For 1990-2009 cars
Engine Controls Components
A/C HVAC Control
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 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 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.

| OR

• | The A/C refrigerant pressure sensor signal voltage is greater than 4.9 volts.

Either of the conditions are present for longer than 20 seconds.

### Action Taken When the DTC Sets

• | The PCM will not illuminate the malfunction indicator lamp (MIL).

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

### Conditions for Clearing the MIL/DTC

• | A History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | The DTC can be cleared by using the scan tool Clear Info function.

### Diagnostic Aids

Check for the following conditions:

Important:: Be sure to inspect PCM engine grounds for being secure and clean.

Poor connection at PCM - Inspect harness connectors for the following items:

• | Backed out terminals

• | Improper mating

• | Broken locks

• | Improperly formed or damaged terminals

• | Poor terminal to wire connections

• | Damaged harness - Inspect the wiring harness for damage.

• | If the harness appears to be OK, observe the A/C pressure display on the scan tool while moving connectors and wiring harnesses related to the A/C refrigerant pressure sensor. A change in the A/C pressure display will indicate the location of the fault.

If DTC P0530 cannot be duplicated, review the Freeze Frame/Fail Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. Normal A/C pressure sensor signal voltage is between 0.1 and 4.8 volts. If A/C voltage is within range, review Fail Recordsto determine the conditions that were present when DTC P0530 set.

2. 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.

3. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.

#### DTC P0530 - A/C Refrigerant Pressure Sensor Circuit

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Important: If DTC P1639 is set, refer to DTC P1639 5 Volt Reference 2 Circuit first. With a scan tool, observe the A/C refrigerant pressure sensor voltage parameter. Does the scan tool indicate voltage less than the specified value? | 0.1V | Go to Step 5 | Go to Step 3
3 | Does the scan tool indicate voltage more than the specified value? | 4.2V | Go to Step 4 | Go to Diagnostic Aids
4 |

1. Disconnect the A/C refrigerant pressure sensor.
2. With a scan tool, observe the A/C refrigerant pressure sensor voltage parameter

Does the scan tool indicate voltage at or near the specified value?

0V

Go to Step 12

Go to Step 11

5 |

1. Disconnect the A/C refrigerant pressure sensor.
2. Connect a fused jumper between the A/C refrigerant pressure signal circuit and the 5 volt reference B circuit.
3. With a scan tool, observe A/C refrigerant pressure sensor voltage parameter.

Does the scan tool indicate voltage at or near the specified value?

5V

Go to Step 16

Go to Step 6

6 | Connect a J 39200 Digital Multimeter between the 5 volt reference B circuit and the ground circuit. Does the voltage measure at or near the specified value? | 5V | Go to Step 9 | Go to Step 7
7 | Inspect the 5 volt reference B circuit for a poor connection at the PCM. Refer to Intermittents and Poor Connections Diagnosis . Did you find a problem? | -- | Go to Step 17 | Go to Step 8
8 | Test for the following conditions:

• | A short to ground in the 5 volt reference B circuit.

• | An open in the 5 volt reference B circuit.

• | A faulty splice in the 5 volt reference B circuit.

Did you find a problem?

--

Go to Step 18

Go to Step 13

9 | Inspect the A/C refrigerant pressure signal circuit for a poor connection at the PCM. Refer to Intermittents and Poor Connections Diagnosis Did you find a problem? | -- | Go to Step 17 | Go to Step 10
10 | Test the A/C refrigerant pressure signal circuit for an open or short to ground. Did you find a problem? | -- | Go to Step 18 | Go to Step 20
11 | Test the A/C refrigerant pressure signal circuit for a short to voltage. Did you find a problem? | -- | Go to Step 18 | Go to Step 20
12 | Test for a short to voltage on the 5 volt reference B circuit. Did you find a problem? | -- | Go to Step 18 | Go to Step 13
13 | Inspect the ground circuit for a poor connection at the PCM. Refer to Intermittents and Poor Connections Diagnosis . Did you find a problem? | -- | Go to Step 17 | Go to Step 14
14 | Inspect the ground circuit for a poor connection at the A/C refrigerant pressure sensor. Refer to Intermittents and Poor Connections Diagnosis . Did you find a problem? | -- | Go to Step 17 | Go to Step 15
15 | Test for an open or a faulty splice in the sensor ground circuit. Did you find a problem? | -- | Go to Step 18 | Go to Step 19
16 | Inspect the 5 volt reference B circuit or A/C refrigerant pressure signal circuit for a poor connection at the A/C refrigerant pressure sensor. Refer to Intermittents and Poor Connections Diagnosis . Did you find a problem? | -- | Go to Step 17 | Go to Step 19
17 | Repair the faulty connection. Refer to Connector Repairs . Did you complete the repair? | -- | Go to Step 21 | --
18 | Repair the open or short as necessary. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 21 | --
19 | Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement in HVAC. Did you complete the replacement? | -- | Go to Step 21 | --
20 | Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement? | -- | Go to Step 21 | --
21 |

1. Turn ON the ignition.
2. Use the scan tool in order to clear DTCs.
3. With a scan tool, observe the A/C refrigerant pressure sensor voltage parameter.

Does the scan tool indicate voltage between the specified values?

0.1-4.8V

System OK

Go to Step 2