Code 71, A/C Temperature (Circuit Open Or Shorted): Notes

The A/C system uses an A/C evaporator temperature sensor mounted in the A/C evaporator core to monitor A/C temperature for use by the PCM. The PCM uses this information to cycle the A/C compressor clutch so optimum cooling is attained. This will also prevent evaporator core freezing. The PCM will disable the A/C compressor clutch when A/C evaporator temperature is less than 36°F (2°C). A Code 71 will set under improper operating conditions; however, SERVICE ENGINE SOON light will not illuminate.

1. Code 71 will set if A/C is requested and the PCM detects an open, short to ground or short to voltage in the evaporator temperature sensor circuit. All conditions must be met for 3 seconds for code to be set.
2. With A/C evaporator sensor disconnected, normal voltage on circuit is near 5 volts. If a short to voltage is suspected, reconnect sensor harness and backprobe terminal "B" of sensor harness using a DVOM. If 5 volts or more is indicated, circuit is shorted to voltage.