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B1916-15






B1916-15-EVAPORATOR TEMPERATURE SENSOR - CIRCUIT SHORT TO BATTERY OR OPEN





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. Initial Inspection and Diagnostic Overview.

1. CHECK (C) 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 7

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. Ignition on, engine not running.
4. Measure the voltage between the (C) Evaporator Temperature Sensor Signal circuit and the (CC) Sensor Ground circuit in the Evaporator Temperature Sensor harness connector.

Is the voltage below 0.1 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 (C) 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 Evaporator Temperature Sensor harness connector.
3. Disconnect the A/C Heater Control harness connector.
4. Ignition on, engine not running.
5. Measure the voltage of the (C) Evaporator Temperature Sensor Signal circuit.

Is there any voltage present?

Yes

- Repair the (C) 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 (C) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR AN OPEN




1. Turn the ignition off to the lock position.
2. Measure the resistance of the (C) Evaporator Temperature Sensor Signal circuit between the A/C Heater Control harness connector and the Evaporator Temperature Sensor harness connector.

Is the resistance above 1.0 Ohm?

Yes

- Repair the (C) Evaporator Temperature Sensor Signal circuit for an open or high resistance.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Go To 5

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




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

Is the resistance above 1.0 Ohm?

Yes

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

No

- Go To 6

6. CHECK THE EVAPORATOR TEMPERATURE SENSOR
1. Replace the Evaporator Temperature Sensor. Evaporator Temperature Sensor - Removal.
2. Cycle the ignition off for 30 seconds then back on.
3. With the scan tool, read HVAC DTCs.

Does this DTC reset?

Yes

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

No

- Test complete.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

7. 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.

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