Thankyou for replying!
The furnace has a thermostat. This Timer im talking about is conected to a selenoid "flapper" that on one side is a round insulated duct (that im sure brings in fresh outside air) and the otherside is conected to the "air in" side of the furnace. The Programable timer is just on manual. So can you tell me (with this new information) what is the purpose of this timer and how it should be set?