to the right of the cabin filter is a black panel approx 7 inches by seven inches slightly irregularly shaped, you'll see a wired plug-in connection that is fitted through the panel to the regulator - it pulls out. Should be two white clips that are pushed toward one other to release panel. This is completely different than the narrow panel used for the cabin filter.

if you push the passenger seat all the way back and put a pillow over the car door sill you can lay in there. Tough to get both shoulders into the footwell to use a ratchet socket wrench so try to use screwdriver handles for Torx or just a ratchet extension acting as a screw driver.

If you have a digital camera, once you take the plastic black covering off the blower motor, shoot some picture so you know how the motor and regulator fit back into their space.

Also one you have the blower motor out, use some Lysol spray on a towel to clean ducting and parts