Furnace Pressure Switch Stuck Open: Troubleshooting & DIY Fixes

Furnace Pressure Switch Stuck Open

If you are experiencing a furnace pressure switch stuck open scenario, it needs immediate attention and resolution. This could be due to disturbance in the vent, dysfunctional pressure switch, and broken or disconnected pressure switch hose.

We will start with a furnace pressure switch and then discuss the causes of the problem with solutions.

What is Furnace Pressure Switch?

A furnace pressure switch monitors and manages building pressure within the system. It generally stays in an Open position. The pressure switch ensures ventilation of combustion gases during the operation of the furnace.

Furnace pressure switch prevents back drafting, a process where combustion gases can re-enter your home and affects air supply. This situation can also lead to minor blasts within the heat exchanger, a core part of any furnace.

The pressure switch observes a draft inducer that filters out gases from the heat exchanger and throws them out of your home. If the issues remain and aggravate, close the system for a couple of minutes and re-start the system.

At its optimum capacity, an open furnace pressure switch ensures safety features and healthy indoor air. If it shows an error and is stuck open, it could be due to a problem with the switch or any other part of the machine.

Furnace Pressure Switch Stuck Open: Causes And Solutions

1.Disturbance in Vent

The pressure switch stays open when the fuel pipe gets blocked or obstructed. The blocked pipe could not exit combustion gases, and it could be hazardous for you and your family. Fuel pipe blockage could be due to accumulated debris such as feathers, leaves, dust, etc.

Check your fuel pipe and if found blockage because of debris, simply clean it. Switch off the system, clean the pipe, and switch on the machine to solve the problem. If the problem still exists, it is advisable to contact a technician for professional help.

The location of the fuel pipe could be on the terrace or roof or a white PVC pipe on the sides of the house.

2. Broken or Disconnected Hose

The pressure switch monitors the induced motor and ensures its proper functioning through the hose. If this hose breaks or is disconnected, the pressure switch cannot work properly. It will give inaccurate data and be stuck open.

It is easy to detach and repair the hose by yourself. Customers can easily take care of it if feels confident about it. But it is advisable to contact expert help for better diagnosis and advanced help. They can even replace the hose if the damage is beyond repair.

3. Dysfunctional Pressure Switch

If there is nothing wrong with the hose and the fuel pipe is clear, you should check the pressure switch itself. You can try repairs by yourself, but you should consult for professional support to eliminate the probability of errors. 

An authorized technician will check the pressure switch with a digital multimeter. They can replace the switch if required.

Other Causes and Solution

  • Your system might experience a temporary pressure switch stuck situation because the blower fan does not turn off. To resolve, just sweep off a wire from the pressure switch and see if the blower fan turns on or not. If a problem exists, consider replacing the switch. Always buy a furnace pressure switch from a reliable OEM.
  • A blocked condensate drain can also cause a problem with the pressure switch. Around ninety percent of the furnaces are equipped with a condensate drain. Try cleaning yourself. If required, there are always professional technicians for help.


We have explained prominent reasons for the furnace pressure switch being stuck open. You can try yourself and resolve these issues. If feeling confused, consult a certified technician or HVAC product supplier, they will visit and diagnose the exact problem. They can also replace the switch, hose, and even unit if required and you authorize.

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