The Furnace Control Board can go bad without any warning sign or tell tale symptoms just like a light bulb can burn out when you flip a switch on.
The furnace control board is also known by many different names throughout the (HVAC) Heating Ventilation and Air Condition Industry.
Furnace Control Module, Furnace Control Board, Furnace Circuit Board, Furnace Mother Board.
Turn off or disconnect the power source to your furnace then remove the access panels.
When replacing your bad furnace control board with a new replacement control board it is a good practice to have the new replacement board out of its packaging or box and to hold it in front of the old board so that you can examine both of the circuit boards and make certain that they are the same before pulling any wires loose from the existing board and replacing.
If you are not familiar with all of the wires that are connected and will need to be disconnected and transferred from one board to the other, have your phone handy and snap a few good photos of the bad control module while it is still connected in your furnace for future reference, if needed.
Now that you know that both of the boards are the same, hold the new one up close to the old one and start transferring the wires from the old board to the
new one, one at a time, using a pair of needle nose plyers. You will need a screwdriver to disconnect the screws for your small gauge thermostat wires. While transferring and reconnecting the thermostat wires, make sure that the outer plastic coating is cut back far enough from the tip of the bare wires so that when you connect them to the new control module you only have bare copper wire touching the plate while you tighten the screws down for a good electrical connection.
Once you have transferred all of the wires from the old board to the new replacement control board you will need to loosen or take the screws out of the control boards housing or mounting panel. Once it is loose and free from the furnace you will need to turn it over and release the control board from the back of the mounting panel then simply align the new control board pins with the holes in the mounting panel and snap it into place.
Now, position the mounting panel back onto the furnace and tighten the screws back. Replace all of the access panels and secure them. Turn the power source back on and your furnace should be good to go and ready for use.
The control board has a life span just like any other household appliance parts do and can wear out from use and age. Lightning storms/strikes cause a lot of havoc on appliances and are responsible for damage to many circuit boards. Electrical power surges and flood waters or just moisture/condensation can also be to blame for a faulty circuit control board.