When you turn up the thermostat on a chilly day to warm your home, you may not give much thought to the processes taking place to produce heat and circulate it through the vents. You just assume that the mechanical components will work as they should.
However, the typical furnace is actually a fairly complex machine, and it requires multiple parts and takes several steps in rapid procession to get it running. One of those parts is the furnace control board.
Keep reading for answers to, “What does the furnace board do on most modern furnaces?” from the heating and cooling experts of Georgia Air Cooling and Heating. As the source for the most reliable furnace repair in Richmond Hill, we understand that these crucial parts work and what to do when they go wrong, ensuring your home and family stay warm and safe all season long.
What Is a Furnace Control Board?
The simplest way to explain a furnace control board is to think of it as the brain of the heating system. It’s an essential component, as it ensures that everything happens in the correct order and at the right time so the furnace operates safely and reliably. From receiving signals from the thermostat and turning on the gas and blower motor to shutting the system down once it reaches the desired temperature, the control board handles everything.
You’ll find the control board on most modern furnaces inside the access panel, usually below the blower motor. It’s usually green and has multiple wires and connections to other parts of the machine.
Types of Control Boards
Although the answer to, “What does the furnace control board do on a modern furnace?” is fairly straightforward, the part’s specific functions vary depending on the type of furnace you have.
Older furnaces generally have a simple ignition control board module and a separate control board for the fan. The ignition control board manages the ignitor, the gas valve, and the flame-sensing circuit.
Modern furnaces have an integrated control board that runs the fan and the ignitor, gas, and flame-sensing circuit. Combining the two boards into one helps improve efficiency.
How Does a Furnace Control Board Work?
A malfunctioning furnace control board can cause multiple issues, any of which can keep your home from warming up. In fact, a better answer to, “What does a furnace control board do on a modern furnace?” might be, “What doesn’t it do?”
The control board is part of almost every step of the heating process. Wires connect it to the thermostat, gas valve, ignitor, blower, and other critical components. It receives and sends signals from each part, triggering the heating cycle.
To give you a better idea of how the control panel works, consider the typical heating sequence:
- The thermostat detects a lower-than-desired temperature and signals the furnace to fire up.
- The control panel turns on the induced draft motor, causing a pressure drop that, in turn, engages the pressure switch.
- The pressure switch closes the circuit, signaling the control board to start up the igniter.
- The board sends a simultaneous signal to the gas valve, causing it to open and release gas to the burners, which instantly ignite.
- The control board turns on the flame sensor, ensuring gas continues flowing while the furnace heats up.
- The blower motor comes on when the board sends the signal, moving air through the furnace and into the ducts.
- The thermostat sends another signal to the control panel when it senses the desired temperature, triggering the furnace to shut down.
If there are any faulty connections or other issues with the control panel, it can impact one or more steps in the sequence. When this happens, the furnace may not work as efficiently as intended, fail to produce adequate heat, or not work at all.
Signs of a Problem With the Furnace Board
It’s easy to mistake problems with the furnace control panel for issues in other parts of the heater because it’s so integral to the overall function of the system. However, if the furnace board fails, you’ll have problems operating the heat and notice a few telltale signs.
Illuminated Diagnostic Lights
Most boards have LED diagnostic lights that flash in a sequence to indicate a specific problem. The lights flash in a code that reveals what’s wrong; the board typically has a chart to help you interpret the code and determine the best course of action.
If the diagnostic lights do not illuminate, it could be a sign that the panel needs a reset. To do this, turn the furnace power off and then back on. However, even if the furnace comes back on without flashing an error code, call an HVAC technician to inspect the panel, as you shouldn’t have to reset it.
Unpredictable Furnace Cycles
If the furnace struggles to fire up, short cycles on and off without producing any heat, or won’t come on at all, the furnace board could be the problem. Some homeowners describe the furnace as stuttering or report that it turns off without completing a full cycle.
Unstable Temperatures
A functioning furnace shouldn’t have any trouble keeping your home warm and cozy consistently. If the temperature seems to fluctuate wildly throughout the day, a faulty control panel could be the reason why.
Why Furnace Boards Fail
Despite being one of the most essential parts of a furnace, it’s common for control boards to have problems or fail. Some of the most common reasons for control board failures include:
- Loose wiring
- Dirty or blown fuses
- Clogged air filters
- Broken starting capacitor
- Malfunctioning blower motor
- Power surges
- Power outages
- Lack of furnace maintenance
- Excessive wear and tear
- Age
In general, you can expect the typical modern furnace control board to last 10 to 15 years. Considering most furnaces last about 15 years before needing an upgrade, it’s reasonable to expect the board to last for the entire lifespan of your equipment. If your furnace still has plenty of life, installing a new control panel is a more cost-effective solution.
How Technicians Troubleshoot a Control Board
When you call an HVAC professional to service the furnace and determine whether the control board is the culprit for heating issues, they’ll use several methods to troubleshoot and diagnose the problem.
They start with a visual inspection to determine whether the board has any obvious signs of damage, like scorch marks or odd odors, which indicate the panel is bad and requires replacement. If there aren’t any signs of an immediate problem, the diagnostic lights may have the answer.
If the indicator lights aren’t working, the technician will test the power and the terminals using a voltage meter to ensure that the board is getting enough power to operate various functions. If the voltage meter shows power coming to the board, the technician will isolate the terminals to determine which is malfunctioning and make the necessary repairs. No power to the circuit board means the panel is bad and needs replacing.
The Importance of Maintenance to the Furnace Control Board
Now that you have the answer to, “What does the furnace board do on most modern furnaces?” it’s easy to see why regular furnace maintenance needs to be a priority. An annual service visit by a qualified HVAC technician helps ensure that the board is in good condition, all the electrical connections are tight and working properly, and nothing is happening with the panel that could cause problems in the future.
You can also help keep the furnace control board in good condition by changing the air filter every 60 to 90 days or at the interval your technician recommends. A dirty air filter blocks airflow and causes the furnace to work harder, putting more strain on the control panel. Excessive wear and tear can damage the connections and sensitive electrical components in the panel, so keep up with air filter changes to extend the furnace’s lifespan and preserve indoor air quality.
Trust Georgia Air Cooling & Heating To Keep Your Furnace Running Reliably
The next time you fire up the furnace, you’ll probably think about all the complex processes that are taking place and the precise processes and timing that have to work perfectly to keep your home warm. At the first sign of a problem, call a professional for help to ensure your family’s safety and comfort and prevent issues from worsening to the point of expensive repairs or an unplanned furnace replacement. If you suspect a problem with the control panel, have more questions about things like, “What does the furnace board do on most modern furnaces?” or want to schedule a professional furnace tune-up to prevent costly repairs this winter, call Georgia Air Cooling & Heating at (912) 513-3756. Our friendly team of NATE-certified technicians will be there quickly to handle even the most complex issues and restore total comfort and reliable operation. Be sure to ask about our PeachCare Club Maintenance program for even more peace of mind.