Furnaces have a belt that connects the motor to the blower unit. If that belt breaks the furnace motor will run all the time but no air will come out of the vents. Replacing the belt is simple if you place it on the smallest pulley (motor) first, then turn it onto the larger pulley on the blower.

A grinding noise from the furnace or a squealing noise is usually a sign that the bearings in the motor are overheating or may have seized. It is important to immediately turn off the furnace and call the repair professional. Running the furnace at this time will only make the problem worse.

If you have a portable heater, getting heater repair is easy to do. What's more you can take the unit to the heating repair technician which will decrease the cost to you considerably. If you have them come to you, the costs are much more and for not real benefit.