Here's What Happens When a Furnace Pressure Switch Goes Bad

Inland Empire Comfort
April 20, 2023

Pressure switches are safety features that control your furnace's power supply. If your pressure switch fails, your furnace won't work. You should understand what happens when a furnace pressure switch goes bad so you can keep your furnace operational.


Learn the signs and causes of a broken pressure switch and how Riverside's reliable heater repair experts can help you fix it. Our team at Inland Empire Comfort can provide the service you need; just call us at (951) 336-1892.


Types of Pressure Switches

Pressure switches either use electricity or manual force to operate. They automatically power down your furnace's heating process when they detect negative pressure.


This feature is important, as it prevents exhaust fumes from blowing back into the furnace and starting fires. Pressure switches also help with energy efficiency.


Some furnaces have more than one pressure switch. For instance, two-stage furnaces use two pressure switches, one for high pressure and another for low-pressure. However, both single-stage furnaces and condensing units only have one pressure switch.


Signs of a Broken Pressure Switch

Common signs that your furnace's pressure switch isn't working include the following:


  • Frequent unit shutdowns: If your furnace constantly turns on and off, you might have a faulty pressure switch.
  • Inefficiency: Furnaces with broken pressure switches often struggle to work, even if you turn them on.
  • Lack of hot air: Are your vents producing hot or warm air? Furnaces with broken pressure switches often struggle with providing hot air.


Why Did My Pressure Switch Break?

You're probably still asking, "What happens when a furnace pressure switch goes bad?" Pressure switches break for many different reasons. One of the most common pressure switch problems is frequent usage.


Pressure switches wear down, especially after constant usage. In particular, electrical switches rely on different components and wires, each of which deteriorates over time. If you have a manual pressure switch, it can still break after repeated use. 


Here are other some other reasons why pressure switches break:


  • Damaged hoses: Pressure switches rely on hoses to handle exhaust fumes. If these hoses rupture, crack, or become loose, they might cause your switch to malfunction.
  • Dirty or water-filled hoses: Sometimes, pressure switch hoses become clogged with dirt, debris, and water. 
  • Damaged diaphragms: When working correctly, the pressure switch diaphragm handles a switch's air supply. However, diaphragms can crack or suffer perforations, causing the entire switch to fail. 


How to Fix a Pressure Switch

You should first test your pressure switch before attempting any repairs. Simply turn your furnace off, then inspect the switch hoses, hose port, furnace cover, and ventilation pipes. Watch for dust, debris, water, visible damage, and other tell-tale signs of pressure switch issues.


Professional Furnace Repair Services in Riverside, CA

Are you wondering, "What happens when a furnace pressure switch goes bad?" Our team at Inland Empire Comfort has you covered!


We provide expert furnace repairs throughout the Riverside area. Homeowners love our reliable, fast service and count on us to fix their furnace issues.


Call us at (951) 336-1892 for a quote for furnace repair or heating installation in Riverside, CA.

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