Furnace Pressure Switch Problems

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If you have a gas furnace, your pressure switch is an essential safety feature. But what does it do, how does it work and how can you tell if you have gas furnace pressure switch problems? Read on to find out.

What does a Pressure Switch Do?

Your furnace pressure switch has an important role – to ensure your furnace only runs if it is safe to do so. The pressure switch can be found close to the draft inducer motor, which is a motor driven fan designed to move harmful gases including carbon monoxide out of your home and get rid of poisonous gases from the previous heating cycle. If the venting air pressure is as desired, the pressure switch will allow the furnace to run, if not, it will shut down the ignition.  

How Do I Know If I Have Gas Furnace Pressure Switch Problems?

It is possible to test whether your furnace pressure switch is working using a multimeter.

This test is designed to determine whether the furnace pressure switch is closing when it should. 

  • Remove the pressure switch wires
  • Turn the furnace on
  • The draft inducer fan motor will begin to run
  • As air is pushed out of the vent, a vacuum is created which should cause the switch to close.
  • If the multimeter does not show any sign of change in continuity and the switch fails to close, this is a sign that your pressure switch is faulty.

Pressure Switch Replacement

Luckily, replacing a furnace pressure switch is a fairly easy furnace fix that doesn’t require special tools.

The first step is to find a replacement pressure switch. Lennox Pressure Switches and Carrier Pressure Switches are two popular furnace pressure switch brands, but it is best to purchase based on your furnace model number.

Here is a quick breakdown of the steps involved in replacing a gas furnace pressure switch once you have sourced your new part.

  • Be sure to turn off the power to the unit before you begin
  • Locate the pressure switch and disconnect the wires and hose from the switch.
  • If your new pressure switch has a bracket mounted already, remove the bracket and switch from the furnace together. If your new switch comes without a bracket, remove the switch from the bracket so the bracket can be re-used. 
  • Secure the new pressure switch in place in your furnace.
  • Reconnect the wires and hose to your new gas pressure switch.

Ready to get started on your gas pressure switch replacement? Find the furnace pressure switch parts you need including Lennox Pressure Switches and Carrier Pressure Switches, with Repair Clinic. Looking for a different brand or another furnace part? Simply type your furnace model number into our site to see related parts.


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