Blower and heat exchanger cleaning

I note a whistling sound from the furnace. Filter is ok. Removal of the fan assembly indicates a dirty heat exchanger and blower wheel. This video is part of the heating and cooling series of training videos made to accompany my websites: www.graycoolingman.com and www.grayfurnaceman.com to pass on what I have learned in many years of service and repair. If you have suggestions or comments they are welcome. If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits.