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.
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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.
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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.
-
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.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||
|
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 | |||||||||
3 | Does the scan tool indicate voltage more than the specified value? | 4.2V | Go to Diagnostic Aids | |||||||
Does the scan tool indicate voltage at or near the specified value? | 0V | |||||||||
5 |
Does the scan tool indicate voltage at or near the specified value? | 5V | ||||||||
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 | ||||||||
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? | -- | ||||||||
8 | Test for the following conditions:
Did you find a problem? | -- | ||||||||
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? | -- | ||||||||
10 | Test the A/C refrigerant pressure signal circuit for an open or short to ground. Did you find a problem? | -- | ||||||||
11 | Test the A/C refrigerant pressure signal circuit for a short to voltage. Did you find a problem? | -- | ||||||||
12 | Test for a short to voltage on the 5 volt reference B circuit. Did you find a problem? | -- | ||||||||
13 | Inspect the ground circuit for a poor connection at the PCM. Refer to Intermittents and Poor Connections Diagnosis . Did you find a problem? | -- | ||||||||
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? | -- | ||||||||
15 | Test for an open or a faulty splice in the sensor ground circuit. Did you find a problem? | -- | ||||||||
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? | -- | ||||||||
17 | Repair the faulty connection. Refer to Connector Repairs . Did you complete the repair? | -- | -- | |||||||
18 | Repair the open or short as necessary. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |||||||
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? | -- | -- | |||||||
|
Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement? | -- | -- | ||||||||
21 |
Does the scan tool indicate voltage between the specified values? | 0.1-4.8V | System OK |
