P0533

Diagnostic Chart:

Schematic:

The air conditioning (A/C) pressure sensor is a transducer that varies resistance according to changes in A/C high side refrigerant pressure. The ECM measures the signal voltage from the A/C pressure sensor, which is a reduced value of the ECM 5 volt reference. The voltage range of the sensor is around 0.25-4.75 volts (101-3400 kPa absolute), 14.7-493 psi absolute. The sensor input is primarily used by the ECM to determine acceptable low/high refrigerant levels for safe A/C operation, A/C idle speed control and for cooling fan control during A/C operation. DTC P0533 will set if the A/C pressure sensor signal voltage at the ECM is above the calibrated voltage value.

DTC PARAMETERS
DTC P0533 will set if A/C pressure sensor signal voltage is greater than 4.88 volts when:
^ Condition exists for longer than 3 seconds
^ Engine speed is running

DTC P0533 diagnostic runs continuously with engine running.

P0533 is a type D DTC.

DIAGNOSTIC AIDS
To locate an intermittent problem, use Scan tool to monitor AC PRESSURE SENSOR voltage with ignition On, engine Off. Wiggling wires while monitoring AC PRESSURE SENSOR voltage may locate the area where an open or short to voltage in the wiring may exist.

The A/C pressure sensor may contain an intermittent open, which may set this DTC. Run engine and operate A/C while using Scan tool to monitor AC PRESSURE SENSOR.

Circuit 2760 (MAF sensor), circuit 2709 (AC pressure/fuel tank pressure sensor) and circuit 1164 (APP sensor 1) share the same 5 volt reference supply (5 volt Ref-A).

NOTE:
^ If the sensor return circuit 2751 is open, AC PRESSURE SENSOR voltage on Scan tool will read near 3.72 volts with the A/C relay commanded Off. This condition may or may not set this DTC.
^ A/C HIGH SIDE PRESSURE On Scan tool is in absolute pressure like that of a MAP sensor.

IMPORTANT: Inaccurate readings will occur if resistance measurements are taken on an A/C pressure sensor. The A/C pressure sensor contains an internal amplifier circuit that requires applied voltage to function properly.