Furnace Pressure Switch Problems: Common Errors, Causes, and Fixes

The furnace’s pressure switch is a critical safety mechanism. If it detects insufficient draft pressure, it can prevent ignition or shut down burner operation. Understanding basic pressure switch troubleshooting helps you identify simple issues and know when to contact Central Oregon Heating, Cooling, Plumbing & Electrical.

What Is a Furnace Pressure Switch?

A furnace pressure switch is a safety device that verifies that there is adequate venting before it allows the furnace’s ignition to happen. When your furnace calls for heat, the draft inducer fan starts and creates a slight vacuum. The pressure switch senses the negative pressure and closes, signaling the furnace’s control board to ignite the burners.

The furnace pressure switch is an important safety component that helps verify proper draft conditions before ignition and during operation. If the required pressure conditions aren’t met, the furnace may prevent ignition or shut down the burners. Because pressure switch faults can indicate venting or combustion-related problems, recurring errors require professional inspection.

Signs of Furnace Pressure Switch Problems

If you notice the following bad furnace pressure switch symptoms, you should reach out to our team for furnace repairs in Bend, OR.

• The furnace refuses to ignite.
• Your inducer motor runs, but the burners won’t ignite.
• You have no heat or intermittent heat issues.
• The furnace starts, then shuts down.
• There are repeated startup attempts.
• A furnace pressure switch error code appears on the display.
• The furnace is in lockout mode.

Common Furnace Pressure Switch Error Codes

As part of your pressure switch troubleshooting, check the display for common error codes to narrow down the list of possible issues that may be involved.

Pressure Switch Stuck Open

This code means that the draft is unverified and the pressure switch is open. It can occur due to blocked venting or exhaust pipes, damaged pressure tubing, furnace inducer motor problems, condensate drainage restrictions, or a faulty pressure switch.

Pressure Switch Stuck Closed

If the pressure switch is closed before the inducer motor turns on, this code will appear. It may be due to stuck switch contacts, wiring issues, control board malfunctions, or electrical problems. Because electrical and safety systems are involved, you should schedule professional diagnostics.

Pressure Switch Not Closing

Insufficient draft pressure, ventilation and drainage restrictions, and inducer-related problems can result in the furnace pressure switch not closing. Error codes vary between models and manufacturers, so always consult your manufacturer’s guide.

Common Causes of Furnace Pressure Switch Problems

Pressure switch errors can result from the following issues, not just failed switches.

• Blocked furnace exhaust or intake vent
• Malfunctioning inducer motor
• Clogged condensate drain or trap
• Control board malfunctions
• Excess moisture in the pressure tubing
• Restricted or improper venting
• Faulty electrical connections
• Component wear 
• Damaged pressure switch tubing

Furnace Pressure Switch Troubleshooting: Safe Checks Homeowners Can Try

As part of your HVAC troubleshooting, you can perform the following steps. 

• Verify the thermostat settings and power availability.
• Check the circuit breaker.
• Inspect the filter.
• Check for blockages in the exterior intake and exhaust openings if it’s safe to do so.
• Look for visible error codes.
• See if the inducer motor starts.
• Note which issues occur and when.

Important Safety Note: You should never bypass the pressure switch, open sealed combustion components, test electrical systems, disconnect pressure tubing, or repeatedly reset a furnace that shows safety-related faults.

Furnace Pressure Switch Troubleshooting Guide

This guide covers common symptoms, causes, homeowner checks, and when to call a technician.

How HVAC Technicians Diagnose Furnace Pressure Switch Problems

When you reach out for furnace repairs in Redmond, OR, our team will quickly work to inspect your intake venting, exhaust venting, wiring, furnace controls, pressure switch tubing, inducer motor operation, and condensate drainage. We’ll check the furnace error codes, measure draft pressure, and test the pressure switch’s operation. Our team will explain your repair options after identifying the cause.

Can You Reset a Furnace Pressure Switch?

A furnace pressure switch typically opens and closes automatically in response to changes in draft pressure and does not have a manual reset button. The furnace control board may automatically retry the ignition sequence after certain faults. Because of the risk of CO poisoning and house fires, you should never bypass safety switches.

Furnace Pressure Switch Repair vs. Replacement

Deciding whether to repair or replace the furnace switch depends on the underlying cause of the issue. A professional diagnosis can determine if you need to resolve drainage issues, correct venting to fix the draft pressure, repair damaged pressure tubing, or replace the pressure switch. Replacing the switch only makes sense if the switch is the underlying cause.

Can a Bad Furnace Pressure Switch Prevent Heating?

A pressure switch fault interrupts the ignition sequence, stopping the burners from igniting. Recurring faults lead to furnace lockouts. Other issues can cause similar symptoms, making professional diagnosis essential.

When to Call an HVAC Professional

You should immediately stop using your furnace if you suspect a serious combustion or venting safety issue. Professional repairs are also necessary in the following situations.

• Your furnace won’t ignite.
• The pressure switch error keeps coming back.
• You experience repeated furnace lockouts.
• The condensate drainage is blocked.
• There may be a blocked exhaust or intake vent.
• The inducer motor runs, but the burners don’t ignite.
• The pressure switch tubing is damaged.
• There are unusual furnace noises.
• Your furnace shuts down repeatedly.
• You suspect CO, combustion, or venting issues.

How to Prevent Furnace Pressure Switch Problems

To avoid future issues, remember to perform the following maintenance tasks.

• Schedule a furnace tune-up each fall.
• Replace the air filter on schedule.
• Remove obstructions from exterior intake and exhaust openings.
• Address condensate drainage problems promptly.
• Have a technician inspect inducer operation, venting, and pressure switch components.
• Schedule service for recurring furnace error codes.

Why Furnace Pressure Switch Problems Can Occur During Central Oregon Winters

The cold winter temperatures in Bend and Redmond lead to longer furnace operating periods and snow buildup around exterior vent openings, which can lead to pressure switch issues. Similarly, seasonal debris around vent openings and condensate drainage issues due to freezing weather can cause problems. Through fall furnace maintenance, you can detect minor problems before they escalate.

Why Homeowners in Bend & Redmond Trust Central Oregon Heating, Cooling, Plumbing & Electrical

Central Oregon can help with your furnace-related issues. Our experienced technicians offer pressure switch and inducer system troubleshooting, thorough furnace diagnostics, and clear repair recommendations. When a problem occurs, our heating services are readily available throughout Bend, Redmond, and surrounding Central Oregon communities.

Frequently Asked Questions About Furnace Pressure Switches

What does a furnace pressure switch do?

The furnace pressure switch verifies adequate draft pressure before ignition and monitors that pressure during burner operation. If the required pressure isn’t maintained, it can interrupt burner operation to help protect against unsafe venting conditions.

What causes a furnace pressure switch to stay open?

A furnace pressure switch may be stuck open due to obstructed venting, a blocked condensate drain, damaged tubing, a weak or dirty inducer motor, or a faulty switch. Because the cause can vary, it’s important to call an HVAC technician for help with furnace pressure switch troubleshooting.

What does a pressure switch stuck closed error mean?

When there is an error message that says the furnace pressure switch is stuck closed, it means that the pressure switch remains closed when there is no draft pressure present. If the system senses a closed pressure switch when the system is idle, it may prevent ignition and display a fault code. 

To fix the problem, you must diagnose and resolve the underlying cause. For example, a pressure switch stuck-closed error may result from stuck switch contacts, electrical shorts, control board problems, or an abnormal pressure condition.

How do I know if my furnace pressure switch is bad?

A furnace that won’t ignite, repeatedly enters lockout, or displays pressure switch error codes may have a pressure switch-related problem. However, blocked venting, condensate restrictions, and inducer motor faults can produce similar symptoms. An HVAC technician can test the switch and related components to determine whether replacement is necessary.

Can a clogged furnace vent cause a pressure switch error?

Absolutely. Clogged furnace vents can interfere with proper draft and prevent the pressure switch from detecting the required pressure differential.

Can a furnace run with a faulty pressure switch?

A furnace pressure switch failure will generally stop the furnace from operating properly. If the furnace has a switch that is stuck closed, it won’t turn on. Meanwhile, a switch that remains open when it should close can prevent ignition, cause a safety lockout, or trigger an error code.

Can I reset a furnace pressure switch?

Most furnace pressure switches reset automatically when the required draft conditions return. They generally don’t have a homeowner-operated reset button. Restarting the furnace may temporarily clear some fault indications, but it won’t correct blocked venting, inducer problems, or a faulty switch. Avoid repeated resets and schedule professional service if the error returns.

Why is my inducer motor running but my furnace not igniting?

If your furnace is not igniting, it may be due to a faulty pressure switch or one that fails to close when the inducer motor starts. Other issues, such as a clogged condensate drain or blocked pressure switch tubing, can cause this problem. The furnace may fail to ignite if something is wrong with the igniter or control board.

Should I replace my furnace pressure switch if I get an error code?

Not necessarily. While the error code can happen because the pressure switch is malfunctioning, it can also occur due to clogged drains, blocked vent pipes, inducer motor problems, or other issues. The only way to keep the error code from recurring is by fixing the underlying cause.

How much does furnace pressure switch replacement cost?

It depends on the furnace model and the presence of other problems. The best way to find out is by scheduling furnace repairs in Bend, OR. Our team will evaluate your system and provide an upfront, no-obligation estimate, so you know exactly what to expect.

Schedule Furnace Repair in Bend & Redmond

If basic pressure switch troubleshooting doesn’t fix your furnace issues, Central Oregon Heating, Cooling, Plumbing & Electrical can help. We can run diagnostics on your inducer motor, ignition, and pressure switch. Our team can also inspect your venting and condensate drainage for blockages.

Don’t ignore recurring furnace pressure switch error codes. The pressure switch is an important safety feature, so any error codes should be professionally inspected and resolved. Schedule your professional furnace troubleshooting in Bend or Redmond today.