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The Failed Furnace Control Board: A Major Furnace Problem

electrical-schematicA natural gas furnace may burn gas to create the heat sent into the home, but the furnace also uses electrical power to run. This is why your furnace won’t work during a power outage, and also why you may need heater repair in Madera, CA to repair electrical components in your furnace at times. In fact, electrical malfunctions are among the more common type of furnace problems. We’re looking at one of these major malfunctions today, which is a failed furnace control board.

What Is the Furnace Control Board?

The control board is the central “brains” of how your furnace operates. It’s a circuit board that controls such functions in the furnace as the ignition, gas valves, flame sensor, and blower motor. The newer furnace control boards often integrate the air conditioner controls as well, so this board is a true “central operating station” for handling an HVAC system.

How the Control Board May Fail

Any complex piece of electrical equipment can fail in different ways. Although control boards are built to be durable, they may not always last for the entire life of a furnace.

  • Damage from power surges: A power surge in your house that may not cause your lights to go out might still secretly do damage to the transformer in the furnace control board or burn out the board’s fuse.
  • Stuck relay switches: The control board contains miniature relays to send power to components. These relays can become stuck open and refuse to close, which can occur because of dirt, loss of their protective coating, and warping leading to misalignment. Older furnaces have electro-mechanical switches that may become permanently stuck.
  • Failed transistors: The transistors in the control board are susceptible to damage due to power surges, static electricity, and age. Transistors are often the first part of a control board to fail.
  • Loose wiring: The vibrations of the furnace over the years can cause wiring in the control board to shake loose. The most immediate effect of this is to create an electrical short, and this is one of the reasons your furnace might trip a circuit breaker in the house. If resetting the circuit breaker doesn’t get the furnace running again, please call us for repairs to see if loose wires on the control board are the problem.
  • Aging over time: Years of stress from the above elements, such as thermal expansion, vibrations, and surges, can cause the control board to degrade to the point where it fails. If age is the issue, then the furnace may have reached the point where the better repair isn’t to replace the control board, but to replace the furnace.

If you notice that your furnace is turning on and off at strange times, doesn’t respond to thermostat settings, is making excessive clicking noises, or its blower won’t stop running, then you may have a furnace with a control board that’s failing. We recommend shutting off the furnace and calling us. Don’t try to fiddle with the control board yourself! A gas furnace is not something you want to tinker with unless you’re a trained professional.

Call Purl’s Sheet Metal & Air Conditioning for furnace repair service. “Quality Is the Cornerstone of Our Success” since 1952.

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