The blower motor resistor pack is located between the fireewall and the blower motor on the passenger side. The best way to access this part its to remove the plastic shield under the glove box and then remove the blower motor. Behind the blower motor you will see another wire harness that will be 5-6 wires. This is the connector for the resistor pack. The are 2 screws that hold the resistor pack to the blower motor housing.
I found there to be 3 screws on mine. There is a piece of carpet under glove box that can be removed with taking out 3 plastic snap buttons. I didnt remove the blower. I took out the 2 screws on the sides of the resistor that you can see. You cant see the forward screw. Once the 2 side screws are removed, pry down carefully on the resistor and pull it out with some long needle nose pliers. The back screw hole is slotted, so you can do this. it doesnt come out real easy but it does work. Now that you can see the forward screw with the resistor removed you need to back it out about a turn. All the screws are 7/32's. Now carefully slide the new one in carefully into the forward screw slot. Install the other 2 screws. Also you should have removed the wire plug first thing and the plug from the resistor to the blower fan. Now reconnect them last. This whole job is very difficult because you are lying on the front floor in front of seat trying to get 2 arms in there. I am small. Sorry for you big guys.
On the evaporator case.
Blower motor: remove the glove box and you will see the blower motor and blower resistor.
The blower motor resistor is located on the passenger side under the glove box. Left side. there is a cover on the blower motor. remve the cover, this is the resistor. there is an electrical plug there.
The blower resistor on a 1999 Chevy truck Z1500 is located behind the glove compartment. There is also a resistor on the firewall next to the blower motor itself.
Attached to the blower motor under the passenger dash
If the heater fan works on all speeds, then the blower motor, blower fuse, blower relay, and blower motor resistor pack are all good. If the fan runs but nothing comes out of the vents, you have a 'mode door' issue (which might include a bad control head).
Held in by two screws in a housing just to the left of the blower motor housing.
Inside dashboard in path of air that blower motor blows.
there is a resistor that controls the speed and should be near the blower motor its called blower motor resistor
open glow box and take out computor and it is there on the side of blower motor
There is really no method to "check" the resistor, text by substitution.
it is underneith the passanger dash above the black panel under the dash behind the blower motor