you probably have a bad heater core.
how to replace a heater core in a 1997 Chevy blazer
Good chance you have a leak in the heater core.
Same as a 96 blazer go here.How_do_you_replace_the_blower_motor_on_a_1996_Chevy_blazer
You have to completely remove the dash to get access to the heater core.
1998 Chevrolet Blazer did not have vent windows.
We need to know what year that S10 Blazer is.
pull the handle down
The windows on a Chevy Blazer may not roll down if the power window mechanism has been damaged or broken. This can be repaired through a reputable mechanic.
The fuse or relay for power windows on a 2002 Chevy Blazer is located under the dash near the emergency brake. It can be readily replaced by pulling it out.
Maybe a bad switch
Right under the throttle cover.
Heater Airbound? Heater control cable not working? Heater core plugged?