What the Blinking Lights on Your Furnace Mean

Woman technician checking furnace

Your furnace is a specialized piece of equipment with built-in methods of communication to let you or a service technician know there is something wrong. Like other appliances, flashing lights often indicate a problem. The make and model determines what these lights mean, so make sure you keep your copy of the system’s operating manual.

While many problems can be avoided with routine furnace maintenance in Queensbury, NY, Simons Heating & Cooling takes a step further. We’ve provided more information on common furnace errors and what these lights can mean. To schedule repairs, give us a call at (518) 535-1870 today.

Furnace Blinks Red Three Times

When your furnace is flashing a red light three times, there’s likely a specific error code. Here are a few possibilities:

  • Open limit switch: A limit switch is a safety device that prevents the furnace from overheating. If the limit switch is open, the furnace will shut down and display a three-flash error code.
  • Ignition problem: If the furnace is having trouble igniting, it may shut down and display a three-flash error code.

Furnace Blinks Four Times

If your furnace is blinking four times, it could indicate that there is an issue with the pressure switch. The pressure switch is a safety device that ensures proper airflow.

  • Blocked air filter: If the air filter is dirty or clogged, it can restrict the airflow to the furnace, causing the pressure switch to trip.
  • Ventilation blockage: The same goes for the vent pipe and ducts carrying combustion gases out of the furnace.
  • Leak: If there is a leak in the vent system, it can cause a drop in pressure and trip the switch.
  • Defective pressure switch: The pressure switch itself may be faulty and require replacement.

If you’re unsure of what’s causing the issue, it’s best to have a professional HVAC technician diagnose and repair the problem. Attempting furnace repair in Queensbury, NY, can be complex, and may be best handled by qualified professionals like Simons Heating & Cooling.

Furnace Lights Are Blinking Yellow or Green

While steady lights can indicate normal operation, blinking green or yellow lights may be signaling a problem.

  • Yellow: A yellow blinking light on your furnace may indicate that the furnace is in “normal” or “run” mode. This means that the furnace is functioning properly and providing heat to your home
  • Green: A green blinking light can indicate diagnostics mode or a problem with the furnace’s control board. Also known as the circuit board or control panel, it manages and regulates the furnace’s operation. This includes key systems like the ignition system, burners, blower motor and more.

It’s important to refer to your owner’s manual to determine the exact meaning. If you’re unsure or experiencing any other issues with your furnace, it’s best to contact Simons Heating & Cooling for assistance. Give us a call at (518) 535-1870 today.Top of Form