45
Moderate
Carrier · Central Air Conditioners & Furnaces
Control Circuitry Lockout
Quick Answer
Error code 45 on your Carrier Central Air Conditioners & Furnaces means: Control Circuitry Lockout. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
Likely Causes
How to Fix It
1
Power cycle the furnace by turning off the power for 60 seconds and restoring
2
Check all wire connections on the control board for tightness and corrosion
3
Review the LED fault history on the control board for previous codes
4
If the lockout recurs immediately, the control board likely needs replacement
5
A licensed HVAC technician should diagnose this to rule out safety-critical component failures
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Control board
Wire connectors
Board mounting hardware
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