Interior blower fan dead...blowing fuses.

[phyrefighterjay]

O7 Yaris 4 door well fellas here it is....A long time ago I had receipts that got stuck in my blower motor and ruined the first three speeds leaving me only with speed number four. For five years fan speed number four was very good to me. Then the blower motor finally Quit. I purchased another blower motor off of eBay for $65 and that worked on the fan speed number four for about a month. Once again with the replacement blower motor the previous three speeds did not work. The replacement blower motor would work every once in a while after hitting it softly with a rubber mallet. But not for very long...now all is kaput. I started with the fuses and realized that my 40 amp fuse under the hood was blown the interior 7.5 amp fuse was fine. I replaced the 40 amp only to have it blow immediately. I then moved to the rheostat/resistor and found that it was blown. Replaced the rheostat/resistor. Now I am befuddled to what is going on. I have a multimeter. Now what do I do? Obviously something is wrong with a ground here? Please help.