Please help. In 2002 we bought a new furnace and airconditioner. In 2008 had to replace the exhaust blower(1 year warrantee). Now 2 years later it is making a whining humming sound when it comes on, we are getting plenty on heat but the noise is terrrible! I hate to have to spend another $700 for 2 hrs if that of work, can I check it myself?Make Tempstar Model#N9MP1075B12A2

Is this a gas or oil furnace? Is this blower a power venter? If you have oil heat you need to have the service done once a year by a decent company to keep everything clean. Gas requires less maintenance. Have you lubricated the motor ever? Depending on the manufacturer they recommend doing this every 1-2 years (I am assuming you have a power-venter or direct vent system). Check the manual that came with it, but it usually requires a synthetic lubricant - 3-5 drops in each of the oiler ports.