Blower fan runs slower than expected in cold weather (when in AUTO mode) NOTE: It is normal for the blower fan to run slowly until the coolant temperature rises when in AUTO mode (2020 2021)

Diagnostic Procedure 

Probable cause: Engine coolant temperature (ECT) circuit malfunction

Troubleshoot the ECT sensor circuit:

• ECT Sensor 2 Out of Range
• ECT Sensor 2 Circuit Range/Performance Problem
• ECT sensor 2 circuit low voltage
• ECT sensor 2 circuit high voltage

Also Check for 

• Climate control DTCs 
• PGM-FI DTCs
• Blower motor operation