Code 12 — Furnace Blower on after Power-up

What does 12 mean?

This fault indicates that the furnace blower motor detected it was running immediately after the system powered up. This could point to an issue with the blower control or its sensor.

• Blower motor control issue
• Sensor malfunction
• Improper wiring or installation
• Power surge or transient event

Click steps to track your progress.

1. 1

   Turn off the power to the furnace at the circuit breaker for at least 30 seconds.

2. 2

   Restore power and observe if the blower operates normally.

3. 3

   Ensure the thermostat is set correctly and not calling for continuous fan operation.

4. 4

   If the issue persists, contact a qualified HVAC technician for inspection.