Carrier Furnace Error Code 12 Flash: How to Fix It

Q: What does Carrier furnace error code 12 flash mean?

Error code 12 flash means your blower motor is running even when the thermostat isn't calling for heat. This typically indicates problems with thermostat wiring, a stuck relay on the control board, or a malfunctioning thermostat sending incorrect signals to the furnace.

Q: Can I run my Carrier furnace with error code 12 flash?

While the furnace may still heat when called upon, running with error code 12 flash wastes energy and puts unnecessary wear on the blower motor. It's best to address the issue promptly to prevent higher utility bills and potential motor damage from continuous operation.

Q: How much does it cost to fix Carrier error code 12 flash?

Repair costs vary depending on the cause: thermostat replacement typically runs $100-250, low-voltage wiring repair costs $75-150, and control board replacement ranges from $200-400 including labor. Simple wiring reconnections may only cost a service call fee of $75-125.

Q: Why does my Carrier furnace blower keep running?

A continuously running blower with error code 12 flash usually results from stuck thermostat wiring, a faulty thermostat sending constant fan signals, or a stuck relay on the furnace control board. Check thermostat settings first, then inspect wiring connections for damage or corrosion.

Q: How do I reset my Carrier furnace after fixing error code 12?

After making repairs, turn off power to the furnace for 30 seconds, then restore power. The furnace will go through its startup sequence and the error code should clear if the problem is resolved. Set your thermostat to call for heat to test normal operation.

Abstract

Carrier furnace error code 12 flash indicates your blower motor is running even when there's no call for heat from the thermostat. This usually points to faulty thermostat wiring, a stuck relay on the control board, or issues with the thermostat itself.