Most of the time on newer furnaces the fan is direct drive off the motor, meaning the blower wheel is mounted right to the motor shaft. The advice above is good IF its belt driven and IF its got oil ports. DO NOT oil it if it does not have the removable plugs Dennis mentioned. It can hurt the motor. If it is direct drive, its likely a bad motor. I run a HVAC company, and we charge roughly $300 to replace motors, depending on size and such. Its not hard, but finding a replacement motor may be, as most supply houses won't sell to the public. Try a "farm" supply store. They have some stuff like that. If you need further help you can call my business at 217-398-5977, ask for Sam.