Bryant 340MAV Error Code 23: Pressure Switch Did Not Open
What Does Code 23 Mean?
Status code 23 on the Bryant 340MAV indicates the pressure switch did not open as expected during the furnace operating sequence. The pressure switch monitors the negative pressure generated by the inducer motor and should open (break contact) at a specific point in the heating cycle to prove the draft condition changed correctly.
The service documentation for the 340MAV identifies four possible causes: obstructed pressure tubing, a pressure switch stuck closed, a defective inducer motor, and a defective pressure switch. Obstructed tubing is the most common cause — kinks, clogs, or disconnections in the hose prevent the switch from sensing the pressure change. A stuck-closed switch has a mechanical failure in its diaphragm or contacts. A defective inducer motor may not create the expected pressure change, and a defective switch may fail to open even when conditions are correct.
Code 23 is the mirror image of code 31 (pressure switch did not close or reopened): where code 31 is about the switch failing to make on adequate draft, code 23 is about it failing to break when the draft condition changes. Both are safety interlocks tied to the inducer and venting system.
What You'll Notice
- The furnace fails to complete its startup sequence and produces no heat
- The inducer may run, but the sequence stalls before or during ignition
- The fault appears at the point in the cycle where the switch is expected to change state
- Cycling the thermostat does not clear it because the switch is not behaving as the control expects
Common Causes
How This Is Diagnosed
A technician starts with the most accessible item — the pressure tubing — checking for kinks, condensate, clogs, or a disconnected hose. The pressure switch contacts are then tested with a multimeter to see whether they are stuck closed, and the inducer motor's current draw and draft are measured to confirm it is operating correctly. The switch is condemned only after the tubing and inducer have been ruled out.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- The furnace will not complete a heating cycle with code 23 active
- The inducer motor sounds abnormal or does not run smoothly
- The pressure tubing or switch needs testing or replacement
- Only OEM pressure switches matched to the 340MAV's inducer specifications should be used
Frequently Asked Questions
What does a pressure switch that 'did not open' mean?
The switch should change state at a certain point in the cycle. Code 23 means it stayed closed when the control expected it to open, usually from obstructed tubing or a stuck switch. A technician must diagnose it.
Can I fix code 23 myself?
No. All of its causes — pressure tubing, the switch, and the inducer motor — require testing and internal access that are not homeowner-safe on this furnace.
✓ Verified against manufacturer service manual — March 2026