Blower Fan Runs Slower Than Expected In Cold Weather (When In AUTO Mode) (Without Climate Control)

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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Manual blower motor operation

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Engine thermostat