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Circuit/System Verification

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Measure actual outside air temperature using a thermometer. Compare this value to the scan tool Outside Air Temp. Raw parameter. The measured temperature should be within 5 degrees of parameter.
    • If not within the specified range, refer to Ambient / Inside Air Temperature Sensor Circuit Malfunction.
  2. Measure actual inside air temperature using a thermometer. Compare this value to the scan tool Inside Air Temp. parameter. The measured temperature should be within 5 degrees of parameter.
    • If not within the specified range, refer to Ambient Temperature Sensor Circuit Malfunction.
  3. Measure actual temperature using a thermometer at the A/C evap. temperature sensor. Compare this value to the scan tool A/C Evap. Temperature Sensor parameter. The measured temperature should be within 5 degrees of the parameter.
    • If not within the specified range, refer to Evaporator Temperature Sensor Circuit Malfunction.

Ambient Temperature Sensor Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate temperature sensor.
  2. Test for less than 1 ohm between the low reference circuit terminal B and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.
  3. Ignition ON, verify the appropriate scan tool Temp Sensor Voltage parameter is greater than 4.9 volts or 250 counts.
    • If less than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the HVAC control module.
  4. Install a 3-amp fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Temp Sensor Voltage parameter is less than 0.1 volt or 5 counts.
    • If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
  5. If all circuits test normal, test or replace the appropriate temperature sensor.

Evaporator Temperature Sensor Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate temperature sensor.
  2. Test for less than 1.0 ohm between the low reference circuit terminal 2 and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.
  3. Ignition ON, verify the appropriate Temperature Sensor parameter is greater than 4.9 volts or 250 counts.
    • If less than the specified range, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the HVAC control module.
  4. Install a 3-amp fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the Scan Tool Temperature Sensor parameter is less than 0.1 volt or 5 counts.
    • If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
  5. If all circuits test normal, test or replace the appropriate temperature sensor.
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