The blower resistor is not under the dash on this vehicle, it's access via the engine compartment, through the firewall. During vehicle assembly, the blower motor resistor is mounted to the dash plenum panel inside the passenger compartment prior to instrument panel roll-up. However, a resistor mounting plate has been designed so that the resistor can be removed through an access hole in the cowl plenum panel just below the windshield. It can be accessed by removing the cowl plenum cover/grille panel.
Reach through the cowl plenum access hole to remove the two hex screws that secure the blower motor resistor to the cowl plenum panel.
Pull the blower motor resistor and its wire harness out of the plenum panel and through the cowl plenum access hole far enough to access the wire harness connector.
Unplug the blower motor resistor from the wire harness connector.