Heater blower won't turn off. Even when key is removed.

The blower motor controller is bad , probably . Does your vehicle have manual or automatic climate control ?

HVAC Blower Motor Circuit YouTube

sounds like a blower motor relay or control module. have it check first with your mechanic as the part for your car is expensive. goodluck

Hi that the resistor heater that is shorted out under the glove box remove the plastic cover after that you will see the blower motor and beside that the resistor there 7 32 socket or 5.5 mm change that resistor with a new one saw that problem many time at my shop drain the battery dry when you dont notice it good luck and thank you for using fixya

Depending on the year and model it could be a stuck blower relay.

By the blower motor ,there's a resister,replace.

check ac control unit if you replaced blower module and if your sure fan works

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

Do you mean heater fan or cooling fan?

most likely a blower resister which should be located under the passenger compartment