B1030-15

B1030-15-EVAPORATOR TEMPERATURE SENSOR - CIRCUIT SHORT TO BATTERY OR OPEN





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

Theory of Operation

The Evaporator Temperature Sensor is a variable resistor that changes in conjunction with temperature, or otherwise known as a thermistor. The Evaporator Temperature Sensor is located in the HVAC housing downstream of the A/C evaporator. The A/C Heater Module monitors the evaporator temperature by monitoring the voltage change of the Evaporator Temperature Sensor Signal circuit. If the monitored voltage drops below or rises above a predetermined voltage, a Diagnostic Trouble Code (DTC) will set. For further information Evaporator Temperature Sensor - Operation.

- When Monitored:
With the ignition on.

- Set Condition:
The A/C Heater Module detects greater than 4.8 volts on the Evaporator Temperature Sensor Signal circuit for a period of two seconds or more. If the A/C Heater Module detects a valid voltage, the DTC will change from active to stored and will stay stored for 100 ignition cycles.





Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.

1. CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT VOLTAGE
1. Ignition on, engine not running.
2. With the scan tool, read HVAC DTCs.

Is this DTC active?

Yes

- Go To 2

No

- Go To 6

2. CHECK THE EVAPORATOR TEMPERATURE SENSOR




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. Evaporator Temperature Sensor - Removal.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Go To 3

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




1. Turn the ignition off to the lock position.
2. Disconnect the jumper wire from the previous step.
3. Disconnect the A/C Heater Module 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 the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Go To 4

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




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 Module 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 the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Go To 5

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




1. Measure the resistance of the (C121) Sensor Ground circuit between the A/C Heater Module C1 harness connector and the Evaporator Temperature Sensor harness connector.

Is the resistance above 1.0 Ohm?

Yes

- Repair the (C121) Sensor Ground circuit for an open.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Replace and program the A/C Heater Module. A/C And Heater Control Module - Removal.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

6. 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 wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
4. Wiggle the wiring and connectors while checking for shorted and open circuits.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Test complete.