AC Blower Only Works on High - Blower Motor Resistor Replacement

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Problem

AC blower fan only works on the high speed setting. Low and medium settings produce no air flow at all. Auto climate control only blows on high at extreme temperature settings (65-68 or 76-80), with clicking sounds behind the dash when adjusting temperature.

No air flow on low or medium blower settingsHigh speed blower works normally for both hot and cold airAuto climate mode only blows at extreme temperature settingsClicking sound behind dash when adjusting temperature up or down

Root Cause

Failed blower motor resistor. The resistor pack controls lower fan speeds by adding resistance to the blower motor circuit. When it fails (typically the thinnest wire coil breaks), only the high speed setting works because it bypasses the resistor entirely.

Confidence

Moderate confidence — Multiple community members agreed on this solution

View Original Thread →Posted August 2020 on SupraForums.com