Furnace Pressure Switch Stuck Open: Troubleshooting & DIY Fixes

If you are experiencing a furnace pressure switch stuck open scenario, it needs immediate attention and resolution. The furnace pressure switch is a safety device that detects when the furnace pressure is too high and automatically shuts off the furnace. If the pressure switch is not fixed immediately, it could result in serious injury or death.

Your furnace pressure switch being stuck open could be due to disturbance in the vent, dysfunctional pressure switch, and broken or disconnected pressure switch hose. We will start with defining a furnace pressure switch and then discuss the causes of the problem with solutions.

What is Furnace Pressure Switch? - Furnace Pressure Switch Stuck Open

A furnace pressure switch is a safety device used in homes to turn off the gas and electric to the furnace when the pressure in the furnace reaches a certain level. The pressure switch monitors the pressure in the furnace and turns off the power when it reaches a safe level. This prevents the gas and electric from being turned on until the furnace has cooled down.

When a furnace is running, the heat from the furnace can cause air to flow into the furnace. The air flow is called backdrafting. The pressure switch prevents backdrafting by closing off the exhaust pipe when the furnace temperature gets too high. 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. After being shut off by the furnace pressure switch, the furnace will typically start up again within a few minutes due to the heat of the burning gas.

If the issues remain and aggravate, the furnace pressure switch shuts off. The motor may run for a few seconds and then shut off, indicating that something went wrong. In some cases, the pilot light may stay on even after the furnace pressure switch shuts off.

The furnace pressure switch generally stays in an Open position. At its optimum capacity, this 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.

Causes and Solutions for a Pressure Switch Stuck Open - Furnace Pressure Switch Stuck Open

  1. Disturbance in Vent - Causes and Solutions for a Pressure Switch Stuck Open

    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 - Causes and Solutions for a Pressure Switch Stuck Open

    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 - Causes and Solutions for a Pressure Switch Stuck Open

    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 Solutions - Causes and Solutions for a Pressure Switch Stuck Open

  • 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.

Conclusion - Furnace Pressure Switch Stuck Open

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.

Related Articles You May Like