Rheem / Ruud Furnace 2 Flashes — Pressure Switch Stuck Open
Two flashes on many Rheem/Ruud furnaces means the pressure switch did not close when the inducer started. Clear the vent terminations and sensing hose before replacing the switch itself.
Updated July 2026 · 6 min read · Canada
Symptoms
- Inducer runs; burners never stay lit
- Status light: 2 flashes
- Worse after storms, snow, or leaf season
Likely causes
- Blocked PVC intake/exhaust
- Soft or disconnected pressure hose
- Waterlogged condensate trap affecting draft
- Failed pressure switch or weak inducer
What to do
1. Clear outdoor terminations
Remove snow, nests, or debris from the two-pipe (or concentric) termination. Do not relocate vents yourself.
2. Replace brittle sensing hose
Power off. Swap cracked hose with HVAC-rated tubing cut to the same length and routing.
3. Check the condensate path
A clogged trap can upset pressure readings on high-efficiency units. Clear standing water if the trap is accessible and designed for homeowner service.
Stop and call a pro when
- Inducer sounds grinding or will not reach speed
- You need manometer readings on the switch
- Unit is under warranty
Related guides
- 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.
- York 3 Flashes — York Affinity and related Luxaire/Coleman 3-flash pressure-switch diagnostics for homeowners — vents, hoses, and when to stop DIY.
- 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 3 Flashes — What Rheem and Ruud furnace 3-flash codes usually mean, safe vent checks, and when to call a licensed technician.
FAQ
Is 2 flashes the same as Goodman 3 flashes?
Different makers use different flash maps. Always trust the chart inside your Rheem/Ruud door.
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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