Carrier Error Code 23: Pressure Switch Fault
Warning: Your Carrier furnace has detected a pressure switch fault, which prevents it from starting for safety reasons. A professional HVAC technician is needed to diagnose and repair the issue.
LED Blink Pattern
2 short blinks, 3 long blinks.
How to Fix Carrier Code 23
- Step 1: Check the air filter. A severely clogged filter can sometimes restrict airflow enough to trigger a pressure switch fault.
- Step 2: Visually inspect the vent pipes (both intake and exhaust) outside your home for any obvious obstructions like snow, ice, or debris. Safely clear any blockages you can reach.
- Step 3: If the problem persists after checking the filter and vents, contact a qualified HVAC technician to diagnose and repair the issue.
How to Reset Carrier Code 23
- Turn off the furnace power switch, usually located on or near the unit.
- Turn off the circuit breaker for the furnace. Wait 30 seconds.
- Restore power at the breaker and flip the furnace switch back on.
- Set the thermostat to call for heat. If the error code returns after 2-3 ignition attempts, the fault requires repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Carrier Error Code 23 Mean?
The Carrier 23 error code, indicated by a specific blinking pattern on the unit's LED, signifies a problem with the pressure switch circuit. This switch is a crucial safety component that verifies proper venting before allowing the furnace to ignite. When the furnace induces draft, the pressure switch should close, proving that exhaust gases will vent properly. If the control board does not see the switch close, it will display error code 23 and shut down the unit to prevent potential hazards.
Common Causes
- Blocked vent pipe (intake or exhaust)
- Failed pressure switch
- Loose or disconnected pressure switch tubing
- Faulty inducer motor
- Defective control board
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Furnace displays error code 23 | Visually inspect pressure switch tubing for kinks, cracks, or disconnections | Tubing is intact and properly connected to the pressure switch and inducer housing. |
| Tubing is OK | With the furnace OFF, use a multimeter to measure the resistance across the pressure switch terminals | Should read open circuit (infinite resistance). |
| Switch is open | Start a call for heat, then measure voltage to the inducer motor | 120VAC |
| Inducer voltage OK | With the inducer running, use a manometer to measure pressure at the pressure switch port on the inducer housing. | Should meet or exceed the pressure switch's rated actuation pressure (e.g., -0.5" WC) |
Applicable Carrier Models
- 24ABC6 Air Conditioner(electric)
- 25HBC5 Heat Pump(electric)
- Base Series(gas)
- Base Series Furnace(gas)
- Comfort 80 Gas Furnace(gas)
- Comfort Series(electric)
- Comfort Series Furnace(gas)
- Comfort Series Heat Pump(electric)
- Infinity 20 Heat Pump with Greenspeed Intelligence(electric)
- Infinity 80(gas)
- Infinity Series(electric)
- Infinity Series Furnace(gas)
- Infinity Series Heat Pump(electric)
- Performance Boost 95 Furnace(gas)
- Performance Boost Furnace(gas)
- Performance Series(gas)
- Performance Series Furnace(gas)
- Performance Series Heat Pump(electric)
- WeatherMaker 8000(gas)
- WeatherMaker 9300(gas)
- WeatherMaker Furnace(gas)
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Pressure Switch | — | — | — |
| Inducer Motor | 326461-756 | — | Find Part |
| Control Board | HK42FZ004 | — | Find Part |
Related Codes on Same Models
Other codes that affect the same Carrier model families as 23.
| Code | Description | Severity |
|---|---|---|
| 12 | Blower On After Power Up | Warning |
| 13 | Limit/Rollout Fault | Critical |
| 14 | Ignition Lockout | Critical |
| 21 | Gas Heating Lockout | Critical |
| 22 | Abnormal Flame | Critical |
| 24 | Secondary Voltage Fuse | Warning |
| 31 | High Stage Pressure Fault | Warning |
| 32 | Low Flame Sense | Warning |
| 33 | Limit/Rollout Switch Lockout | Critical |
| 34 | Ignition/Flame Sense Fault | Warning |