Goodman Furnace Pressure Switch Location and How to Find It

The Goodman furnace pressure switch is a small but essential safety device that ensures proper venting and combustion. Locating and testing the pressure switch can help diagnose common fault codes, no-heat conditions, or persistent lockouts. This article explains where to find the pressure switch on Goodman furnaces, how it works, how to test and replace it safely, and troubleshooting tips for homeowners and HVAC technicians.

Furnace Type	Typical Pressure Switch Location	Notes
Upflow/Downflow Cabinet	Near Inducer Motor On Side Or Front Panel	Accessible after removing service panel
Horizontal (Mid-Efficiency)	Near Combustion Chamber Or Flue Collar	May be tucked beside pressure tubing
High-Efficiency Condensing	Close To Draft Inducer And Exhaust Venting	Often visible behind blower assembly

What The Goodman Furnace Pressure Switch Does

The pressure switch is a safety interlock that verifies the inducer motor creates the correct draft before the furnace fires the ignition. It senses negative or positive air pressure via a small rubber hose connected to the inducer housing or vent. If the switch does not close when required, the control board prevents ignition and often displays a diagnostic code or LED blink pattern.

Key Function: Prevents gas ignition if exhaust gases cannot vent properly, protecting the home and furnace from dangerous conditions.

Common Pressure Switch Locations On Goodman Furnaces

Goodman furnace pressure switch location varies by model and installation orientation. The most common places to look include the inducer assembly, the side or front of the combustion compartment, and near the flue collar. Identifying visual cues helps locate the switch quickly.

Near The Inducer Motor

Most Goodman furnaces mount the pressure switch directly on or adjacent to the inducer motor housing. Look for a round or rectangular device with one or two small vacuum hoses attached and two electrical terminals or spade connectors.

On The Side Of The Combustion Chamber

Some models place the pressure switch on the side panel of the combustion chamber. It may be tucked behind wiring or insulation and requires removing the front service panel to access.

Close To The Vent Or Flue Collar

On horizontal or compact configurations, the pressure switch can be near the flue collar where the vent attaches. Follow the pressure tubing from the inducer or vent to the component to confirm its location.

How To Identify The Pressure Switch Visually

The pressure switch usually has a circular diaphragm housing or small rectangular box with a vacuum port for the tubing. Two metal terminals are visible for the control board wiring. Labels may include pressure ratings in inches of water column (e.g., 0.60″ WC).

Visual Checklist: vacuum hose attached, two electrical spade terminals, small stamped rating, mounted with screws or bracket.

Tools And Safety Precautions Before Inspecting

Safety is critical when working around gas and electrical components. Turn off power to the furnace at the switch and the breaker. If the unit is gas-fired, consider shutting off the gas supply for extra precaution. Use insulated tools and wear safety glasses and gloves.

Recommended tools: multimeter, small mirror or flashlight, insulated nut drivers, needle-nose pliers, replacement pressure tubing, and a service manual or model sticker for reference.

Step-By-Step Guide To Locate The Pressure Switch

1. Turn Off Power And Gas: Switch off the furnace power and close the gas valve if necessary.2. Remove The Access Panels: Unscrew the front service panel; some models have multiple panels.3. Find The Inducer Motor: Locate the round inducer assembly near the flue outlet.4. Trace The Small Rubber Tube: Follow the small vacuum hose from the inducer housing or flue area; it leads directly to the pressure switch.5. Identify The Switch: Confirm the device with two terminals and a vacuum port; label will often list pressure rating.

How To Test A Goodman Furnace Pressure Switch

Testing can confirm whether the switch is passing or failing. Testing requires knowledge of multimeter use and safe operation of the furnace inducer motor.

Continuity Test With Power Off

Disconnect power. Remove the pressure switch wires. Set the multimeter to continuity or ohms. Connect probes to the two terminals. With the switch at rest (inducer off), many switches read open. When the inducer runs and correct pressure is present, the switch should close and show continuity.

Live Voltage/Closure Test With Inducer On

Restore power and start the furnace to the call-for-heat stage until the inducer motor runs. Carefully measure across the switch terminals: a closing action should show near zero ohms or continuity when the inducer has reached proper draft. Use caution to avoid live contact with other components.

Using A Manometer

A manometer measures the pressure across the switch and verifies the switch’s rated range. Connect manometer tubing to the switch vacuum port and observe whether it reaches the specified inches of water column. Compare readings to the switch label.

Common Pressure Switch Problems And Symptoms

Symptoms of a faulty or mislocated pressure switch include furnace lockouts, blinking error codes, the inducer running but no ignition, and intermittent heating. Several issues can cause these symptoms besides a bad switch.

• Blocked venting or condensate traps causing improper draft
• Cracked or collapsed vacuum tubing leaking pressure
• Misadjusted or failing inducer motor
• Air leaks in the combustion chamber or duct connection
• Faulty pressure switch contacts or diaphragm

Troubleshooting Steps For Pressure Switch Issues

1. Inspect Tubing For Cracks Or Disconnections: Replace brittle vacuum hose with high-temperature tubing if damaged.2. Check Venting For Obstructions: Bird nests, debris, or crushed PVC can restrict flow.3. Test Inducer Motor Performance: Ensure the inducer spins freely and reaches operating speed.4. Verify Condensate Trap: High-efficiency furnaces collect condensate — a clogged trap can block pressure sensing.5. Swap Or Test The Switch: If all else checks out, bench-test or replace the switch to confirm proper operation.

Replacing The Goodman Furnace Pressure Switch

Replacing a pressure switch is straightforward but requires correct part selection. Match the replacement switch by part number, pressure rating, and terminal style. Installing the wrong rating may allow unsafe operation or continuous faults.

Steps: Turn off power and gas, remove wires and tubing, unmount the switch, install the new switch in the same orientation, reconnect tubing and wires, and restore power. Run the furnace through a cycle to confirm proper operation.

When To Call A Professional HVAC Technician

If venting repairs, gas valve service, inducer motor replacement, or complicated diagnostics are required, call a licensed HVAC technician. Working with gas components can be dangerous and may violate codes if not performed by a qualified professional.

Hire A Pro If: the inducer motor needs replacement, gas valve or ignition issues exist, or the diagnosis remains unclear after basic troubleshooting.

Model-Specific Notes For Goodman Furnaces

Different Goodman lines (GMS8, GMVC, GMSS, etc.) use similar pressure switch designs but may vary in placement. Always consult the furnace schematic on the unit door or the Goodman service manual for model-specific wiring and pressure requirements.

Tip: The model/serial sticker on the furnace cabinet helps locate the correct manual online for accurate diagnostics and part numbers.

Preventive Maintenance To Avoid Pressure Switch Failures

Regular maintenance reduces pressure switch failures. Replace air filters on schedule, keep vent terminations clear, inspect pressure tubing during annual service, and ensure the inducer motor is lubricated and unobstructed.

• Annual inspection by an HVAC pro
• Replace vacuum tubing every few years if it shows aging
• Clean condensate traps and vent elbows

Helpful Resources And References

Goodman service manuals, manufacturer schematics, and HVAC troubleshooting guides provide authoritative information. Online forums and HVAC training sites offer step-by-step videos for locating and testing pressure switches on specific models.

Goodman Manufacturing Official Site provides manuals and technical bulletins. Local utility and safety agencies also offer guidance on gas appliance safety.

Quick Checklist For Locating And Verifying The Pressure Switch

Before You Start: Power Off, Gas Off, Tools Ready.1. Remove access panels.2. Find the inducer motor.3. Follow the vacuum hose to the switch.4. Inspect tubing and connections.5. Test continuity with multimeter.6. Measure pressure with manometer if available.7. Replace switch only after verifying all vent and inducer issues are resolved.

Locating the Goodman furnace pressure switch and understanding how it functions enables faster troubleshooting and safer repairs. Proper diagnosis avoids unnecessary part replacement and helps restore reliable heating performance.