I have a loud squeak coming from my furnace blower. The A/C is working fine as there is plenty of cold air. I cheked the blower and it appears that the squeak is coming from the fan itself. I have a Heil 7000 that is at least 12-15 years old. Does the fan assembly just need lubrication? There is also some dust around the motor. How much damage will I do to the furnace if I keep the A/C on and blowing?

Could be a loose or broken fin/blade, maybe a little loose on the motor shaft,a good cleaning might help as the fan could be a little out of balance,, one thing for sure it won`t fix its self and will only get worse, most motors made in the last 20 years don`t have a port to oil but take a look see, you might be the lucky one

Well, after a thourough cleaning the fan ran for about 2 hours, then the squeaking came back and is now constant. One thing I notice is that when I turn the fan off it almost seems like the blades are rubbing up against something as it slows to a stop. The problem is that I can't get a good look because of the tight space the furnace is in. We have a maintenance guy coming in a ltiile bit to take a closer look.

Thanks for the advice though!