B1030-12-EVAPORATOR TEMPERATURE SENSOR - CIRCUIT SHORT TO BATTERY

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The HVAC A/C heater control uses a variety of sensors to adjust HVAC operation to obtain optimal performance. These sensors are continuously monitored by the A/C heater control to assure that they are in range. An active Diagnostic Trouble Code (DTC) indicates that a sensor is out of range. A stored DTC indicates that the sensor was out of range but is currently within range.

The evaporator temperature sensor monitors the surface temperature of the A/C evaporator and supplies an input signal to the A/C heater control. The input signal value is used to optimize the A/C system performance and to protect the A/C evaporator from freezing. The evaporator temperature sensor resistance value will change in response to the surface temperature of A/C evaporator. The resistance value is electronically transferred to the A/C heater control using a sensor ground circuit and a 5-volt reference signal circuit. Normal operation of the sensor the resistive value decreases when the A/C evaporator temperature decreases and the sensor resistive value increases when the A/C evaporator temperature increases.

• When Monitored:

  With the ignition on.

• Set Condition:

  The Evaporator Temperature Sensor voltage input to the A/C Heater Control is equal to or above 4.8 volts for a continuous period of two seconds. If the A/C Heater Control detects a valid voltage, the DTC will change from Active to Stored and will stay in the controllers memory for 100 ignition cycles.

Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/HVAC - Standard Procedure) .

1. CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT VOLTAGE

• Go To 2

• Go To 7

2. CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT VOLTAGE

• Replace the Evaporator Temperature Sensor in accordance with the Service Information. (Refer to 24 - Heating and Air Conditioning/Controls/SENSOR, Evaporator Temperature - Removal) .
• Perform the HVAC VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/HVAC - Standard Procedure) .

• Go To 3
  

3. CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE

• Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to voltage.
• Perform the HVAC VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/HVAC - Standard Procedure) . 

• Go To 4
  

4. CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR AN OPEN

• Repair the (C21) Evaporator Temperature Sensor Signal circuit for an open or high resistance.
• Perform the HVAC VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/HVAC - Standard Procedure) .

• Go To 5
  

5. CHECK THE (C121) SENSOR GROUND CIRCUIT FOR AN OPEN

• Repair the (C121) Sensor Ground circuit for an open.
• Perform the HVAC VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/HVAC - Standard Procedure) .

• Go To 6

6. CHECK THE EVAPORATOR TEMPERATURE SENSOR

• Replace and program the A/C Heater Control in accordance with the Service Information. (Refer to 24 - Heating and Air Conditioning/Controls/CONTROL, A/C and Heater - Removal) .
• Perform the HVAC VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/HVAC - Standard Procedure) .

• Test complete.
• Perform the HVAC VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/HVAC - Standard Procedure) .

7. CHECK THE WIRING AND CONNECTORS

• Repair as necessary.
• Perform the HVAC VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/HVAC - Standard Procedure) .

• Test complete.