Hvac blower will not shut off and will kill the batt

https://www.autogenius.info/cadillac-deville-1999-fuse-box-diagram/#:~:text=Cadillac%20DeVille%20%281999%29%20%E2%80%93%20fuse%20box%20diagram%20Year,block%20on%20the%20driver%E2%80%99s%20side%20of%20the%20engine.

It's probably not going to be a fuse issue , you people have limited thinking because you have no clue how the electronic's work on your vehicles . The HVAC contol module as battery supplies yes , but control the blower motor with PWM - pulse width modulation controller .

Blower Motor Control Processor
The blower motor control processor is an interface between the HVAC control module and the blower motor. The blower motor speed control, battery positive voltage and ground circuits enable the control processor to operate. The HVAC control module provides a pulse width modulation (PWM) signal to the control processor in order to command the blower motor speed. The processor supplies 12 volts to the blower motor through the blower motor voltage supply circuit. The control processor uses the blower motor ground as a low side control to adjust the blower motor speed.

Most of the time the Blower Motor Control Processor is bad , without testing this is just a guess . Your best bet , take your vehicle to a qualified repair shop.

If you pull the top left fuse, it should kill the blower motor till you figure out the problem. I don't know if you have automatic hvac or manual?

If the blower motor won't shut off, pull the blower motor relay in under hood fuse box. That should kill it till you find the problem. I don't know if you have automatic hvac or manual hvac?
Can you check for hvac trouble codes? Some of the national brand auto stores will check codes for free.
If blower motor wiring connector has both voltage and ground, it will run as long as the battery has voltage.
I saw two different wiring diagrams on your blower motor, I don't know which one applies?

You probably have a bad blower motor control module .First check the Batt. 4 fuse 30amp in the under hood fuse box .
Blower Motor Control Processor The blower motor control processor is an interface between the HVAC control module and the blower motor. The blower motor speed control, battery positive and ground circuits enable the control processor to operate. The HVAC control module provides a pulse width modulation (PWM) signal to the blower motor speed control processor in order to command the blower motor speed. The processor supplies 12 volts to the blower motor through the blower motor voltage supply circuit. The control processor uses the blower motor ground or low reference as a low side control to adjust the blower motor speed.

Do you have The Automatic or Manual HVAC system ? Doesn't matter fuse's are the same ! Out in the under hood fuse / relay box are two fuse's for heater HVAC BATT fuse #39 10 amp an # 70 40 amp . HVAC BLWR . HVAC = heater ventilation an air conditioning ! So Tom what problem are you having ? Heater fan not working ? There is also a blower motor control module involved !

You most likely have a bad fan limit / cycling switch. If you kill the power to the furnace see if you can trace the wires from the motor to where the connect to the switch. It looks like a round button with tabs sticking out of it for the wires to connect. Mark down where the wires were connected and take it to a HVAC business or furnace supply house. Be sure to have the model off the furnace with you so you can get the correct parts.

Your impala doesn't have a resistor , it has a blower motor control processor and it doesn't work the way you think it does
Chevy Trailblazer EXT Blower Motor Won Turn Off
Blower Motor Control Processor
The blower motor control processor is an interface between the HVAC control module and the blower motor. The blower motor speed control, battery positive voltage and ground circuits enable the control processor to operate. The HVAC control module provides a PWM signal to the control processor in order to command the blower motor speed. The processor supplies 12 volts to the blower motor through the blower motor voltage supply circuit. The control processor uses the blower motor ground as a low side control to adjust the blower motor speed.

HVAC Blower Motor Circuit

HVAC drain tube was blocked and condensation could not drain to the outside of the vehicle

as a result the water pooled inside the HVAC case leaking on the inside and killing your blower motor and probably blower motor resistor

clear the drain, replace the blower and resistor and you'll be back in business