Here you go:
(3) Unit was moved while in operation. Unit was hit with something. Unit fell over.
Solution: Replace the unit to its upright position and restart.
(12) Operated for a long time while the room was closed (i.e. poor room circulation). Filter needs cleaning. Gas cord was stepped on.
Gas valve is shut off.
Solution: Increase air circulation in room, or clean the air filter.
(72) Power outage while operating, or operation was attempted after the plug was pulled from the outlet.
Solution: Wait 2-3 minutes before restarting.
Source
Good Luck!