Diagnostic Instructions

DTC Descriptors

DTC P0532: Air Conditioning (A/C) Pressure Sensor Circuit Low Voltage

DTC P0533: Air Conditioning (A/C) Pressure Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
5-Volt Reference Circuit	P0532	P0532	P0533	--
Low Reference Circuit	--	P0533	--	--
Signal Circuit	P0532	P0532	P0533	--

Circuit/System Description

The engine control module (ECM) monitors the high side refrigerant pressure through the A/C refrigerant pressure sensor. The ECM supplies a 5-volt reference and a low reference to the sensor. Changes in the A/C refrigerant pressure causing the A/C refrigerant pressure sensor signal to the ECM to vary. When the pressure is high, the signal voltage is high. When the pressure is low, the signal voltage is low. When pressure is high, the ECM commands the cooling fans ON. When pressure is too high or too low, the ECM will not allow the A/C compressor clutch to engage.

Conditions for Running the DTC

Conditions for Setting the DTC

P0532

The ECM detects that the A/C pressure is less than 0 psi.

P0533

The ECM detects that the A/C pressure is more than 428 psi.

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Diagnostic Aids

Test the following conditions:

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, with the engine OFF. Observe the scan tool A/C Refrigerant Pressure parameter. The reading should be between 4.8-5.2 volts and change with A/C pressure.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the A/C refrigerant pressure sensor.
2. Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal 1 and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and ground.

⇒	If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Verify the scan tool A/C Refrigerant Pressure parameter is greater than 5.2 volts.

⇒	If less than the specified range, test the signal circuit terminal for a short to ground. If the circuit tests normal, replace the ECM.

5. Install a 3-amp fused jumper wire between the signal circuit terminal 3 and the low reference circuit terminal 1. Verify the scan tool A/C Refrigerant Pressure parameter is less than 4.8 volt.

⇒	If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

6. If the circuit tests normal, replace the A/C refrigerant pressure sensor.

Component Testing

1. Install a 3-amp fused jumper harness between the 5-volt reference circuit terminal 2 and 5 volts. Install a jumper wire between the low reference terminal 1 and ground.
2. Sweep the sensor through the entire range while monitoring the voltage between the signal terminal 3 and the low reference terminal 1. The voltage should vary between 4.8 and 5.2 volts without any spikes or dropouts.

⇒	If the voltage is not within the specified range or is erratic, replace the A/C refrigerant pressure sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.