System Diagnosis
Blower Motor Fault. Blower failed to reach 250 RPM or failed to communicate within the prescribed time limits.
Troubleshooting guide for the Carrier Furnaces system fault 41.
Loss of comm LEDs, incorrect polarity, or a fault that appears only when indoor and outdoor boards talk.
Board swaps without harness checks can hide the real fault if the wiring path is damaged.
ACLogics walks you through Carrier Furnaces diagnostics step-by-step — so you confirm the cause before swapping parts.