HVAC●FAULTS
GOODMAN DIAGNOSTIC REFERENCE SINGLE RED LED — FLASH CODES DOC GOODMAN-3-FLASHES

Goodman furnace: Pressure Switch Stuck Open

YOUR LIGHT: 3 FLASHES — MATCH IT ABOVE

Try DIY first, then call a pro

What does 3 flashes mean on a Goodman furnace? After the induced-draft blower starts, the pressure switch never closes. The control locks out, then auto-resets and retries. Code: three short flashes and a pause.

GOOD NEWS: THE FIRST CHECKS ARE FREE AND TAKE MINUTES.

Try these first — in this order

Check the hose, outdoor vent terminations (snow/leaves), and the condensate trap — 15 minutes. The most common winter fix.

1Check: Disconnected or cracked pressure-switch hose (official)
2Check: Blocked flue / intake pipe, blocked drain, or weak inducer
Still showing the code? See every cause ↓ Get repair quotes near you

If venting and hoses are clear and it still trips, the switch or inducer is failing. DIY part cost: $25–60 — a pro visit for this class of fault typically runs $150–350.

What causes it (in order of likelihood)

  1. Disconnected or cracked pressure-switch hose (official) DIY-CHECKABLE
  2. Blocked flue / intake pipe, blocked drain, or weak inducer DIY-CHECKABLE
  3. Failed pressure switch or wiring TECH

Parts referenced by this code

Pressure Switch
$25–60 · Model-specific — match to your unit’s parts list
Amazon HVACDirect

Always match parts against your model's parts list — part numbers vary within a series.

Applies to

GMS8 · GDS8 · GHS8 · GMSS96 · GMH8 · GDH8

Different Goodman generations use different code maps. If your series isn't listed, don't assume this meaning — check your blower-door label.

Verified against Goodman GMS8/GDS8/GHS8 Service Manual (RS6612006), p.42 — “three short flashes followed by a pause”

Verified against Goodman GMSS96 Service Manual, p.32

Last verified 2026-07-06 · how we verify