Diagnostic Test

WARNING: This page is about a different car, the 2012 RAM Pickup. However, it is still accessible from the selected car via links, so may be relevant.

CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT VOLTAGE
1. Ignition on, engine not running.
2. With the scan tool, read HVAC DTC's.
  NOTE:
  It can take up to 30 seconds or more for this DTC to mature.
  
  Is this DTC active?
  
  Yes
  - Go To 2.
  No
  - Go To 5.
CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND

Fig 1: Checking Evaporator Temperature Sensor Signal Circuit For A Short To Ground
Courtesy of CHRYSLER GROUP, LLC
1. Turn the ignition off.
2. Disconnect the A/C Heater Control C1 harness connector.
3. Disconnect the Evaporator Temperature Sensor harness connector.
4. Measure the resistance between ground and the (C21) Evaporator Temperature Sensor Signal circuit.
  Is the resistance below 100k Ohms?
  
  Yes
  - Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to ground.
  - Perform HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Go To 3.
CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO (C121) SENSOR GROUND CIRCUIT

Fig 2: Checking Evaporator Temperature Sensor Signal Circuit For A Short To The Sensor Ground Circuit
Courtesy of CHRYSLER GROUP, LLC
1. Measure the resistance between the (C21) Evaporator Temperature Sensor Signal circuit and the (C121) Sensor Ground circuit.
  Is the resistance below 100k Ohms?
  
  Yes
  - Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to (C121) Sensor Ground circuit.
  - Perform HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Go To 4.
CHECK THE EVAPORATOR TEMPERATURE SENSOR
1. Replace the Evaporator Temperature Sensor in accordance with the Service Information.
2. Perform HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  Does the DTC reset?
  
  Yes
  - Replace the A/C Heater Control in accordance with the Service Information.
  - Perform HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Test complete.
CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set the DTC are not present at this time.
2. With the scan tool, check the Environmental Data to help identify the conditions in which the DTC was set.
3. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
4. Check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, or partially broken wires.
5. Check the connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals.
6. Wiggle the wiring and connectors while checking for shorted and open circuits.
  Were there any problems found?
  
  Yes
  - Repair as necessary.
  - Perform HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Test complete.