Compressor Control System

Compressor Control System

GENERAL

1. When the A/C switch and fan switch are turned ON, the A/C relay activates. The compressor is turned on, and then the main and sub fans also operate. Blower relay operates to direct the air flowrate determined by FAN switch position.
2. The thermo amplifier activates to stop the compressor clutch and main and sub fans.
3. When the "High-Low" pressure switch operates, the compressor clutch is stop and the main and sub fans are stop.

THERMO CONTROL AMPLIFIER




The thermo control amplifier disconnects the magnet clutch circuit to prevent the evaporator from becoming frosted when the temperature of the evaporator fin drops close to "3 °C (37 °F)". As the evaporator is cooled, the thermistor (located on the evaporator fin) interrupts the "base" current of the amplifier. This in turn deenergizes the A/C relay coil, which in turn disconnects the magnet clutch circuit.

ACCELERATION CUT SYSTEM




The A/C relay turns the A/C system on or off. The on-off operation of the switch is transmitted to the ECM.

The A/C relay breaks the current flow to the compressor, through the use of an output signal from the ECM, for a certain period of time when a "full-throttle" signal (emitted from the throttle sensor) enters the ECM while the compressor is operating. This prevents the degradation of acceleration performance and stabilizes the main fuse box located on the left side of the engine compartment.

I.S.C.




The I.S.C. increases engine idle speed when the compressor is turned ON.

The Engine Control module activates the idle speed control solenoid valve in advance to control the amount of by-pass air flowing through the throttle body in relation to the signal emitted from the A/C switch, so that the proper idle speed specified for each engine load is achieved.

FAN CONTROL




The main fan and sub fan are switch turn ON and OFF, according to the operating modes shown in the above table.