GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    •  Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    •  Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of the diagnostic category.

DTC Descriptors

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

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

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

A/C Refrigerant Low Pressure Switch Signal

P0532

P0532

P0533

--

Low Reference

--

P0533

--

--

Circuit/System Description

The A/C low pressure switch protects the A/C system. The A/C low pressure switch is a 2-wire normally closed switch. The A/C low pressure switch opens the A/C low pressure switch signal circuit and disables the A/C compressor when line pressure falls below 152 kPa (22 psi). The switch will then close once the pressure reaches 303 kPa (44 psi).

Conditions for Running the DTC

    • Engine is running.
    • Any of the conditions for setting the DTC are met for 15 seconds.
    • Battery voltage is between 11-18 volts.

Conditions for Setting the DTC

The ECM detects that the A/C pressure is less than 152 kPa (22 psi).

Action Taken When the DTC Sets

    • The ECM will not illuminate the malfunction indicator lamp (MIL)
    • The ECM stores the Failure Records.
    • The A/C compressor clutch is disabled.

Conditions for Clearing the DTC

    • The history DTC will clear after 40 consecutive ignition cycles have occurred without a malfunction.
    • The DTC will become history if the ECM no longer detects a failure.

Diagnostic Aids

A malfunction within the refrigerant system causing high pressure can cause this DTC to set.

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

    •  Air Temperature Description and Operation
    •  Air Delivery Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

  1. Ignition OFF, disconnect the A/C pressure switch harness connector.
  2. Ignition OFF, test for less than 1 ohm between the ground circuit and ground.
  3. If greater than 1 ohm, test the ground circuit for an open/high resistance.
  4. Install a 3-amp fused jumper wire between the signal circuit and the ground circuit. Verify the scan tool Pressure Switch parameter is Low Pressure.
  5. If not the specified value, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  6. If all circuits test normal, test or replace the A/C Pressure switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Air Conditioning Cycling Switch Replacement
    •  Air Conditioning (A/C) High Pressure Switch Replacement
    •  Control Module References for ECM replacement, setup, and programming