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 after 60 seconds.
  Is this DTC active?
  
  Yes
  - Go To 2.
  No
  - Go To 7.
CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT VOLTAGE

Fig 1: Measuring Evaporator Temperature Sensor Signal Circuit Voltage
Courtesy of CHRYSLER GROUP, LLC
1. Turn the ignition off to the lock position.
2. Disconnect the Evaporator Temperature Sensor harness connector.
  NOTE:
  Due to the small terminal and pin size of the Evaporator Temperature Sensor and harness connector, make sure to not damage the terminals in this process.
3. Connect a jumper wire between the (C21) Evaporator Temperature Sensor Signal circuit and the (C121) Sensor Ground circuit in the Evaporator Temperature Sensor harness connector.
4. Ignition on, engine not running.
5. With the scan tool, read the Evaporator Temperature Sensor voltage.
  Is the voltage below 0.2 of a volt?
  
  Yes
  - Replace the Evaporator Temperature Sensor in accordance with the Service Information.
  - Perform HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Go To 3.
CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE

Fig 2: Checking Evaporator Temperature Sensor Signal Circuit For A Short To Voltage
Courtesy of CHRYSLER GROUP, LLC
1. Turn the ignition off to the lock position.
2. Disconnect the jumper wire from the previous step.
3. Disconnect the A/C Heater Control C1 harness connector.
4. Ignition on, engine not running.
5. Measure the voltage of the (C21) Evaporator Temperature Sensor Signal circuit.
  Is voltage above 0.2 of a volt?
  
  Yes
  - Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to voltage.
  - Perform HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Go To 4.
CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR AN OPEN

Fig 3: Checking Evaporator Temperature Sensor Signal Circuit For An Open
Courtesy of CHRYSLER GROUP, LLC
1. Turn the ignition off to the lock position.
2. Measure the resistance of the (C21) Evaporator Temperature Sensor Signal circuit between the A/C Heater Control C1 harness connector and the Evaporator Temperature Sensor harness connector.
  Is the resistance above 1.0 Ohm?
  
  Yes
  - Repair the (C21) Evaporator Temperature Sensor Signal circuit for an open.
  - Perform HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Go To 5.
CHECK THE (C121) SENSOR GROUND CIRCUIT FOR AN OPEN

Fig 4: Checking Evaporator Temperature Sensor Ground Or An Open
Courtesy of CHRYSLER GROUP, LLC
1. Measure the resistance of the (C121) Sensor Ground circuits between the A/C Heater Control C1 harness connector and the Evaporator Temperature Sensor harness connector.
  NOTE:
  There are two C121 terminals in the A/C Heater Control C1 harness connector. Make sure to check both.
  
  Is the resistance above 1.0 Ohm?
  
  Yes
  - Repair the (C121) Sensor Ground circuit for an open.
  - Perform HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Go To 6.
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 .
3. Cycle the ignition off for 30 seconds then back on and wait a minimum of 60 seconds.
4. With the Scan tool read HVAC DTC's.
  Does this DTC reset?
  
  Yes
  - Replace and program 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. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, partially broken wires.
4. Check the connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals.
5. Wiggle the wiring and connectors while checking for shorted and open circuits.
6. With the scan tool, check the Environmental Data to help identify the conditions in which the DTC was set.
  Were there any problems found?
  
  Yes
  - Repair as necessary.
  - Perform HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Test complete.