Forester S F4-25L DOHC (1998) HVAC Control Assembly Diagrams Page
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
