For 1990-2009 cars
Engine Controls Components
Engine Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The A/C system uses an A/C refrigerant pressure sensor mounted in the high pressure side of the A/C refrigerant system to monitor A/C refrigerant pressure. The powertrain control module (PCM) uses this information to turn ON the engine coolant fans when the A/C refrigerant pressure is high and to keep the compressor disengaged when A/C refrigerant pressure is excessively high or low. The A/C refrigerant pressure sensor operates like other 3-wire sensors. The PCM applies a 5.0 volt reference and a sensor ground to the sensor. Changes in the A/C refrigerant pressure will cause the A/C refrigerant pressure input to the PCM to vary. The PCM monitors the A/C refrigerant pressure signal circuit and can determine when the signal is outside of the possible range of the sensor. When the signal is out of range, high or low, for a prolonged period of time, the PCM will set DTC P0530. When DTC P0530 is set, the PCM will not allow the A/C compressor clutch to engage. This is done to protect the compressor.

### Conditions for Running the DTC

• | The engine is running.

• | A/C is requested.

### Conditions for Setting the DTC

The A/C refrigerant pressure sensor signal voltage is less than 0.1 volt (9 psi).

OR

• | The A/C refrigerant pressure sensor signal voltage is more than 4.9 volts (472 psi).

• | Either of the above conditions are present for more than 20 seconds.

### Action Taken When the DTC Sets

The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.

### Conditions for Clearing the MIL/DTC

• | The DTC becomes history when the conditions for setting the DTC are no longer present.

• | The history DTC clears after 40 malfunction free warm-up cycles.

• | The PCM receives a clear code command from the scan tool.

### Diagnostic Aids

Inspect for the following conditions:

Many situations may lead to an intermittent condition. Perform each inspection or test as directed.

Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

• | Loose terminal connection

- | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.

- | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.

• | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

• | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.

### Test Description

The numbers below refer to the step numbers on the diagnostic table:

1. If the A/C refrigerant pressure signal voltage stays high after disconnecting the A/C refrigerant pressure sensor electrical connector, the signal circuit is shorted to voltage or the PCM is faulty.

2. Tests for a high resistance or an open in the ground circuit.

3. This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read only memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn ON the ignition, with the engine OFF.
2. With a scan tool, observe the A/C pressure sensor parameter.

Does the scan tool indicate that the A/C pressure sensor parameter is within the specified range?

0.1 V to 4.9 V

Go to Diagnostic Aids

Go to Step 3

3 |

1. Turn OFF the ignition.
2. Disconnect the A/C pressure sensor
3. Turn ON the ignition, with the engine OFF.
4. With a scan tool, observe the A/C pressure sensor parameter.

Does the scan tool indicate that the A/C pressure sensor parameter is less than the specified value?

0.1V

Go to Step 4

Go to Step 10

4 |

1. Turn OFF the ignition.
2. Connect a 3 amp fused jumper wire between the 5 volt reference B circuit of the A/C pressure sensor and the signal circuit of the A/C pressure sensor .
3. Turn ON the ignition, with the engine OFF.
4. With a scan tool, observe the A/C pressure sensor parameter.

Does the scan tool indicate that the A/C pressure sensor parameter is more than the specified value?

4.9 V

Go to Step 5

Go to Step 8

5 |

1. Disconnect the fused jumper wire.
2. Measure the voltage between the 5 volt reference B circuit of the A/C pressure sensor and the ground circuit of the A/C pressure sensor.

Does the voltage measure less than the specified value?

5.1 V

Go to Step 6

Go to Step 7

6 |

1. Turn OFF the ignition.
2. Measure the resistance from the ground circuit of the A/C pressure sensor to a good ground.

Does the resistance measure less than the specified value?

5 ohms

Go to Step 12

Go to Step 11

7 | Test the 5 volt reference B circuit of the A/C pressure sensor for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13
8 | Test the 5 volt reference B circuit of the A/C pressure sensor for a short to ground, high resistance, or an open. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 9
9 | Test the signal circuit of the A/C pressure sensor for a short to ground, high resistance, or an open. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13
10 | Test the signal circuit of the A /C pressure sensor for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13
11 |

1. Disconnect the PCM.
2. Test the ground circuit of the A/C pressure sensor for high resistance or an open. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

12 | Inspect for poor connections at the harness connector of the A/C pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 14
13 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 15
14 | Replace the A/C pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement in HVAC. Did you complete the replacement? | -- | Go to Step 16 | --
15 | Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Step 16 | --
16 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK