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Home >> Chrysler >> 2009 >> 300 Signature Series >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> (HVAC Systems (ATC) - Electrical Diagnostics) >> DTC Troubleshooting >> B1031-Evaporator Fin Temperature Sensor Circuit Low >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR DTC B1031-EVAPORATOR FIN TEMPERATURE SENSOR CIRCUIT LOW WITH EVAPORATOR TEMPERATURE SENSOR HARNESS CONNECTOR DISCONNECTED 
    Fig 1: Checking Evaporator Fin Temperature Sensor Circuit Low With Evaporator Temperature Sensor Harness Connector Disconnected
    GC0096315Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Disconnect the Evaporator Temperature Sensor harness connector.
    3. Turn the ignition on.
    4. With the scan tool, erase HVAC DTCs.
    5. Turn the ignition off, wait 10 seconds, and turn the ignition on.
    6. With the scan tool, read HVAC DTCs.

      Does the scan tool display: B1031-EVAPORATOR FIN TEMPERATURE SENSOR CIRCUIT LOW?

      Yes 

      • Go To  2

      No 

  2. CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND 
    Fig 2: Checking Evaporator Temperature Sensor Signal Circuit For A Short To Ground
    GC0096316Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Disconnect the A/C Heater Control C2 harness connector.
    3. Measure the resistance of the (C21) Evaporator Temperature Sensor Signal circuit between ground and the A/C Heater Control C2 harness connector.

      Is the resistance below 10k ohms?

      Yes 

      No 

      • Go to step  3
  3. CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO (C121) SENSOR GROUND CIRCUIT 
    Fig 3: Checking Evaporator Temperature Sensor Signal Circuit For A Short To Sensor Ground Circuit
    GC0096317Courtesy of CHRYSLER LLC
    1. Measure the resistance between the (C21) Evaporator Temperature Sensor Signal circuit and the (C121) Sensor Ground circuit in the A/C Heater Control C2 harness connector.

      Is the resistance below 10k ohms?

      Yes 

      No