The blower motor is removed from under the hood. Against the firewall just to the left of center you will see the blower sticking out. Five 5.5mm bolts hold it on.
It is in the middle of firewall between the engine compartment and the passenger compartment.
in my 89 Oldsmobile delta 88 , the heater motor was directly under the center of the windshield under the hood. black circular thing.
Probably the heater core, it is a beast of a job to do, but is gratifying to say the least. If the is a smell of antifreeze you can almost bet it is the heater core.
The heater core may be stopped up. Try flushing it, or replace it.
How to change a timing chain in a 1998 Oldsmobile delta 88
if not your fuse, check the fan/blower relay.
$65.00
Directly behind the engine, on the middle of the firewall.
They are generally located close to or near by the blower motor.
under the hood on the fire wall.
Screwed into the heads.
if there is a lot of snow or ice on these vents located at the bottom of the wind shield under the wipers that could be the problem if you live in a cold environment.