Have an old HEIL(20 years) that when AC is turned on, the AC works outside, and we can hear some voltage in the house furnace but no motor comes on. Could that possibly be a lack of oil problem and if so where are the oil tubes to add oil? We just noticed the label on the furnace says add oil yearly for maintenance but we have not done that ever. Any help would be great. We can't afford a new furnace or motor yet, so we are trying anything that might work. Thanks