HVAC System (Auto AC) (Diagnostics) (Except Sti): Other Subaru Impreza GH

PROCEDURE

DIAGNOSIS PROCEDURE

CAUTION

1. Never connect the battery in reverse polarity. Doing so may immediately damage the auto A/C control module.
2. Do not disconnect the battery terminals while the engine is running. A large counter electromotive force will be generated in the generator, and this voltage may damage electronic parts such as auto A/C control module etc.
3. Before disconnecting the connectors of sensors and the auto A/C control module, be sure to turn off the ignition switch. Auto A/C control module may be damaged.
4. Every A/C-related part is a precision part. Do not drop them.
5. Airbag system wiring harness is routed near the A/C control panel and junction box.

BATTERY

1. Measure the battery voltage and specific gravity of the electrolyte. Standard voltage: 12 V Specific gravity: 1.260 or more
2. Check the condition of the fuses for A/C system power supply and other fuses.
3. Check the condition of harness and harness connector connections.

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1. Turn the ignition switch to ON, and press the A/C switch.
2. Turn the temperature control dial to maximum hot position.
3. Set the blow vents to the DEF position.
4. Turn the fan switch to "MAX" position.
5. Put a strip of paper close to the front side of in-vehicle sensor suction port (A) located in the instrument panel lower cover, and check that air is being sucked into the port by seeing the paper moving towards the port. NOTE: Be careful not to let the paper get sucked into the port.
6. If the paper does not move at all, remove the instrument panel lower cover Refer to «REMOVAL»(ref-357250-S24911419492010031100000) , Instrument Panel Lower Cover. and check for poor connection of the aspirator hose (A), in-vehicle sensor and heater unit, and repair them if necessary.

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A/C LINE

Check the connection for A/C line (A) and lower side high-pressure pipe.

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CONTROL LINKAGE

1. Check the state of mode door linkage.
2. Check the state of air mix door linkage.
3. Check the state of FRESH/RECIRC door linkage.

CONTROL SWITCHES

Start the engine and warm up completely.

1. Inspection using switches SWITCHES INSPECTION CHART No. Point to check Switch operation Judgement standard 1 Air flow control dial Turn the dial to the right. Outlet opening (mode) switches AUTO --> VENT --> BI-LEVEL --> HEAT --> DEF/HEAT --> DEF each time turning the dial. 2 Fan speed control dial Turn the dial to the right. Each time the dial is turned, the fan speed switches OFF --> AUTO --> 1st --> 2nd --> 3rd --> 4th --> 5th --> 6th --> 7th. 3 FRESH/RECIRC switch Press the FRESH/RECIRC switch. Inlet opening switches RECIRC --> FRESH --> RECIRC each time pressing the switch. (LED illuminates at RECIRC) Set the air flow control dial and fan speed control dial to the AUTO position. The system switches to AUTO. 4 A/C switch Turn the A/C switch to ON with the fan speed control dial set to other than OFF position. The LED lights and the compressor operates. Set the air flow control dial and fan speed control dial to the AUTO position. The system switches to AUTO. 5 Auto function Operate in order from Set the following dial and switch to AUTO. Air flow control dial Fan speed control dial FRESH/RECIRC switch A/C switch Turn the temperature control dial completely to the left, and set to the maximum cool position. Outlet air temperature: COOL Fan speed: Max. Outlet opening: VENT Inlet opening: RECIRC Compressor: AUTO 3) Turn the temperature control dial to the right slowly up to the maximum hot position. Outlet air temperature: COOL --> HOT Fan speed: AUTO Outlet opening: AUTO Inlet opening: AUTO Compressor: AUTO 4) Turn the temperature control dial fully to the right, to the maximum hot position. Outlet air temperature: HOT Fan speed: Max. Outlet opening: HEAT Inlet opening: FRESH Compressor: AUTO 6 Defroster Interlock Function Set the air flow control dial to the DEF or the DEF/HEAT position. Outlet air temperature: AUTO Fan speed: AUTO Outlet opening: DEF or DEF/HEAT Inlet opening: FRESH Compressor: ON 7 Rear defogger switch Press the rear defogger switch. LED illuminates.
2. Inspection of compressor operation COMPRESSOR OPERATION INSPECTION CHART No. Point to check Switch operation Judgement standard 1 Compressor Turn the A/C switch to ON. Set the FAN switch between LO and HI. Compressor: ON
3. Inspection of illumination control ILLUMINATION CONTROL INSPECTION CHART No. Point to check Switch operation Judgement standard 1 Illumination Turn the lighting switch to ON. Illumination comes on. If the LED lights, the LED will dim.

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TERMINAL REFERENCE CHART

AIR CONDITIONER AUTO A/C MODEL

Refer to appropriate Air Conditioning System Wiring Diagrams in graphics in this article or in SYSTEM WIRING DIAGRAMS article.

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SENSOR CHECK TABLE

Note. When the sunload sensor check is performed indoors or in the shade, it could be diagnosed as having an open circuit. Always check the sunload sensor at a location exposed to direct sunlight.

SENSOR CHECK REFERENCE CHART

OPERATING MODE TABLE

OPERATING MODE REFERENCE CHART

DRIVE SIGNAL CHECK TABLE

DRIVE SIGNAL CHECK REFERENCE CHART