor resistor
1998 chevy blazer wont start good spark and good fuel presure
my heater fan in front of my 2004 chevy venture van wont work
Because it hates you!
Set fire to it!
did you check your battery and alternator?
I've got a better question, why is this question in the Chevy venture forum ?
Probably a bad fuel pump, not uncommon.
unless ones put in for racing or offroad it wont have one.
Check your coolant. Is it thick and gunky?