Furnace Pressure Switch Stuck Open? Here Is What to Do

furnace pressure switch stuck open

Is your furnace pressure switch stuck open? There are many reasons this can happen, but the good news is that you can troubleshoot it. The burner and blower won't work effectively when the pressure switch does not work due to an incomplete electric circuit.

When repairing a furnace pressure switch stuck open, begin by inspecting the pressure switch to know why it stuck open. Also, check for clogs in the vents, inspect the hose tube and clean the drain line to ensure the proper functioning of your system.

Opening the HVAC and inspecting it can be tricky for homeowners without expertise. To avoid more damage to your system, contact an HVAC expert. Before looking at how to troubleshoot a stuck pressure switch, we will first look at the reasons they get stuck.

Without further ado, let us get started.

What Is A Furnace Pressure Switch?

The furnace's pressure switch is a safety device for your furnace and home. This part of the furnace is near the draft inducer motor, which exits combustion gases from the furnace up the vents.

When you switch on the machine, the motor starts running first to create a negative pressure to suck harmful gases out of the furnace. Once you switch on the device, the pressure switch senses the negative pressure and closes to complete the electric circuit, switching on the furnace burner and heat blower.

Without the negative pressure, no negative pressure will affect how the system works. The low negative pressure also causes the switch to remain open, meaning no circuit completion, so the furnace burner cannot start.

Reasons Your Pressure Switch Stuck Open

Although the furnace pressure switch has a crucial role in the system, it can sometimes stick open. So before calling an HVAC expert, check for the following.

     1. Blockage In The Exhaust Vent

Blockage of furnace exhaust vents is a leading reason your pressure switch is stuck open. It causes the furnace not to run entirely or shuts it down. Some causes of blockage in the vent are bird nests, debris, dust, branches, and snow.

If this is the reason your pressure switch cannot close, clean the vents. Check where the exhaust vent exits your home to see if there is snow, debris, and bird nests. Once you remove and clean the area, check if the switch is working correctly.

     2. Loose Wire Connection

Another cause of faulty pressure switches is loose wires. A disconnection or a lousy connection will leave the electric circuit incomplete, meaning there is no power flow. When it happens, the circuit won't close.

     3. Malfunctioning Suction Tube

The pressure switch detects the negative pressure at the suction tube. If the tube is not working correctly, the switch won't be able to detect the pressure, and it will remain open.

     4. Damaged Switch

How old is your Furnace machine? The reason your pressure switch is not closing could be due to wear and tear. If your furnace does not require replacement, you can replace the pressure switch only.

     5. Furnace Lockout

If there is a repeated break in the ignition sequence, the Integrated Furnace Control can lockout the unit. The repeated break in the ignition sequence happens primarily due to overheating or a non-functioning thermostat.

Troubleshooting A Pressure Switch Stuck Open on Furnace

Realizing that your pressure switch is not working can be stressful. However, many homeowners experience this problem, which is easy and quick to correct.

Before thinking about calling an HVAC expert;

     1. Inspect The Pressure Switch

The leading reason your furnace pressure switches stuck open is the blockage of the fluent vent. First, inspect it to see if there is debris, dirt, bird nests, and leaves. You should also check for snow and soot build-up.

If you see any signs of dirt, clean the vent and test if the switch is working. You won't need an HVAC expert if you can successfully clean the area. However, you can hire a technician if you want a thorough job.

     2. Check The Vents

Blockage in the venting can also lead to a stuck pressure switch. Check the chimney down to the other vents for any blockage. Next, inspect the vent pipe that runs through the wall and clean it. Once the venting system is clean, run the unit to see if it works.

     3. Inspect The Suction Tube And Drain Line

When there is a poor connection of the hose to the furnace, the pressure switch won't function properly. Always ensure it is tightly connected and is clean from debris. Also, remove any debris that could cause blockage around it.

Check if the drain line is functioning well, and remove any dust and dirt that could cause blockage. Finally, wipe any water collected on the drain pan and ensure proper drainage.

     4. Inspect The Inducer Motor

If the reason your pressure switch stuck open is not due to blockage, it could be having a faulty inducer motor. You need a technician to check if the motor works correctly to ensure the furnace's efficiency.

The inducer motor could fail due to wear and tear or clogging. If you cannot clean the part and make the motor work, you must replace it. Again, work with an expert who will advise you on buying the best parts.

     5. Hire An Expert

The last resort to troubleshooting your stuck pressure switch should be calling an expert. They will inspect the switch, the areas around it, and the entire furnace to see the problem. If your furnace is too old, you could require a replacement.

You can also start by calling an expert to inspect your furnace. It is advisable to let the experts work on these systems to avoid causing more trouble and leading to expensive repairs and replacements.

When hiring an HVAC expert, ensure they are licensed and insured. A license is a significant certificate showing the person can handle your machine. An insurance company will compensate you if damages happen to your furnace during the repair.

Final Words

Troubleshooting your HVAC when the furnace pressure switch is stuck open is fast and straightforward. Start by finding why the switch is not closing, and clean all the blocked parts. Call an expert to fix the issue if unblocking the vents and drain pipe does not work.

Contact Hurliman today for reliable furnace installation and repair services.