Ambient Temperature Sensor / Switch HVAC: Testing and Inspection

The ambient temperature sensor can be diagnosed using the following Sensor Test, and Sensor Circuit Test. If the temperature sensor and circuit are confirmed to be OK, but the temperature display is inoperative or incorrect, replace the compass/temperature display.

SENSOR TESTING
1. Turn the ignition switch to the OFF position. Disconnect and isolate the battery negative cable. Disconnect the ambient temperature sensor wire harness connector.
2. Measure the resistance of the ambient temperature sensor. At room temperature (approx. 68°F), the sensor resistance should be between 9-11 Kiloohms (9000-11000 ohms). The sensor resistance should read between these two values. If OK, refer to Sensor Circuit Testing below. If not OK, replace the faulty ambient temperature sensor.

SENSOR CIRCUIT TESTING
1. Turn the ignition switch to the OFF position. Disconnect and isolate the battery negative cable. Disconnect the ambient temperature sensor wire harness connector and the NGC engine controller wire harness connector.
2. Connect a jumper wire between the two terminals in the body half of the ambient temperature sensor wire harness connector.
3. Check for continuity between the sensor return circuit and the ambient temperature sensor signal circuit cavities of the NGC engine controller wire harness connector. There should be continuity. If OK, go to Step 4. If not OK, repair the open sensor return circuit or ambient temperature sensor signal circuit to the ambient temperature sensor as required.
4. Remove the jumper wire from the body half of the ambient temperature sensor wire harness connector. Check for continuity between the sensor return circuit cavity of the NGC engine controller wire harness connector and a good ground. There should be no continuity. If OK, replace the compass/ temperature display unit. If not OK, repair the shorted sensor return circuit as required.