CARRIER DIAGNOSTIC REFERENCE STATUS LED — SHORT + LONG FLASH CODES DOC CARRIER-31

Carrier furnace: Code 31 — Pressure Switch Did Not Close or Reopened

Q: What does 3 short 1 long flashes mean on a Carrier furnace?

Code 31 — Pressure Switch Did Not Close or Reopened. If the switch stays open over 5 minutes, the inducer rests 15 minutes and retries. Official checklist: excessive wind, low inlet gas pressure (if LGPS used), disconnected or obstructed pressure tubing, defective switch.

YOUR LIGHT: 3 SHORT + 1 LONG FLASHES — MATCH IT ABOVE

Try DIY first, then call a pro

What does 3 short 1 long flashes mean on a Carrier furnace? If the switch stays open over 5 minutes, the inducer rests 15 minutes and retries. Official checklist: excessive wind, low inlet gas pressure (if LGPS used), disconnected or obstructed pressure tubing, defective switch.

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

Try these first — in this order

Vent terminations (snow, nests) and tubing — 15 minutes.

1Check: Blocked/disconnected tubing, wind-affected venting

Still showing the code? See every cause ↓ Get repair quotes near you

Switch and inducer testing. DIY part cost: $30–60 — a pro visit for this class of fault typically runs $150–350.

What causes it (in order of likelihood)

Blocked/disconnected tubing, wind-affected venting DIY-CHECKABLE
Defective pressure switch TECH

Parts referenced by this code

Pressure Switch

$30–60 · Model-specific

Amazon HVACDirect

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

Applies to

58STA · 58STX · Bryant 310/311/312 series · Payne PG8M series

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

Verified against Carrier 58STA/58STX Installation & Service Instructions (1106202L), p.37/48

Last verified 2026-07-06 · how we verify