Gotta find your SPECIFIC schematic ! Most blower ckts have at least one relay AFTER the fuse , some two.
A single relay usually kicks "ON" the whole shabang - power to "resistor" (Transistor= modern ver.'s) and blower.
Then the second relay (IF used) can be for DIRECTLY "shorting load side to ground " thus giving Max BLOW and thus saving the controller OR resistor to NOT deal with the highest current stresses !!
I'm right now troubleshooting my daughter's car.
Tip: Locate and "expose" - Blower motor ,and ALL relays for Blower/AC . Now if & when NO-BLO try and give a good "Rap-A-Tap" with mallet or screwdriver handle to each of those componants. Relays may engage poor contacts AND motor may get "Bumped Out" of the dead-spot it's stuck in ?!?!
Ya see if ONE or more are culprets.