a loud noise when trying to defrost my windows

The defroster uses the AC evap coil to dehumidify the air blowing on the windshield, so you may have a problem with the AC compressor. Try switching on and off the AC and see if you hear any noises. (The AC compressor is one of the accessories mounted to the engine and ran off the serpentine belt, so check compressor, pulley, and belt.) Another potential source for noises are the mode and/or blend doors, which direct air inside the dash to different vents. Cycle the doors and again listen for any noises. The doors are moved by actuators, which are little geared motors and can fail.