ELECTRICAL FAN CONTROL [SKYACTIV-G 2.5]

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2014 - Mazda6 - Engine

ELECTRICAL FAN CONTROL [SKYACTIV-G 2.5]

Outline

Through cooling of the radiator and condenser by operation of the cooling fan according to vehicle conditions, engine reliability and cooling performance have been improved.

Block Diagram

Operation

The PCM determines the demand airflow volume by the following conditions.

Operation Pattern


Demand airflow volume	Cooling fan relay		Cooling fan motor
Demand airflow volume	No.1	No.2/No.3	No.1	No.2
No airflow	OFF	OFF	Stop	Stop
Small	ON	OFF	Low-speed	Low-speed
Large	ON	ON	High-speed	High-speed

Engine coolant temperature condition

Controls the PCM output duty ratio according to the engine coolant temperature.

The control temperature while the engine coolant temperature is decreasing is controlled differently than when it is increasing.

If high-load driving continues with low wind blowing against the vehicle, air bubbles in the fuel line could occur by the rise in the fuel temperature from the heat of the engine.

To prevent poor engine starting performance by air trapped in the fuel line from the occurrence of air bubbles, if the following conditions are met, the PCM operates the cooling fan (Demand airflow volume: Low).

Accumulated heat in engine compartment is extremely high

During travel (vehicle speed 10 km/h {6.2 mph} or more)

Engine coolant temperature: 90 °C {194 °F} or more

A/C operation condition

Controls the demand airflow volume depending on the refrigerant pressure and vehicle speed when the A/C switch is on.


Operation condition	Demand airflow volume
When all of the following conditions are met. Refrigerant pressure: 1.3 MPa {13 kgf/cm², 189 psi} or less, vehicle speed: 45 km/h {28 mph} or more Refrigerant pressure: 2.2 MPa {22 kgf/cm², 319 psi} or less, vehicle speed: 85 km/h {53 mph} or more	No airflow
When all of the following conditions are met. Refrigerant pressure: 1.3 MPa {13 kgf/cm², 189 psi} or less, vehicle speed: 45 km/h {28 mph} or less Refrigerant pressure: 1.3—1.5 MPa {14—15 kgf/cm², 189—217 psi}, vehicle speed: 85 km/h {53 mph} or less Refrigerant pressure: 1.5—2.2 MPa {16—22 kgf/cm², 218—319 psi}, vehicle speed: 65—85 km/h {41—52 mph}	Small
When all of the following conditions are met. Refrigerant pressure: 1.5—2.2 MPa {16—22 kgf/cm², 218—319 psi}, vehicle speed: 65 km/h {40 mph} or less Refrigerant pressure: 2.2 MPa {22 kgf/cm², 319 psi} or more	Large

After Cooling Control

If the engine is stopped directly after driving continuously at high load, air bubbles could occur in the fuel line due to the increase in the fuel temperature by the engine heat.

To prevent poor engine starting performance by air trapped in the fuel line from the occurrence of air bubbles, if the following conditions are met, the PCM operates the cooling fan for a maximum period of 9 min (demand airflow volume: Low).

Engine coolant temperature: 90°C {194 °F} or more

Accumulated heat in engine compartment is extremely high

Conditions during collision

If a collision signal from the SAS control module is received, the PCM stops the engine cooling fan to avoid use of battery voltage.

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