Mysterious Fan Electric Ghost
 

My 91 Miata continues to drain the battery during the night sitting in my garage with the ignition off. I changed out the changed the battery and then the relay. Two days later the new battery was dead. I recharged it and walked out into the garage a few days later to find the Miata fan running full blast with the ignition off. Could the temperature sensor cause this issue with the ignition turned off or does anyone have any other ideas? I am currently just pulling the main fan fuse when I get home from driving so the battery doesn't go dead. thanks