How do you know if a control board is bad?

Use some tape to keep the switch pressed down. If your control board has 120 volts AC going into it, then it has power. If your control board has power, but it’s diagnostic light is not on, then the control board is likely bad and needs to be replaced. NOTE: You’ll need a multimeter to test for power in your furnace.

How do you test a control board?

How to Test a Circuit Board

  1. Key Takeaways. A list of basic tools for circuit board testing.
  2. Start with a Visual Inspection. Look for burnt components during your visual inspection.
  3. Check the Power Module.
  4. Check the Input/Output Ports.
  5. Check Communication Ports.

What Causes Control board Failure?

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.

How do you test a bad furnace circuit board?

Here are signs you may have a malfunctioning furnace control board: Uncomfortable temperatures: If your furnace starts to make you either too hot or too cold, and the thermostat settings seem fine, then the problem might be a control board that is turning components off too soon or letting them run too long.

How do you test a control board with a multimeter?

To test circuit board properly, touch the multimeter probes to the test points present on the board. Make sure while playing out this step you have your hands on the plastic portion of the probes. You can then go on to check either the voltage or resistance.

How often do furnace control boards need to be replaced?

10 to 15 years
A furnace control board lasts 10 to 15 years on average.

How do you tell if a fuse is blown on a circuit board?

Remove the fuse from its holder. In some cases you may need a small screwdriver to unscrew the fuse holder cap. Look at the fuse wire. If there is a visible gap in the wire or a dark or metallic smear inside the glass then the fuse is blown and needs to be replaced.

What causes a burnt circuit board?

Boards might burn because of poor protections. If the board connections are hooked up incorrectly or attached to the wrong type of power supply, leading to eventual burn out. In addition, if installation documents are confusing or nonexistent, a field technician might hook up the board improperly.

How do I know if my circuit board is working?

How do you check a fuse on a circuit board?

Another way to test the fuse is by measuring the voltage across it with a digital multimeter. This is helpful if the fuse is not able to be easily removed from the circuit. To do this, leave the circuit powered on and switch your meter to measure voltage. Make sure to select DC for DC circuits and AC for AC circuits.

How do I know if my control board is working properly?

This is very easy if your control board has an indicator light. The indicator light is an LED light that blinks when the control board is getting power. If your control board has an indicator light, and you see it’s working appropriately, you’re in luck! Skip down to step 9.

How to check a circuit board for faults?

So, for the proper use of your instruments, it is beneficial to know how to check a circuit board for faults. A circuit board is made of many components, and so, an array of defects may appear on the board diameter. Although the list may seem a long one, you can quickly check the faults with a multimeter.

What causes a control board to go bad?

Control boards can go bad for many reasons. A lot of times, a short circuit in the board will cause it to fry. Other times, an electrical component will malfunction and cause strange behavior. Or if your furnace won’t turn on at all.

How to fix a circuit board that won’t turn on?

It will ensure there is no direct electricity supply in the PCB anymore. Start with the checking of the fuses of the circuit board. You can use nose pliers to pull out the fuse and check for its damage. Also, check the filament inside for a glass fuse. You will see a broken filament within a damaged fuse.