Woke this morning to a half way cool home. Heard the central air conditioner shut off and all of a sudden I hear this clanging noise from the furnace. HELP:eek:

The only thing moving in your furnace is the blower motor cage. It sounds like the motor shaft is worn and the cage is rattling against the plenum.

If you've never changed a motor before, call an HVAC tech for this, as this may possibly be your problem.