For 1990-2009 cars

### Circuit Description

The A/C system uses an A/C refrigerant pressure sensor mounted in the high side of the A/C system to monitor A/C refrigerant pressure. The PCM utilizes this information to turn ON the engine coolant fans when the A/C refrigerant pressure is high.

The A/C refrigerant pressure sensor operates much like other 3-wire sensors. A 5.0 volt reference is supplied to the sensor and returned to the PCM on the signal circuit. As A/C pressure increases or decreases, the resistance of the sensor changes and varies the amount of signal returning to the PCM.

The PCM monitors the A/C refrigerant pressure sensor signal circuit and can determine when A/C pressure is too high or too low. When pressures are out of range (high or low) for a predetermined time, the PCM will disable the A/C compressor clutch and set a DTC P0530. When a DTC P0530 is set, the PCM will disable the A/C compressor clutch so compressor damage does not occur.

### Conditions for Setting the DTC

• | A/C refrigerant pressure sensor indicates A/C refrigerant pressure is below -8.0 psi for 5.0 seconds.

• | A/C refrigerant pressure sensor indicates A/C refrigerant pressure is above 448 psi for 5.0 seconds.

### Action Taken When the DTC Sets

• | The DTC will be stored in the PCM memory when the diagnostic runs and fails.

• | The Malfunction Indicator Lamp (MIL) will not illuminate.

• | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in Failure Records.

### Conditions for Clearing the MIL/DTC

• | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.

• | A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.

• | PCM battery voltage is interrupted.

• | Using a scan tool.

### Diagnostic Aids

If the test did not fail this ignition cycle, move related electrical harnesses and connectors while monitoring a scan tool.

For intermittents, refer to Symptoms .

### Test Description

Number(s) below refer to step numbers on the diagnostic table.

1. Normal A/C voltage is between 1 and 1.8 volts. If A/C voltage is within range, review freeze frame data to determine when DTC P0530 set.

2. If A/C pressure/voltage stays high after disconnecting the A/C refrigerant pressure sensor electrical connector, indicates the signal circuit is shorted to a voltage.

3. Checks for a good ground circuit.

4. Checks the integrity of A/C refrigerant pressure sensor signal circuit.

5. If the 5 volt reference circuit has been checked thoroughly (for opens, shorts too ground, PCM connections etc.) and checks OK, then replace the PCM.

6. If the ground circuit has been checked thoroughly for opens and PCM connections are OK, then replace the PCM.

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

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn the ignition ON, engine OFF.
2. Using a scan tool, monitor A/C High Side.

Does the scan tool indicate A/C High Side between the specified values?

0.1 V to 1.8 V

Go to Step 3

Go to Step 4

3 |

1. Turn the ignition ON, engine OFF, review freeze frame data and note parameters.
2. Operate the vehicle within freeze frame conditions as noted.

Did the test fail this ignition cycle while operating the vehicle in the conditions that were noted?

--

Go to Step 4

Go to Diagnostic Aids

4 | Disconnect the A/C refrigerant pressure sensor electrical connector. Does the scan tool indicate the A/C High Side less than the specified value? | 1.0 V | Go to Step 5 | Go to Step 9
5 | Using a DVM (J 39200), measure voltage from the A/C refrigerant pressure sensor 5.0 volt reference circuit to battery ground. Does the DVM indicate voltage at the specified value? | 5.0 V | Go to Step 6 | Go to Step 10
6 | Using a DVM (J 39200), measure voltage from the A/C refrigerant pressure sensor 5.0 volt reference circuit to sensor ground circuit. Does the DVM indicate voltage at the specified value? | 5.0 V | Go to Step 7 | Go to Step 11
7 | Using a jumper wire, jumper 5.0 volt reference circuit to A/C refrigerant pressure sensor signal circuit. Does the scan tool indicate the A/C High Side at the specified value? | 5.0 V | Go to Step 8 | Go to Step 12
8 | Repair the faulty A/C refrigerant pressure sensor connection or faulty sensor. Is the action complete? | -- | Go to Step 13 | --
9 | Repair the A/C refrigerant pressure sensor signal circuit shorted to voltage. Is the action complete? | -- | Go to Step 13 | --
10 | Repair 5.0 volt reference circuit to A/C refrigerant pressure sensor. Is the action complete? | -- | Go to Step 13 | --
11 | Repair ground circuit to A/C refrigerant pressure sensor. Is the action complete? | -- | Go to Step 13 | --
12 | Repair signal circuit to A/C refrigerant pressure sensor. Is the action complete? | -- | Go to Step 13 | --
13 |

1. Using the scan tool, select DTC, Clear Info.
2. Start the engine and idle at normal operating temperature.
3. Select DTC, Specific, then enter the DTC number which was set.
4. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 14

Go to Step 2

14 | Using the scan tool, select Capture Info, Review Info. Are any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK