I had a similar problem, my A/C/Heat on my Toyota pickup stopped blowing air and the Fan was vibrating heavily. Found a nest of chewed up insulation in front of the Evap coil. The Bast@rds had chewed a hole through the fan to get there. Had to replace the fan and clean out the heater area. Looked like chipmunk work , not rats though. Chipmunk poop everywhere. Left eaten acorn shells all over the motor, in the heater ducts, even inside the front door panel. Real PITA.
