1993 740iL Battery Drain

Hello, I was messing around with my timed automatic ventilation system in my 740iL. I set it yesterday and it came on like it was supposed to. But when i came back after it had shut off an hour earlier, i heard that the fan was on really really low. If i wasn't listening for it i wouldn't have heard it. I tried hitting the timer button to make sure it was turned of and it was, but it still sounded like the fan was on. So I left it figuring it would hopefully turn off in another hour or so. The next day i went to get into my car, disarmed my alarm (noticed the horn was very quiet), and when i went to start it what do i get? A dead battery (a whole bunch of clicking from the starter). Now i don't know about you, but i had no idea that my battery would be that dead. So I got my car jump started and now it operates fine. But i don't know if my battery is going to drain again tonight or not, seeing as how i had gotten it jump started this morning. Now i KNOW that i have the timer turned off, but does anyone know why my timer would be dis functioning and possibly know how to fix it? My car gets really hot in Florida during the day and it would be nice to have my ventilation system working.
Any help would be much appreciated!
Thanks

replace the blower motor resistor, also known as the fingers of death. THIS WILL CAUSE THE BLOWER TO RUN AT strange times when the car is not running.