If your high-efficiency Goodman furnace starts up, runs for a moment, then shuts itself down — especially on cold or windy days — odds are you’re dealing with a pressure switch problem.
This isn’t a design flaw.
It’s a safety system doing its job.
But when homeowners don’t understand why it’s tripping, pressure switch issues turn into repeat lockouts, unnecessary service calls, and a lot of frustration.
100,000 BTU 96% AFUE Upflow/Horizontal Two Stage Goodman Gas Furnace - GR9T961004CN
Let’s break it down the way I’d explain it in your basement — clearly, safely, and without guessing.
🧠 What the Pressure Switch Actually Does (In Plain English)
The pressure switch answers one simple question:
👉 “Is it safe to light the burners?”
Before ignition, your furnace must prove:
-
The inducer motor is running
-
Exhaust gases can exit the home
-
Fresh air can enter the system
If airflow isn’t right, the furnace refuses to fire.
That’s the pressure switch saying “Nope — not safe yet.”
🧩 Why High-Efficiency Furnaces Trip Pressure Switches More Often
High-efficiency (90–96% AFUE) furnaces are more sensitive by design.
They use:
-
PVC intake and exhaust pipes
-
Condensate drains
-
Sealed combustion
More components = more places where airflow or drainage can be interrupted.
🔗 High-efficiency furnace basics (DOE):
https://www.energy.gov/products/furnaces
Jake’s perspective:
These furnaces aren’t fragile — they’re precise. Precision requires clear pathways.
🚨 Common Signs of a Pressure Switch Problem
You may notice:
-
Furnace starts, then shuts off
-
Repeated ignition attempts
-
Error code (often 2 or 3 flashes on Goodman units)
-
Works on mild days, fails in deep cold
-
Runs after a reset… then fails again
That pattern is classic pressure switch behavior.
🌬️ 🔁 The Most Common Cause: Blocked Intake or Exhaust Pipes
This is ground zero for pressure switch faults.
What blocks pipes?
-
Snow drifts
-
Ice buildup
-
Leaves or debris
-
Small animals
-
Improper vent termination
High-efficiency furnaces must breathe in and out freely.
🔗 Goodman venting requirements overview:
https://www.goodmanmfg.com/support/literature-library
Jake’s rule:
Always check outside first. It fixes more furnaces than tools ever will.
💧 Frozen or Clogged Condensate Drains (Huge Winter Issue)
Condensing furnaces produce water — and lots of it.
When drains fail:
-
Water backs up into pressure tubing
-
The switch can’t “prove” airflow
-
Furnace shuts down
Common culprits:
-
Frozen drain line
-
Dirty condensate trap
-
Poor drain slope
🔗 Condensate system explanation:
https://www.energy.gov/energysaver/furnaces-and-boilers
Jake’s cold-weather tip:
If the furnace fails overnight during a deep freeze, check the drain before resetting power.
🧪 Pressure Switch Tubing: Small Hose, Big Problem
That little rubber tube matters more than it looks.
Check for:
-
Water inside the tube
-
Cracks or brittleness
-
Loose connections
-
Kinks or sagging
Any of these can give the control board false information.
Jake’s warning:
Never blow into the tube to “test” it. That damages the switch.
⚙️ Inducer Motor Problems That Mimic Pressure Switch Failures
Sometimes the switch isn’t lying — it’s reporting a real problem.
If the inducer:
-
Doesn’t start
-
Sounds weak or noisy
-
Runs inconsistently
The furnace won’t get proper draft.
🔗 Inducer and airflow troubleshooting reference:
https://hvacoptimizer.net/goodman-furnaces-troubleshooting/
🔁 Pressure Switch Stuck Closed (Less Common, Still Important)
This usually shows as a 3-flash error code.
What it means:
The switch is showing “closed” before the furnace even starts.
Possible causes:
-
Water trapped in tubing
-
Failed pressure switch
-
Control board misreading input
Jake’s advice:
This is a diagnosis issue, not a reset issue. Repeated resets won’t solve it.
🚫 What You Should NEVER Do
Let me be very clear here.
❌ Do NOT jump or bypass the pressure switch
❌ Do NOT tape hoses together
❌ Do NOT force the furnace to run
The pressure switch protects against:
-
Exhaust gas buildup
-
Carbon monoxide risk
-
Heat exchanger damage
🔗 Furnace safety overview (CDC):
https://www.cdc.gov/carbon-monoxide/about/index.html
Jake’s bottom line:
If you bypass safety devices, you’re risking your home — not just your furnace.
🧰 Safe DIY Checks You Can Do
You can safely:
-
Clear snow/debris from vents
-
Inspect drain line for freezing
-
Replace dirty air filters
-
Ensure hoses are connected and dry
-
Confirm inducer motor runs
These steps solve a large percentage of pressure switch calls.
📞 When It’s Time to Call a Professional
Call a licensed tech if:
-
Pressure switch codes keep returning
-
Inducer motor is weak or loud
-
Switch trips immediately after replacement
-
You see water inside the furnace cabinet
-
Safety codes repeat
🔗 Find Goodman-authorized service:
https://www.goodmanmfg.com/support/find-a-dealer
🧠 Jake’s Quick Pressure Switch Checklist
✔ Check intake & exhaust outside
✔ Inspect condensate drain & trap
✔ Look for water in pressure tubing
✔ Confirm inducer motor operation
✔ Stop if safety codes repeat
Diagnosis beats replacement — every time.
🏁 Final Word from Jake
Pressure switch shutdowns feel random — but they’re not.
They’re the furnace saying:
“Something in my breathing system isn’t right.”
Fix the airflow. Fix the drainage. Fix the cause.
Do that, and your high-efficiency furnace will run quietly, safely, and reliably — exactly the way it was designed to.
