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.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSSUBARU1996LEGACY WAGON 4WD F4-2.2L SOHCREPAIR AND DIAGNOSISHEATING AND AIR CONDITIONINGDESCRIPTION AND OPERATIONAIR CONDITIONING SYSTEMCOMPRESSOR CONTROL SYSTEM
1996 Subaru Legacy Wagon 4WD F4-2.2L SOHC
Compressor Control System
1996 Subaru Legacy Wagon 4WD F4-2.2L SOHCSECTION Compressor Control System
Compressor Control System
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 flow rate determined by FAN switch position.
2. The thermo amplifier activates to stop the main and sub fans, and disengage compressor clutch.
3. When the "High-Low" pressure switch operates, disengage the compressor clutch, and the main and sub fans are stop.
COMPRESSOR CLUTCH "ON" DELAY SYSTEM
- When air conditioning system relay operates, a signal is entered into engine control module. Engine control module then judges engine operation and activates A/C relay. Maximum clutch "ON" delay occurs 0.8 seconds after A/C relay activates.
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 discharge air 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 ECU.
- The A/C relay breaks the current flow to the compressor, through the use of an output signal from the ECU, for a certain period of time when a "full-throttle" signal (emitted from the throttle sensor) enters the ECU while the compressor is operating. This prevents the degradation of acceleration performance and stabilizes. A/C relay located in the main fuse box.
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.
Compressor Control System - Schematic:
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 flow rate determined by FAN switch position.
2. The thermo amplifier activates to stop the main and sub fans, and disengage compressor clutch.
3. When the "High-Low" pressure switch operates, disengage the compressor clutch, and the main and sub fans are stop.
COMPRESSOR CLUTCH "ON" DELAY SYSTEM
- When air conditioning system relay operates, a signal is entered into engine control module. Engine control module then judges engine operation and activates A/C relay. Maximum clutch "ON" delay occurs 0.8 seconds after A/C relay activates.
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 discharge air 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 ECU.
- The A/C relay breaks the current flow to the compressor, through the use of an output signal from the ECU, for a certain period of time when a "full-throttle" signal (emitted from the throttle sensor) enters the ECU while the compressor is operating. This prevents the degradation of acceleration performance and stabilizes. A/C relay located in the main fuse box.
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.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.