Though forced-air furnaces are normally quite reliable, they can break down and, when they do, getting them fixed quickly is usually critical. With a little do-it-yourself experience and the proper guidance, you can troubleshoot and repair a variety of furnace problems yourself.
  Gas Furnace Parts Diagram
 
Once a year, vacuum out the area around the furnace’s blower. If possible, slide out the fan unit, clean each fan blade with a toothbrush, and then vacuum with a brush attachment on a vacuum cleaner. Look for oil ports on the motor, normally located near the motor shaft. If the motor has these, apply two to three drops of non-detergent motor oil into each port (you may have to remove a cover plate to do this). Most contemporary motors don’t require lubrication, but motors with oil ports should be lubricated once a year.
 
The information in the following articles is for some of the most common types of repairs. If these look to be beyond your abilities, call a qualified HVAC repairperson.
 
If you suspect a furnace gas leak, deal with this immediately! If you smell natural gas in your home or near the furnace, do not light any matches or turn off or on any switches. If the gas odor is strong, immediately evacuate your house, leaving the door open. Turn off the gas supply valve, which should be located by your gas meter on the gas inlet pipe, by rotating the valve one quarter turn with an adjustable wrench so that the valve’s oblong stem is perpendicular to the inlet pipe. Then call your gas utility or the fire department from a remote location. Do not return to your home until you know it is safe.