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A/C Signals Circuit Check: Aerio

WARNING: This page is about a different car, the 2003 Suzuki XL-7, 2003 Suzuki Vitara, 2003 Suzuki Grand Vitara, and 2003 Suzuki Aerio. However, it is still accessible from the selected car via links, so may be relevant.
  1. With ignition switch OFF, disconnect ECM connectors and check resistance between ECM connector G04 terminal No. 20 and 18 & terminal No. 6 and 18. See Figure . Resistance should be 6.3-6.9 k/ohms at 32°F (0°C) and 1.8-2.2 k/ohms at 77°F (25°C). If resistance is within specification, go to next step. Is resistance is not as specified, A/C evaporator temperature sensor or its circuits are faulty.
  2. Measure voltage at ECM connector G04 terminal No. 28. Voltage should be 10-14 volts with ignition switch ON and A/C switch OFF. With ignition switch ON and A/C switch ON, voltage should be 0-1 volt. If voltage is as specified, go to next step. If voltage is not as specified, check Green/Black wire for open or short. Check ECM connector G04 terminal No. 28 for poor connection. If wire and connector are fine, substitute a known-good ECM and recheck.
  3. Turn blower switch ON. If A/C cooling fan starts, go to step  7 . If A/C cooling fan does not start, go to next step.
  4. Measure voltage at ECM connector G04 terminal No. 32. Voltage should be 10-14 volts with ignition switch ON and A/C switch OFF. With ignition switch ON and A/C switch ON, voltage should be 0-1 volt. If voltage is as specified, go to next step. If voltage is not as specified, check Blue/Yellow wire for open or short. Check ECM connector terminal No. 32 for poor connection. If wire and connector are fine, substitute a known-good ECM and recheck.
  5. With ignition switch OFF, remove A/C condenser fan control relay. Check for proper connection to relay at terminals 1 and 2. If Okay, check for continuity between 1 and 2 when battery is connected to terminals 3 and 4. See Figure If check result is satisfactory, go to next step. If result is not satisfactory, replace A/C condenser fan control relay.
  6. With ignition turned OFF, disconnect A/C condenser fan motor connector and Check for proper connection at Red/Blue and Black terminals. If OK, connect battery to motor and check for operation. If motor is in good condition, Red/Blue or Black circuit open. If motor is not in good condition, replace A/C condenser fan motor.
  7. Turn A/C switch and heater blower switch ON. IF A/C compressor starts, A/C control system is in good condition. If A/C compressor does not start, go to next step.
    8. NOTE: When A/C evaporator thermistor temp. is below 36.5°F (2.5°C), A/C remains OFF (C45-21 terminal voltage becomes 0-1 volt). This condition is not abnormal.
  8. Measure voltage at ECM connector C45 terminal No. 21. With engine running and A/C switch OFF, voltage should be 10-14 volts. With engine running and A/C switch ON, voltage should be 0-1 volt. If voltage is not as specified, check Brown/Yellow wire for open or short. Check ECM connector G04 terminal No. 28 for poor connection. If wire and connector are fine, substitute a known-good ECM and recheck.
  9. With ignition switch OFF, remove A/C compressor control relay. Check for proper connection to relay at terminals 1 and 2. If OK, check for continuity between 1 and 2 when battery is connected to terminals 3 and 4. See Figure . If check result is satisfactory, check A/C compressor. If result is not satisfactory, replace A/C compressor control relay.
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