P1535

Circuit Description
The Air Conditioning (A/C) high side temperature sensor uses a thermistor to control the signal voltage to the PCM. The PCM applies 5 volts on CKT 732 to the sensor. When the sensor is cold, its resistance is high; therefore, the PCM will see a high signal voltage. As the sensor warms, its resistance becomes less and the signal voltage is pulled low through the ground, CKT 1704. This diagnostic detects a shorted to ground or open A/C high side temperature sensor circuit by setting the DTC if the PCM monitors a signal voltage, temperature, that is too high or low.

Conditions for Running the DTC
^ Ambient Air Temperature between 40°F and 210°F.
^ Ambient Air Temperature sensor failure not indicated by the HVAC controller.

Conditions for Setting the DTC
A/C high temperature sensor reads less than 12°C (10°F) or more than 210°C (410°F).

Action Taken When the DTC Sets
Enable cooling fans to high if A/C clutch engagement is possible.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ No message will be displayed.

Conditions for Clearing the DTC
^ A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test.
^ A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
^ Use a scan tool to clear DTCs.
^ Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended.

Diagnostic Aids
With the vehicle engine not running and at ambient temperature the A/C temperature sensor should also be near ambient temperature. If the A/C temperature sensor is not near ambient temperature check for a sensor or circuit with resistance that is too high or too low. A sensor temperature reading that is too high would indicate a shorted or low resistance sensor or circuit. A sensor temperature reading that is too low would indicate an open or high resistance sensor or circuit.