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.
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HOMESERVICE MANUALSCHEVROLET1998METRO L4-079 1.3L VIN 2 MFIREPAIR AND DIAGNOSISHEATING AND AIR CONDITIONINGCONTROL MODULE HVACDESCRIPTION AND OPERATIONBLOWER CONTROLS
1998 Chevrolet Metro L4-079 1.3L VIN 2 MFI
Blower Controls
1998 Chevrolet Metro L4-079 1.3L VIN 2 MFISECTION Blower Controls
Battery voltage is applied through the HEATER fuse to the blower speed selector switch when the ignition switch is in the ON position. When the blower speed selector switch is moved to the LOW position system voltage is applied through the closed contacts of the blower speed selector switch. With the blower speed selector switch in the LOW position the current must travel all the way through the resistive element in the blower motor resistor before traveling to ground through the blower motor. The voltage reduction caused by the blower motor resistor maintains the blower motor at LOW speed.
When the blower speed selector switch is in the M1 position voltage passes partially through the blower motor resistor before reaching ground through the blower motor. The circuit resistance is lower because less of the blower motor resistor is part of the circuit. The voltage potential at the blower motor is therefore higher causing the blower motor to operate at a higher speed than in the LOW position.
The M2 operation is identical to the M1 operation with the exception that even less of the blower motor resistor is in the circuit. The blower motor operation in M2 is faster than the operation is in M1.
With the blower speed selector switch in the HIGH position the voltage bypasses the blower motor resistor entirely. The voltage passes directly through the blower motor to ground. Since the resistance in the ground path is nearly 0, the blower motor operates on full system voltage and at full speed.
When the blower speed selector switch is in the M1 position voltage passes partially through the blower motor resistor before reaching ground through the blower motor. The circuit resistance is lower because less of the blower motor resistor is part of the circuit. The voltage potential at the blower motor is therefore higher causing the blower motor to operate at a higher speed than in the LOW position.
The M2 operation is identical to the M1 operation with the exception that even less of the blower motor resistor is in the circuit. The blower motor operation in M2 is faster than the operation is in M1.
With the blower speed selector switch in the HIGH position the voltage bypasses the blower motor resistor entirely. The voltage passes directly through the blower motor to ground. Since the resistance in the ground path is nearly 0, the blower motor operates on full system voltage and at full speed.
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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.