What Is The Pressure Switch On My Furnace?

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What Is The Pressure Switch On My Furnace?

Some of the components of a traditional furnace likely sound familiar, including heat exchanger, burner, pilot light, ignition switch, etc. One part that may not is a furnace pressure switch. But make no mistake about it, unfamiliarity doesn’t mean unimportance. The furnace pressure switch is an important safety feature that your friends at Masters Heating & Cooling Inc. want our customers to be aware of. 


Here are some things to know about a furnace pressure switch:

  1. Function. Located near the furnace motor, the pressure switch is an automatic safety control that will shut off the furnace if it detects negative pressure produced by the draft inducer motor, which can lead to dangerous exhaust fumes being sucked back into and circulated throughout your home. The switch is also a safeguard against gas leaks and will also shut down the furnace in the event of a mechanical failure.
  2. Potential Problems. These issues can cause the switch to trip or just plain fail, which can lead to furnace malfunctions.
  • Wear and tear. If your furnace is getting up there in years, the components are too, and an old pressure switch can cause faulty readings and cycling.
  • Issues with the switch casing itself, including holes or tears.
  • Dust buildup that can cause the switch to jam, get stuck open or close or break.


Some minor troubleshooting can be done to determine if the pressure switch is jammed and inoperative. First, make sure you turn off the power to the furnace, either via a switch near the furnace or at the breaker box:

  • Remove the main access panel to the furnace and inspect the pressure switch itself and the hoses/connections. Make sure the hoses are unobstructed and firmly connected. Make sure electrical wires are secure, not frayed and firmly connected to the switch terminals.
  • Make sure the furnace cover and vents are clear of debris. Your furnace needs air to operate correctly. If the air intake vents are blocked or there are other air circulation obstructions, this could cause the switch to trip.


The furnace pressure switch is a crucial mechanical component that can affect not only the furnace’s operation, but the safety of your family. If the minor troubleshooting outlined above does not solve the issue, it’s time to call the HVAC professionals at Masters. Our licensed technicians are trained in all aspects of furnace operation and will be able to diagnose a faulty furnace pressure switch immediately. Even more important, they will fix the problem correctly, ensuring that your furnace is functioning correctly and safely. For our customers’ convenience, we also offer our Energy Savings Agreement (ESA) maintenance plan. The ESA leaves the scheduling to us and includes an annual 17-point furnace inspection and tune-up. Give us a call today for more information and please follow us on social media.