Carrier Error Code 12: Blower On After Power Up
LED Blink Pattern
1 short blink, 2 long blinks.
How to Fix Carrier Code 12
- Step 1: Turn off the HVAC system at the thermostat.
- Step 2: Wait a few minutes, then turn the system back on to see if the error clears. If it doesn't, proceed to the next step.
- Step 3: Contact a qualified HVAC technician to diagnose and repair the issue.
How to Reset Carrier Code 12
- 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 12 Mean?
The Carrier error code 12, signaled by a specific LED blink pattern on the control board, indicates that the blower motor is running when it shouldn't be immediately after the unit powers up. This typically points to a problem within the system's control logic, preventing the blower motor from cycling on and off as expected. It's not a gas leak or immediate safety hazard, but it will likely prevent your system from heating or cooling your home effectively. This issue often arises from a faulty relay on the control board that's stuck in the 'on' position, or a miscommunication between the thermostat and the unit's control board. In some cases, it could also be a sign of a failing blower motor that's not responding correctly to the control signals. Because it involves electrical components, troubleshooting should be left to a qualified HVAC technician.
Common Causes
- Stuck or faulty blower relay on the control board
- Short circuit in the blower motor wiring
- Defective blower motor
- Faulty control board
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Blower runs immediately after power up | Check voltage at the blower motor terminals | 0 VAC when the thermostat is not calling for heat or cool |
| Voltage present at blower motor terminals when it should be off | Inspect the blower relay on the control board for signs of damage or sticking | Relay contacts should be open when no call for blower |
| Relay appears normal | Check the wiring between the control board and blower motor for shorts | No continuity between the blower motor wires and ground |
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 |
|---|---|---|---|
| Blower Motor Relay | — | — | — |
| Control Board | — | — | — |
| Blower Motor | — | — | — |
Related Codes on Same Models
Other codes that affect the same Carrier model families as 12.
| Code | Description | Severity |
|---|---|---|
| 13 | Limit/Rollout Fault | Critical |
| 14 | Ignition Lockout | Critical |
| 21 | Gas Heating Lockout | Critical |
| 22 | Abnormal Flame | Critical |
| 23 | Pressure Switch Fault | Warning |
| 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 |