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MEDIUM URGENCY

Carrier Code 23 — Pressure Switch Didn't Open

Code 23 (2 short + 3 long flashes)

Pressure switch did not open — stuck switch or tubing obstruction.

Brand: Carrier (Also covers Bryant, Payne)  |  Equipment: Gas Furnace

What This Code Means

Code 23 means the pressure switch failed to open when the inducer motor was off. The switch should reset to its 'open' position between heating cycles. When it stays closed, the control sees code 23.

Likely Causes (Ranked)

Most common

Stuck-closed pressure switch

What: Switch contacts are stuck in the closed position.

How to check: Disconnect switch leads, test continuity with inducer off (should be open).

Fix: Replace pressure switch.

Shop parts
Common

Obstructed pressure tubing

What: Debris, water, or kink in the tubing affects pressure readings.

How to check: Inspect rubber/plastic tubing from inducer to switch for kinks or moisture.

Fix: Clear or replace tubing.

Shop parts
Less common

Bad control board

What: Board incorrectly reads the pressure switch state.

How to check: Test switch independently; if switch is good, board is suspect.

Fix: Replace control board.

Shop parts

Diagnostic Steps

  1. Cut power and inspect pressure switch tubing
  2. Disconnect tubing and check for debris/water
  3. Test switch continuity (cold, inducer off = open)
  4. Replace switch if stuck closed
  5. Call tech if tubing and switch both check out

Frequently Asked Questions

What does Carrier code 23 mean?
The pressure switch is stuck closed when it should be open. This usually means a failed switch or blocked tubing.
Can I replace a Carrier pressure switch myself?
Yes, if comfortable with basic HVAC work — switches are typically $25-60 and held in by 1-2 screws with two wire leads.
Same code on Bryant or Payne?
Yes, all three brands share the same control board and codes.

Related Carrier Codes

Carrier Error Code 31Carrier Error Code 33

Related Symptoms

Furnace Not IgnitingFurnace Blowing Cold Air

Need More Help?

Try our interactive symptom diagnostic tool or browse Carrier parts.

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