For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Strategy Based Diagnosis

• | Diagnostic Procedure Instructions

### DTC Descriptor

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
--- | --- | --- | ---
5 -Volt Reference Circuit | P0532 | P0532 | P0533
A/C Refrigerant Pressure Sensor Signal Circuit | P0532 | P0533 | P0532
Low Reference Circuit | -- | 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 cause the A/C refrigerant pressure sensor signal to the ECM to vary. When the pressure is low, the signal voltage is low. When the 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

• | The Engine is running.

• | The Battery voltage is between 11 -- 18 volts.

### Conditions for Setting the DTC

• | The ECM detects that the A/C pressure is less than 1psi (0.01 volts).

• | The ECM detects that the A/C pressure is more than 425 psi (4.90 volts).

### 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 or DTC's can be cleared by using the scan tool.

• | 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

HVAC Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

• | Scan Tool Output Controls

• | Scan Tool Data List

### Circuit/System Verification

Ignition ON, observe the scan tool A/C High Side Pressure parameter in the ECM. The reading should be between 0.1 and 4.90 volts (1 and 425 psi), and change with pressure.

### Circuit/System Testing

1. Ignition OFF, disconnect the A/C Refrigerant Pressure 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 and ground.

⇒ | If greater than 1.0 ohm, 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 and ground.

⇒ | If less than 4.8 volts, 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 5.2 volts, 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 High Side Pressure Sensor parameter is less than 0.1 volts (1 psi).

⇒ | If greater than 0.1 volts (1 psi), test the signal circuit terminal for a short to voltage. If the circuit tests normal, replace the ECM.

5. Install a 3-amp fused jumper wire between the signal circuit and the 5-volt reference circuit terminal. Verify the scan tool A/C Refrigerant High Side Pressure Sensor is greater than 4.90 volts (425 psi).

⇒ | If less than 4.90 volts (425 psi), test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

6. If all circuits test normal, replace the A/C Refrigerant Pressure Sensor.

### Repair Instructions

Important: Always perform Diagnostic Repair Verification after completing the diagnostic procedure.

• | Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement

• | Control Module References for the ECM setup, replacement, and programming.