Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Blower Speed Controller (BSC)
The BSC varies blower motor speed by varying resistance in blower motor ground circuit. The EATC module sends a varying voltage signal to a power transistor in BSC. See Fig 1. Current flows through the blower motor and power transistor to ground. BSC has delay function to gradually increase and decrease blower motor speed. A high-speed blower relay, integral with BSC, provides power for maximum blower speed.
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Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.