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MEDIUM URGENCY

York 3 Red Flashes — Pressure Switch Stuck Open

3 red flashes

Pressure switch open during inducer operation.

Brand: York (Also covers Coleman, Luxaire)  |  Equipment: Gas Furnace

What This Code Means

3 red flashes means the pressure switch did not close when the inducer started. Usually insufficient draft.

Likely Causes (Ranked)

Most common

Blocked exhaust vent

What: Snow, debris, or disconnected vent.

How to check: Inspect outdoor outlet.

Fix: Clear blockage.

Shop parts
Common

Failed inducer motor

What: Insufficient draft.

How to check: Listen at startup.

Fix: Replace inducer.

Shop parts
Common

Bad pressure switch

What: Switch won't close on proper pressure.

How to check: Tech test.

Fix: Replace switch.

Shop parts

Diagnostic Steps

  1. Check exhaust outlet
  2. Listen for inducer
  3. Inspect tubing
  4. Replace switch if needed

Frequently Asked Questions

Most common cause?
Blocked exhaust vent, especially in winter.
DIY?
Vent clearing yes.
Same on Coleman/Luxaire?
Yes.

Related York Codes

York Error Code 2 Red FlashesYork Error Code 6 Red Flashes

Related Symptoms

Furnace Not IgnitingFurnace Blowing Cold Air

Need More Help?

Try our interactive symptom diagnostic tool or browse York parts.

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