Your furnace is like a human body — it has different parts that work together to keep your home warm and comfortable. The furnace control board is the brain, telling everything else what to do. The blower motor acts like the lungs, pushing warm air throughout your house. The gas valve is like the heart, controlling the flow of gas that keeps the system running. There are even “nerves” in the form of wires and sensors that send signals between parts.
But just like a body can get sick, your furnace can start experiencing problems, too. And when the HVAC control board fails, the whole system can go haywire. If your furnace isn’t working right, you might be wondering: how do I know if my furnace control board is bad? Let’s go over the warning signs so you can get ahead of any major breakdowns.
Signs of a Bad Furnace Control Board
If your furnace is acting up, it could be the control board causing problems. Here are some common signs of a faulty HVAC control board:
1. Your Furnace Won’t Turn On
If your furnace can’t start, the control board might not be receiving power or sending signals to other components. Check your thermostat first — make sure it’s set correctly and has working batteries. If that’s not the issue, the problem could be a faulty control board.
2. The Blower Motor Runs Constantly
One of the most common signs of a faulty HVAC control board is a blower motor that won’t shut off. The board is responsible for turning the fan on and off, so if it’s malfunctioning, the blower motor could keep running even when the furnace isn’t heating.
3. No Heat, or Heat That Shuts Off Too Soon
A failing HVAC control board can cause your furnace to start up but shut off too soon. This can happen if the board isn’t sending the right signals to the gas valve or flame sensor. If your house is still cold even though your furnace is technically running, the control board could be the culprit.
4. Warning Lights and Error Codes
Most modern furnaces have diagnostic indicators (also called warning lights) that flash error codes when something’s wrong. If you see flashing indicator lights on your control panel, check your manual for what the codes mean. Some codes point directly to a bad furnace control board.
5. Strange Electrical Issues
If your furnace has been acting up randomly — turning on and off at weird times, failing to start, or even causing your thermostat to glitch — this can be one of the signs of a bad furnace control board. This can happen due to electrical parts wearing out, loose connection points, or damage to the board itself.
Troubleshooting a Bad Furnace Control Board
Spotting the signs of a faulty HVAC control board is one thing, but knowing how to fix it is another. You don’t want the issue to prevail for too long. If you suspect a bad furnace control board, here’s how to do some basic troubleshooting before calling in a professional HVAC technician.
Step 1: Check the Power
First, make sure your furnace is actually receiving power. Check your breaker box — if the circuit has tripped, reset it and see if that fixes the issue. Also, look at the access door on your furnace. Many furnaces have a safety switch that shuts off power if the access panels aren’t properly closed.
Step 2: Look for Diagnostic Lights
Many furnaces have diagnostic lights that indicate problems. If your control board has a black exterior with a small LED light, see if it’s flashing. Different blink patterns mean different issues.
Step 3: Inspect the Control Board
Turn off power to the furnace, then remove the access panels to take a closer look at the control board. Look for:
- Burn marks or visible damage
- Loose connection points
- Corroded or broken wires
If the board looks damaged, you may need a new board.
Can You Fix a Faulty Control Board Yourself?
If you’re handy and have some DIY skills, you might be able to do basic troubleshooting, like checking for loose connections or error codes. But actually repairing or replacing a bad furnace control board requires working with electrical parts, which can be dangerous.
If you suspect the control board is the problem, it’s best to have a professional HVAC technician diagnose the issue. They can determine if you need a new board or if the issue is with other components like the gas valve, inducer motor, or flame sensor.
Should You Repair or Replace Your Furnace?
If your furnace control board is bad, you have two options: repair or replace.
- If your furnace is less than 10 years old and the board is the only issue, a replacement might be enough to get your system working again.
- If your gas furnace is older, constantly breaking down, or your entire HVAC system is outdated, calling Mike Williams for a full furnace replacement in Springfield might be the smarter choice.
Need help deciding? We can walk you through your options and even offer financing if a full replacement is needed. At Mike Williams, we’re proud to serve homeowners in Springfield, Decatur, Champaign, Bloomington, and all throughout Illinois.
The Bottom Line
Your furnace’s control board is the brain of your HVAC system, and when it fails, your entire system can struggle or stop working altogether. Some of the most common signs of a bad furnace control board include a furnace that won’t turn on, a blower motor that won’t shut off, and strange electrical issues.
If you’re wondering how to know if your furnace control board is bad, you can check for diagnostic lights, test for power, and inspect the board for visible damage. But since the control board deals with electrical components, it’s always safer to call a professional HVAC technician. Trying to fix it yourself can lead to bigger problems — or even safety hazards.
Call Mike Williams for Professional Furnace Services!
If you’re experiencing issues with your furnace and suspect the control board might be the culprit, it’s time to reach out to Mike Williams. Since 1976, we’ve been committed to providing faster, cleaner, and better HVAC services to homeowners in Springfield, Decatur, Champaign, Bloomington, and beyond.
Our team of highly skilled technicians, boasting 180 years of combined experience, is ready to diagnose and repair your furnace issues promptly. Plus, with our 100% satisfaction guarantee, you can trust that we’ll get the job done right.
If you’re noticing signs of a faulty HVAC control board, why wait? Call us today for furnace repair in Springfield, IL, or one of the surrounding areas!