Compartment Temperature Does Not Change, Or A/C System Does Not Respond Promptly: Wiring Diagram

WARNING: This page is about a different car, the 2013 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.

Air Conditioning System < Refer to appropriate SYSTEM WIRING DIAGRAM. >

Fig 1: Air Conditioning System - Wiring Diagram (Compartment Temperature Does Not Change)

Courtesy of SUBARU OF AMERICA, INC.

Step	Check	Yes	No
1 CHECK FUSE. Turn the ignition switch to OFF. Remove the fuse No. 22 from fuse & relay box. Check the condition of fuse.	Is the fuse blown out?	Replace the fuse.	Go to step 2 .
2 CHECK SIGNAL TO A/C RELAY AND AUTO A/C CONTROL MODULE. Disconnect the A/C relay and auto A/C control module harness connector. Turn the ignition switch to ON. Measure the voltage between A/C relay connector terminal and chassis ground. Measure the voltage between auto A/C control module harness connector terminal and chassis ground. Connector & terminal (F27) No. 17 (+) - Chassis ground (-): (i88) No. 11 (+) - Chassis ground (-):	Is the voltage 10 V or more?	Go to step 5 .	Go to step 3 .
3 CHECK POWER SUPPLY FOR PRESSURE SWITCH. Turn the ignition switch to OFF. Disconnect the pressure switch harness connector. Turn the ignition switch to ON. Measure the voltage between pressure switch harness connector terminal and chassis ground. Connector & terminal (B10) No. 2 (+) - Chassis ground (-):	Is the voltage 10 V or more?	Go to step 4 .	Check for open or short circuit in the harness between fuse and pressure switch.
4 CHECK HARNESS BETWEEN PRESSURE SWITCH AND A/C RELAY, AUTO A/C CONTROL MODULE. Turn the ignition switch to OFF. Measure the resistance of harness between pressure switch connector and A/C relay connector. Measure the resistance of harness between pressure switch connector and auto A/C control module connector. Connector & terminal (B10) No. 2 - (F27) No. 17: (B10) No. 2 - (i88) No. 11:	Is the resistance less than 1 Ω?	Check the pressure switch. < Refer to INSPECTION , Pressure Switch (Triple Pressure Switch). >	Repair the harness.
5 CHECK POWER SUPPLY FOR A/C RELAY. Measure the voltage between A/C relay connector terminal and chassis ground. Connector & terminal (F27) No. 14 (+) - Chassis ground (-):	Is the voltage 10 V or more?	Go to step 6 .	Check open or short circuit of harness between fuse and A/C relay.
6 CHECK A/C RELAY. Check the A/C relay. < Refer to INSPECTION , Relay and Fuse. >	Is the A/C relay normal?	Go to step 7 .	Replace the A/C relay.
7 CHECK A/C ON SIGNAL. Turn the ignition switch to OFF. Connect the A/C relay and all disconnected connectors. Start the engine and turn the A/C switch to ON. Turn the temperature control dial at maximum cool position. Measure the voltage between auto A/C control module harness connector terminal and chassis ground. Connector & terminal (i88) No. 36 (+) - Chassis ground (-):	Is the voltage 5.5 V or more?	Go to step 8 .	Replace the auto A/C control module. < Refer to REMOVAL , Control Unit (Auto A/C Model). >
8 CHECK HARNESS BETWEEN AUTO A/C CONTROL MODULE AND ECM. Turn the ignition switch to OFF. Disconnect the harness connector of auto A/C control module and ECM. Measure the resistance of harness between auto A/C control module connector and ECM connector. Connector & terminal (i88) No. 36 - (B136) No. 29:	Is the resistance less than 1 Ω?	Go to step 9 .	Repair the harness.
9 CHECK MAGNET CLUTCH ON SIGNAL. Stop the engine and turn the A/C switch to OFF. Turn the ignition switch to ON. Measure the voltage between ECM connector terminal and chassis ground. Connector & terminal (B136) No. 35 (+) - Chassis ground (-):	Is the voltage 10 V or more?	Go to step 10 .	Check for open or short circuit in the harness between A/C relay and ECM.
10 CHECK MAGNET CLUTCH ON SIGNAL. Start the engine and turn the A/C switch to ON. Turn the temperature control dial at maximum cool position. Measure the voltage between ECM connector terminal and chassis ground. Connector & terminal (B136) No. 35 (+) - Chassis ground (-):	Is the voltage 0 V?	Go to step 11 .	Replace the ECM. < Refer to REMOVAL , Engine Control Module (ECM). > < Refer to REMOVAL , Engine Control Module (ECM). >
11 CHECK POWER SUPPLY FOR MAGNET CLUTCH. Stop the engine and turn the A/C switch to OFF. Disconnect the harness connector of magnet clutch. Start the engine and turn the A/C switch to ON. Turn the temperature control dial at maximum cool position. Measure the voltage between magnet clutch harness connector terminal and chassis ground. Connector & terminal (F24) No. 1 (+) - Chassis ground (-):	Is the voltage 10 V or more?	Inspect the compressor. < Refer to INSPECTION , Compressor. >	Check for open or short circuit in the harness between A/C relay and magnet clutch.