a couple of things can be going on here. if there is a leaf stuck in the blower motor it can cause this problem. just remove the blower motor and clean all the stuff out. alos you might want to replace the cabin filters also. secondly if water got in there and there is rust all over the bearing on the blower you are better off just replacing the motor. check in the engine compartment where the fresh air goes into the cabin and see if the drain on the bottom is plugged. this happens quite often and can be a real problem. water gets into the passenger compartment and goes all the way back behind the passenger seat and takes out the rear sam module. this is only in some cases. hopefully there is just a leaf stuck in there. hope this helps