Blower Fan Runs Slower Than Expected In Cold Weather (When In Auto Mode)

Blower fan runs slower than expected in cold weather (when in AUTO mode)

Probable cause: Engine coolant temperature (ECT) circuit malfunction

Troubleshoot the ECT sensor circuit:

ECT sensor 2 circuit low voltage DTC Troubleshooting

ECT sensor 2 circuit high voltage DTC Troubleshooting

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Climate control DTCs Initial Inspection and Diagnostic Overview

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Powertrain DTCs

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Blower motor operation