The pressure switch in a Goodman furnace ensures safe operation by verifying the inducer motor’s venting before ignition. When the Goodman furnace pressure switch is stuck closed, the furnace may short-cycle, fail to ignite, or operate unsafely. This article explains causes, diagnostic steps, repairs, cost considerations, and preventive maintenance to restore reliable operation.
| Symptom | Likely Cause | Recommended Action |
|---|---|---|
| Furnace won’t light | Switch stuck open or tubing blocked | Inspect tubing, vacuum ports, and inducer |
| Continuous fan or short cycling | Pressure switch stuck closed | Test switch for continuity; replace if failed |
| Error code 12/13 (pressure) | Pressure switch or inducer issue | Check inducer, venting, and switch |
Content Navigation
- What The Pressure Switch Does
- Why A Pressure Switch Gets Stuck Closed
- Safety First: Precautions Before Troubleshooting
- Tools And Materials Needed
- Step-By-Step Troubleshooting Guide
- 1. Observe Furnace Behavior And Error Codes
- 2. Inspect Pressure Tubing And Connections
- 3. Check Inducer Motor Operation
- 4. Test The Pressure Switch With A Multimeter
- 5. Use A Manometer To Verify Pressure Settings
- 6. Inspect For Backfeeding Or Wiring Faults
- 7. Replace The Pressure Switch If Confirmed Faulty
- How To Replace A Goodman Furnace Pressure Switch
- Costs And Time Estimates
- When To Call A Professional
- Common Diagnostic Pitfalls
- Preventive Maintenance To Avoid Future Pressure Switch Problems
- FAQ
- Additional Resources And References
What The Pressure Switch Does
The pressure switch monitors negative pressure created by the inducer motor to confirm proper venting before ignition. If the switch senses correct pressure, it closes a circuit to allow the furnace control board to proceed with ignition. If it cannot detect proper pressure, it remains open to prevent dangerous combustion.
Why A Pressure Switch Gets Stuck Closed
A pressure switch stuck closed is less common than one stuck open but can cause continuous operation or unsafe behavior. Common causes include mechanical failure, internal diaphragm rupture, electrical short, and misaligned or crimped tubing.
Mechanical Wear Or Diaphragm Failure
Over time the rubber diaphragm inside the pressure switch can weaken, tear, or become stuck to the housing. This can leave the switch permanently closed even if the inducer is off.
Electrical Issues
Wiring faults, corroded terminals, or a damaged control board can backfeed the pressure switch, reading it as closed. Moisture or condensation can accelerate corrosion and create unintended continuity.
Blocked Or Misrouted Tubing
If the pressure tubing is collapsed, kinked, or blocked by debris or rodents, the switch may not sense correct pressure changes. In some cases, the tubing collapse can create a stuck-closed reading under certain pressures.
Improper Installation Or Replacement
An incorrectly rated or installed replacement switch can have the wrong pressure setpoint, causing it to remain closed under normal conditions. Using OEM-specified parts reduces this risk.
Safety First: Precautions Before Troubleshooting
Before any diagnostic work, the furnace should be powered down at the breaker and the gas supply turned off if working near ignition components. Only qualified technicians should disconnect gas lines or replace combustion parts. Basic electrical and continuity checks can be done by skilled homeowners with proper tools.
Tools And Materials Needed
- Multimeter (with continuity and voltage)
- Manometer or digital pressure gauge (optional but helpful)
- Screwdrivers and nut drivers
- Shop vacuum and small brush
- Replacement pressure switch (OEM recommended)
- Replacement tubing and hose clamps
- Contact cleaner and electrical grease
Step-By-Step Troubleshooting Guide
1. Observe Furnace Behavior And Error Codes
Note any LED error codes on the control board or the user interface. Codes related to pressure or pressure switch faults narrow the issue quickly. Document the sequence of operation—whether the inducer runs and how long before fault.
2. Inspect Pressure Tubing And Connections
Visually examine the tubing from the inducer/vent to the pressure switch for kinks, pinches, or blockages. Remove tubing and blow through it to confirm airflow. Replace any brittle or collapsed tubing.
3. Check Inducer Motor Operation
Restore power and observe whether the inducer motor runs when the furnace calls for heat. If the inducer does not run, the pressure switch cannot detect proper pressure. Test inducer voltage with a multimeter and inspect capacitor and wiring.
4. Test The Pressure Switch With A Multimeter
With power off, disconnect the switch leads and check continuity across the switch terminals. A closed (continuity) reading with no inducer running indicates a stuck-closed switch. A switch that opens only when the inducer runs may be functioning correctly.
5. Use A Manometer To Verify Pressure Settings
Attach a manometer to the pressure port and observe the negative pressure. Compare readings to the furnace specifications. Incorrect pressure while the inducer runs suggests vent obstruction, inducer issues, or wrong switch rating.
6. Inspect For Backfeeding Or Wiring Faults
Check for voltage present at the switch when the furnace is off. If voltage is present, a wiring short or control board issue may be energizing the circuit and reading the switch as closed. Repair corroded connections and reterminate wires.
7. Replace The Pressure Switch If Confirmed Faulty
If diagnostics show the switch is stuck closed with no external cause, replace it with the correct OEM part. When replacing, ensure the new switch matches the original pressure rating and terminal configuration.
How To Replace A Goodman Furnace Pressure Switch
Replacement requires removing the old switch, installing new tubing if needed, and verifying operation. Steps: power off, label wires, remove terminals, transfer tubing, mount new switch, reconnect, power up, and test.
- Turn off power at breaker and shut gas supply if applicable.
- Label or photograph wire connections for reassembly.
- Loosen clamps and remove tubing from the old switch.
- Remove mounting screws and swap the switch with the new unit.
- Reattach tubing and secure with clamps; install new tubing if brittle.
- Reconnect wires, restore power, and run a furnace cycle to confirm proper operation.
Costs And Time Estimates
For homeowners, a pressure switch replacement by a HVAC technician typically ranges from $150 to $350, depending on part cost and service fees. DIY-minded individuals may spend $30–$80 for the part and an hour or two of time.
When To Call A Professional
Contact a licensed HVAC technician when the issue involves gas components, if the inducer motor is malfunctioning, or when control board faults are suspected. Professionals should handle complex electrical diagnostics and combustion safety checks.
Common Diagnostic Pitfalls
- Replacing the switch without checking tubing or inducer first can lead to repeat failures.
- Using non-OEM switches with incorrect pressure ratings causes improper operation.
- Failing to check for wiring shorts and control board backfeed may result in misdiagnosis.
Preventive Maintenance To Avoid Future Pressure Switch Problems
Regular maintenance reduces the chance of switch failure. Key actions include annual furnace tune-ups, cleaning the inducer and venting paths, replacing brittle tubing, and checking electrical connections for corrosion.
Recommended Maintenance Checklist
- Annual professional inspection and cleaning of inducer and flue paths.
- Replace pressure tubing every few years or when brittle.
- Keep intake and exhaust vents clear of debris and nesting materials.
- Monitor furnace error codes and address small issues promptly.
FAQ
Can A Pressure Switch Cause The Fan To Run Constantly?
Yes. If the pressure switch is stuck closed it can signal the control board incorrectly, causing continuous operation or improper cycling. Full diagnostics should confirm the root cause.
Is It Safe To Tape Or Temporarily Bypass The Pressure Switch?
No. Bypassing a pressure switch disables a critical safety device and risks unsafe combustion. Temporary bypasses are dangerous and illegal; only proper repairs should be performed.
How Long Does A Pressure Switch Last?
Pressure switch lifespan varies with usage and environment but typically lasts many years. Exposure to moisture, corrosion, and mechanical stress reduces lifespan and increases failure risk.
Additional Resources And References
For model-specific information consult the Goodman furnace manual, the manufacturer’s technical bulletins, and HVAC trade guides. OEM part numbers ensure correct replacements and compatibility.
Key Takeaway: A Goodman furnace pressure switch stuck closed requires systematic troubleshooting—inspect tubing and inducer, test switch with a multimeter and manometer, check electrical wiring, and replace the switch with the correct OEM part when confirmed faulty. Seek professional help for gas-related or complex electrical issues.
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