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Home >> Chrysler >> 2009 >> 300 Signature Series >> Repair and Diagnosis >> External Pages >> Different car >> Section 248 ((HVAC Systems - Electrical Diagnostics)) >> HVAC - Electrical Diagnostics >> DTC Troubleshooting >> DTC 31: Evaporator Sensor Open (MTC) >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2008 Dodge Magnum, 2008 Dodge Charger, and 2008 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE 
    Fig 1: Checking Evaporator Temperature Sensor Signal Circuit
    GC0013830Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Disconnect the A/C Heater Control C2 harness connector.

    Turn the ignition on.

    Measure the voltage of the (C21) Evaporator Temperature Sensor Signal circuit.

    Is the voltage above 0.2 volts? 

    Yes 

    1. Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to voltage.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  2.
  2. CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT, (C121) SENSOR GROUND CIRCUIT, & EVAPORATOR TEMPERATURE SENSOR 
    Fig 2: Checking Evaporator Temperature Sensor Signal Circuit
    GC0013831Courtesy of CHRYSLER LLC

    Turn the ignition off.

    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. The approximate circuit resistance should be as follows:

    • 1468 ohms @ 40°C (104°F)
    • 1800 ohms @ 35°C (95°F)
    • 2221 ohms @ 30°C (86°F)
    • 2757 ohms @ 25°C (77°F)
    • 3443 ohms @ 20°C (68°F)
    • 4330 ohms @ 15°C (59°F)
    • 5485 ohms @ 10°C (50°F)
    • 6998 ohms @ 5°C (41°F)
    • 7354 ohms @ 4°C (39°F)
    • 7731 ohms @ 3°C (37°F)
    • 8130 ohms @ 2°C (36°F)
    • 8553 ohms @ 1°C (34°F)
    • 9000 ohms @ 0°C (32°F)

    Is the resistance within the specifications? 

    Yes 

    1. Replace the A/C Heater Control in accordance with the Service Information.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  3.
  3. CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR AN OPEN 
    Fig 3: Checking Evaporator Temperature Sensor Signal Circuit
    GC0013832Courtesy of CHRYSLER LLC

    Disconnect the Evaporator Temperature Sensor harness connector.

    Measure the resistance of the (C21) Evaporator Temperature Sensor Signal circuit between the Evaporator Temperature Sensor harness connector and the A/C Heater Control C2 harness connector.

    Is the resistance below 5.0 ohms? 

    Yes 

    1. Go To step  4.

    No 

    1. Repair the (C21) Evaporator Temperature Sensor Signal circuit for an open.
    2. Perform BODY VERIFICATION TEST - VER 1 .
  4. CHECK (C121) SENSOR GROUND CIRCUIT FOR AN OPEN 
    Fig 4: Checking Sensor Ground Circuit
    GC0013833Courtesy of CHRYSLER LLC

    Measure the resistance of the (C121) Sensor Ground circuit between the Evaporator Temperature Sensor harness connector and the A/C Heater Control C2 harness connector.

    Is the resistance below 5.0 ohms? 

    Yes 

    1. Replace the Evaporator Temperature Sensor in accordance with the Service Information.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Repair the (C121) Sensor Ground circuit for an open.
    2. Perform BODY VERIFICATION TEST - VER 1 .
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