ANyone know what could be causing a really loud vibrating noise from the passenger under-dash when I turn the heater on???

THanks in advance!!! I'd like to fix it myself if possible

 

The blower motor is under there - it might have a bad bearing.

 

Is the blower motor accessible?
Thanks for the input!

SOunds like it could be expensive labor

 

Yes it is- check the stickies on the top of the forum - I believe there is a write-up on replacing it... if there isn't, get yourself a Haynes manual for the car - the part is probably in the order of 100-200 bucks... shouldn't take more than an hour or two to replace it.