Code 45 — Control Fault

What does 45 mean?

This general fault code indicates an internal control board malfunction or error affecting various Carrier products like Furnace, Fan coil, GeoHP, Greenspeed/Extreme, and Infinity/Evolution ODU units. The system's main brain is experiencing an issue.

• Internal control board failure
• Power surge or brownout
• Software or firmware issue
• Sensor failure affecting control logic

Click steps to track your progress.

1. 1

   Turn off the power to the entire HVAC system at the circuit breaker for at least 30 seconds.

2. 2

   Restore power and observe if the system initializes correctly and the fault clears.

3. 3

   Check your thermostat for any additional error messages or unusual behavior.

4. 4

   If the control fault persists, contact a qualified HVAC technician for diagnosis and potential control board replacement.