Check for loose wire connections also
Defective blower motor or resistor pack. Blown fuse or defective blower motor switch.
either a bad fan switch or a bad blower motor. Take it to a trusted mechanic.
it wont blow heat itll blow cold air
The heater control valve is stuck open.
If it does not blow at all then that is a problem, but if it is when you first start it, the Caddy will not blow air on you until it is the selected temp.
Your heater core is likely bad
check heater fan to see if it is working.
Likely heater core. I had same problem with 1996 S-10 with 4.3L.
underneath the dashboard on the passenger side.
you need a new blower motor resistor
Have you checked the 30 Amp fuse ?
Low coolant? Thermostat not opening? Plugged or restricted heater core? Heater core airbound? Heater valve control cable detached or broken?
check you antifreze level if it is low you wont have eat or if you get lots of fog your heater core is bad