The induced draft motor moves the hottest of air in the furnace. The temperature of the combustion gas can be as high as 400 degrees Fahrenheit. As we all know, when something is heated it expands, and when it is cooled it contracts.

The bearings on the induced draft motor work the same way. If you hear a whining noise coming from it, there is not much you can do. The bearings are sealed. The noise is most likely coming from the bearing expanding from the heat. The rubbing bearing causes the motor shaft to slow down resulting in a whining noise.  You best bet is to be proactive and replace the induced draft motor when you first hear the whining nose. There is not much you can do to get the furnace to run with a bad induced draft motor on a cold day.