2008 chevy trailblazer auto climate control. My ac/heater blower kept running even after I just the car off. I replaced the blower motor resistor and now blower doesn't turn on at all. Did I b

This vehicle doesn't have a blower motor resistor ! It has a blower motor control module , if you have automatic climate control !
If manual climate control , then there is a blower motor resistor assembly !
Blower Motor Control Processor The blower motor control processor controls the speed of the blower motor by increasing or decreasing the voltage drop on the ground side of the blower motor. The HVAC control module provides a low side pulse width modulated signal to the blower motor control processor over the blower motor speed control circuit. As the requested blower speed increases, the HVAC control module increases the amount of time that the speed signal is modulated to ground. As the requested blower speed decreases, the HVAC control module decreases the amount of time that the signal is modulated to ground.
Air Speed - Front Control
The blower motor forces outside air into the vehicle's interior. The vehicle operator determines the blower motor's speed when the driver places the blower switch in one of 5 blower speeds. The blower motor will always operate in any switch position other than OFF, as long as the ignition switch is in the RUN position. The blower motor and mode switches are located within the HVAC control module. The blower motor OFF input is connected in series with the HVAC control module by the off blower motor control circuit.
Depending upon the selected speed, power is provided to the blower motor from either the ignition 3 voltage or battery positive voltage circuits from the fuse block. The battery positive voltage circuit only provides power when the High blower switch position is selected. Power and ground are provided to the HVAC control module by the ignition 3 voltage and the ground circuits.
Low Blower Speed When the Low 1 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the low blower motor control circuit. Voltage is divided between 4 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
Medium Blower Speeds When the Medium 1 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 1 blower motor control circuit. Voltage is divided between 3 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
When the Medium 2 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 2 blower motor control circuit. Voltage is divided between 2 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
When the Medium 3 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 3 blower motor control circuit. Voltage is divided between a series resistor, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
High Blower Speed When the High blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the high blower motor control circuit. The voltage energizes the blower relay, causing the blower motor to be connected directly to the battery positive voltage circuit. The blower motor and blower motor relay are grounded through the ground circuit.
Go on you tube an check out videos on trouble shooting blower motor circuit
Chevy Trailblazer EXT Blower Motor Won Turn Off

Change the. Blower motor resistor. $25 part near the blower. Chevy suvs are famous for bad blower resistors

Hello! it's my job to make things as easy for the customer as possible...Therefore I must ask why you want to replace the heater switch? Is it because you have lost one or two of the switch speeds? Your vehicle is noted for loss of the Blower Motor Resistor...
Changing the Heater switch means removal of the Climate Control Assembly which is not the easiest of jobs...I've included the process...But are you sure the blower resistor is OK? If you have lost 1,2, or all blower motor speeds it's more than likely the Resistor pack. And a lot easier to change...
Guru...saailer


Remove climate control:

1. Remove the instrument cluster finish panel...
   

1. Remove the 3 climate control assembly screws...

1. Disconnect the climate control assembly vacuum connector...

1. Disconnect the 5 climate control assembly electrical connectors...

1. Remove the climate control assembly..

Removal of blower motor Switch:

1. Remove the climate control assembly.
   

1. Remove the blower motor switch knob.

1. Remove the blower motor switch.
   1. Remove the screw.
   1. Remove the blower motor switch.

Removal of blower motor Resistor:



Blower Resistor is under the battery tray...

MOTORCRAFT Part # YH1698 ...cost $25



Guru...saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

If you have auto climate control, replace the blower motor controle module.

If you have Manual climate control, replace the blower motor resistor assembly.

Both are in the same place, on the bottom of the blower motor itself. Take off the plastic kick piece at the bottom of the glovebox to access the bottom. You'll see small screws holding the piece to the blower motor. From there, empty your glovebox and open it. You'll see an access hole to the left, stick you finger in there and depress the spring loaded piece to drop the door upside down. There you'll have access to the electrical connector from the blower resistor to the blower motor. Very easy job and is a very very common thing to go bad.

For Automatic climate control, you need a new blower motor controle module.

For Manual controls, you need a new blower motor resistor assembly.

If you have automatic climate control, replace your blower control module, behind the glovebox.
If it's manual, replace blower motor resistor assembly, same location.

Good Evening, If I am translating this properly your fan only works on the high setting? And the other settings do not change the speed? If this is correct respond back and I will help as much as possible.

the blower resistor is in the plenum... above the heater core.
If the blower motor does not work at all ... you may have a bad climate control switch.... or blown fuse even... as the resistor is a two stage coil... Low speed and medium speed... no resistor on High and would normally not go at the same time....

Could be your main blower motor resistor, mine would still run the fan even after shutting off the vehicle.(safari van) Had to unplug the resistor to stop the fan,it was near the blower under the hood. Bought a new one for about $45 bucks. Replaced it and all is fine. Might want to check relays first, sometimes they stick and need replacing.
Good luck.