Code 71, Low A/C Temperature: Notes

A/C temperature sensor is mounted to the evaporator, located within the instrument panel. The PCM receives a voltage signal inversely proportional to the temperature at the evaporator coils. As the evaporator temperature increases or decreases, the resistance of the sensor changes and varies the voltage signal to the PCM. This voltage is converted to a temperature value by the PCM and can then be displayed in degrees on a scan tester. A Code 71 fault will be stored in the PCM when evaporator temperature is less than -7°C but will not illuminate the SERVICE ENGINE SOON light.

1. Code 71 will set if A/C evaporator temperature sensor indicates less than -7°C and time since start is 5 seconds or more.