Originally Posted by dude

I'm pretty sure most modern cars draw air into the cabin from the low pressure area at the base of the windshield. In fact when you replace cabin air filters you often have to pop off that large plastic piece under the windshield wipers to access it. This is when the knob is selected in the "vent" position. When in "recirc" mode most just recirculate the air already in the cabin by a flapper door that opens near the passenger footwell.

Having said that, my BS detector is pinging. The cup on the ground had nothing to do with a critter in the blower motor fan. The fact that you even related the two is incredible. The fact you took the fan out yourself should have convinced you of the routing of the air. The only way that happened was if a mouse entered your car and somehow either chewed through your A/C duct and walked its butt into the blower fan...or it was Houdini Mouse and managed to get through the air passageways under your windshield. Or, someone took a rat, threw it in a basket fan and decided to place the phots on a message board. Either way, everyone reading this lost precious moments of their lives that they will never get back. And I lost even more composing this. Please let this thread die.