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How A Pressure Switch Problem Can Keep Your Furnace From Running

The furnace pressure switch in your furnace is a vital part of its safety system.

Yet when this switch stops working the way it should, it can keep even a perfectly safe furnace from functioning.

If you would like to improve your knowledge of this important component, then read on.

This article will discuss the role of the furnace pressure switch, and the unintended problems it can cause.

Safe Venting

The purpose of this pressure switch is to ensure that the draft motor is running before it allows gas to flow into the combustion chamber.

The draft motor is responsible for pushing toxic exhaust byproducts out of your home through the vent pipe.

When the draft motor is on, it creates a vacuum that sucks a rubber diaphragm on the pressure switch inward, which in turn triggers a switch on the gas valve, allowing gas to move through.

Unless the furnace pressure switch detects a vacuum, it will not allow gas to enter the combustion chamber.


Almost all furnace pressure switch problems involve a failure to trigger the gas valve to open, even when the necessary vacuum is present.

This is usually due to a:

  • Diaphragm that has become physically damaged, or
  • Physical blockage within the pressure switch

In such cases, you’ll need an HVAC technician to either repair or replace the existing furnace pressure switch.


If you believe that your furnace pressure switch may be keeping your furnace from running, then give the professionals at Metro Heating & Cooling a call at (651) 294-7798 your earliest convenience.

We cover Blaine, Bloomington, Brooklyn Park, Eagan, Edina, Hastings, Maplewood, Minneapolis, Minnetonka, Roseville, North Saint Paul, Saint Paul, Saint Paul Park, South Saint Paul, Stillwater, West Lakeland, West Saint Paul, White Bear Lake, Woodbury, and many more locations.

Can’t find your town listed? Contact us at (651) 294-7798 to tell us where you live, so we can help you.

Schedule a HVAC repair anywhere in the Minneapolis or St. Paul area today by calling (651) 294-7798 or by requesting an estimate online.


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1220 Cope Avenue East, Maplewood, MN 55109