Error codes · York
York / Luxaire / Coleman 3 Flashes — Pressure Switch Fault
Three flashes on many York-family furnaces points to a pressure switch that will not close or stay closed. Start outdoors at the vent, then the rubber hose, then escalate.
Updated July 2026 · 5 min read · United States
Symptoms
- No heat after inducer start
- 3-flash LED pattern
- Intermittent operation on windy days
Likely causes
- Restricted venting
- Damaged pressure tubing
- Failed switch diaphragm
- Inducer not creating adequate draft
What to do
1. Inspect and clear vent terminations
Ensure both intake and exhaust are open. Ice storms commonly trigger this code on sidewall vents.
2. Reseat or replace the sensing hose
Hose must be airtight on both barbs. Replace if soft, split, or full of condensate sludge.
3. Listen to the inducer
Squealing or slow spin-up needs a technician. Do not oil sealed inducer motors.
Stop and call a pro when
- Code persists after clear vents and new hose
- You smell exhaust indoors
- Combustion analysis is required
Related guides
- 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.
- Goodman 3 Flashes — Diagnose Goodman (and Amana) furnace LED 3-flash codes: pressure switch, inducer, and flame-sensing failures — plus the parts that usually fix them.
FAQ
Can a dirty filter cause York 3 flashes?
Uncommon as the primary cause, but extreme restriction is still worth fixing while you troubleshoot.
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.
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