If the switch is OK & you need a new motor, install it from the outside. Disconnect the wires from the inside first. Go outside & remove the cover with 2 philips screws, gently pull off the plastic fan blade, remove the motor with 2 small philips screws. Be careful with the fan blade. The blade on my 1989 MH cracked during removal. It wouldn't hurt to order one & keep as a spare if you don't need it. That way the installation won't be held up while waiting for the replacement to be shipped. Protect the AS side with a towel or something from the ladder.
"Sometimes I wonder if the world is being run by smart people who are putting us on, or by imbeciles who really mean it." Mark Twain
AIR 22749 WBCCI 2349 NOVA TAC TN-6
1989 345 LE Classic Motorhome