It could be a blocked heater core if your fan works... Or it could be your thermostat... I have an 03 that is doing the same thing. I just replaced the thermostat and it is still doing it. There is a site called BlazerForum.com you may get some better answers there
my Chevy blazer power seat on my 1996 Chevy blazer isn't working
you probably have a bad heater core.
1996 Chevy blazer timing chain
what is the distributor setting for a 1996 Chevy blazer
what arethe 3 relays in the glovebox on a 1996 chevy blazer
A 1996 Chevy Blazer Does have a transfer case IF it is equipped with 4 wheel drive
What is your 1996 Chevy blazer LS with a blown motor worth?".
The 96 Chevy Blazer does not have a timing belt.
YES they are the same.
Check right under dashboard on the passenger side of the car. It will be right up against the firewall of the interior.
sounds like ya have a heater core leak . time to take her apart
the 1996 and 1997 are the same and would not work in your 2000 straight from GM