Mazda RX-8 2004 - A;C Cut-Off at High ECT; Electrical Fan Control Block Diagram; Electrical Fan Control Operation; Electrical Fan Control Outline

CONTROL SYSTEM
01–40–37
01–40
A/C Cut-off at High ECT
• When the ECT exceeds 110 °C {230°F} during
the A/C operation, the A/C relay alternately turns
on and off approx. every 10 s to protect the
engine and to prevent deterioration of the A/C
function.
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ELECTRICAL FAN CONTROL OUTLINE
CHU014000140S45
• Cooling fan relays No.1, No.2, and No.3 turn on and off to control operation timing and rotation speed of the
cooling fan motor according to the engine conditions. Due to this, the radiator and condenser are cooled
efficiently, preventing overheating and overcooling.
• The electrical fan control includes the regular-driving cooling function and the after-cooling function.
• The regular-driving cooling function operates according to the engine conditions during the engine operation.
• The after-cooling function operates when the vehicle has stopped at high engine temperature (ignition switch
off).
• After the ignition switch is turned off, a main relay on request is sent to operate the after-cooling function. (See
01–40–10 MAIN RELAY CONTROL OPERATION.)
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ELECTRICAL FAN CONTROL BLOCK DIAGRAM
CHU014000140S46
• The PCM determines the engine conditions based on input signals and sends an on/off signal to cooling fan
relay No.1 or No.2/No.3.
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ELECTRICAL FAN CONTROL OPERATION
CHU014000140S47
• When the operation conditions are met for each function, the PCM sends an operation signal to cooling fan
relay No.1 or No.2/No.3 to operate the cooling fan motors.
• The rotation speed of the cooling fan motor is switched between two levels according to a combination of the
cooling fan relays.
• When only cooling fan relay No.1 is on, the rotation speed is low and when in addition to No.1, No.2 and No.3
are on, rotation speed is high.
A/C
SWITCH
ECT
A/C
RELAY
ON
OFF
ON
OFF
110 °C
{230 °F}
10
10
(SEC.)
10
CHU0140S078
PCM
ECT SENSOR
IAT SENSOR
A/C AMPLIFIER (A/C SWITCH)
COOLING FAN RELAY NO.1
IGNITION SWITCH
COOLING FAN RELAY NO.2
COOLING FAN RELAY NO.3
REFRIGERANT PRESSURE SWITCH
(MEDIUM PRESSURE SWITCH)
CHU0140S035