Goodman Furnace 3 Flashes — Pressure Switch / Ignition Fault
Three flashes on a Goodman furnace usually point to a pressure-switch circuit that will not close, or a related inducer/vent problem. On some boards the same flash pattern ties to ignition/flame sense — always read the sticker inside your door.
Updated July 2026 · 7 min read · United States
Symptoms
- Inducer starts, then furnace locks out
- LED shows 3 flashes (confirm against door chart)
- No heat; may hear clicking without ignition
Likely causes
- Blocked intake/exhaust PVC or bird nest in termination
- Cracked pressure-switch hose
- Failed pressure switch
- Dirty flame sensor (on boards that share this flash for flame faults)
What to do
1. Confirm the code on your door chart
Goodman flash meanings vary by board revision. Match the flash count to the label glued inside the blower door before ordering parts.
2. Inspect vent terminations
Look at the outdoor PVC intake and exhaust for snow, leaves, or nests. Clear gently — do not enlarge or relocate terminations yourself.
3. Check the rubber pressure hose
With power off, pull the hose from the pressure switch and inducer tap. Blow through it; replace if cracked, soft, or clogged with condensate sludge.
4. Clean the flame sensor if ignition was attempted
If the inducer and ignition sequence ran, remove the flame sensor rod and polish lightly with fine emery cloth — do not use sandpaper that leaves grit.
Stop and call a pro when
- You smell gas or the gas valve chatters repeatedly
- PVC venting is damaged or disconnected
- Combustion analysis or manometer readings are required
- The unit is still under warranty (OEM parts + licensed install required)
Related guides
- Carrier Code 33 — What Carrier furnace error code 33 means, how to safely check airflow and the limit switch, and which parts or filters usually clear the fault.
- Filter Size Guide — How to read furnace filter dimensions, why nominal vs. actual sizes differ, and which MERV rating to buy without starving airflow.
- Goodman 4 Flashes — What Goodman/Amana 4-flash limit codes mean, how to clear airflow restrictions safely, and which filter sizes or blower parts usually stop the trips.
- Goodman 1 Flash — Diagnose Goodman 1-flash ignition failure: dirty flame sensor, weak ignitor, and gas-valve issues — plus the parts homeowners most often replace.
- Rheem 2 Flashes — Rheem and Ruud 2-flash pressure-switch faults: blocked vents, bad hoses, and inducer issues — with the parts that clear most homeowner-accessible failures.
- York 3 Flashes — York Affinity and related Luxaire/Coleman 3-flash pressure-switch diagnostics for homeowners — vents, hoses, and when to stop DIY.
- Goodman 2 Flashes — Diagnose Goodman furnace LED 2-flash codes related to the pressure switch circuit, venting, and inducer operation.
- Rheem 3 Flashes — What Rheem and Ruud furnace 3-flash codes usually mean, safe vent checks, and when to call a licensed technician.
FAQ
Can I jump the pressure switch to test?
No. Jumping a pressure switch is a carbon monoxide risk and can damage the heat exchanger. Diagnose hose, vent, and inducer instead.
Does a dirty filter cause 3 flashes?
Usually not directly — but extreme restriction can affect combustion air on some configurations. Always start with vent and hose checks.
Need a licensed tech instead?
If the guide says to stop — or the part swap did not clear the fault — get free quotes from licensed local HVAC contractors.
Get matched with a pro