If the blower motor is functional when tested directly with the battery but no current is reaching to it when installed chances are the problem is the resistor. It's not uncommon this part gets burned up when for some reason the blower motor gets stuck due to dirt/oxidation inside the blower motor plastic housing.
In my case it just took a good cleaning of the blower motor housing AND a new blower motor resistor - You'll have to take out the glove compartment to get access to it.
I'm sorry I can't provide you with a part number for the resistor -I seem to have misplaced my binder where I keep all my VX records. I got mine for St. Charles Isuzu.
I hope this helps.