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.
2003 Ford Mustang Mach 1, AutomaticFACTORY OEM SERVICE PROCEDURE
Climate Control Assembly
The climate control assembly has three system controls:
- The blower motor switch controls blower motor speed by adding or bypassing resistors in the heater blower motor resistor.
- The temperature selection is accomplished with a manually-controlled blend door actuator that controls positioning of the temperature blend door. Movement of the control knob (18519) from COOL (blue) to WARM (red) causes a corresponding movement on the air temperature control door and determines the temperature that the system will maintain.
- The A/C heater function selector switch combines a vacuum selector valve for direct control of the vacuum control motors and electrical input to the instrument control module.
Factory Service Tools
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.