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 signal input to the PCM to vary. The PCM monitors the A/C refrigerant pressure 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 above conditions is present for more 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 Fail Records data only. This information will not be stored as Freeze Frame data. |
| • | A/C compressor operation will be disabled while the high or low pressure indication exists. |
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:
| • | Poor connection at the PCM or the A/C refrigerant pressure sensor |
| Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Damaged harness |
| Inspect the wiring harness for damage. If the harness appears to be OK, observe the A/C High Side 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 High Side Pressure display will indicate the location of the malfunction. |
Important: Be sure to inspect PCM engine grounds for being secure and clean.
If DTC P0530 cannot be duplicated, reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Test Description
The numbers below refer the step numbers on the diagnostic table.
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Normal A/C refrigerant pressure sensor signal voltage is between 0.1 and 4.8 volts. If A/C voltage is within range, review Fail Records data to 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 malfunctioning.
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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. Refer to PCM Replacement/Programming .
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
If P1639 is also set, perform DTC P1639 5 Volt Reference 2 Circuit first. Observe A/C High Side Pressure displayed on the scan tool. Is A/C High Side Pressure less than the specified value? | 0.1 V | |||
3 | Is A/C High Side Pressure greater than the specified value? | 4.8 V | Go to Diagnostic Aids | |
Disconnect the A/C refrigerant pressure sensor while observing A/C High Side Pressure on the scan tool. Does the scan tool indicate voltage near the specified value? | 0 V | |||
5 |
Does the scan tool indicate A/C High Side Pressure near the specified value? | 5 V | ||
6 | Using a J 39200 Digital Multimeter, measure voltage between the 5 volt reference B circuit and the sensor ground circuit at the A/C refrigerant pressure sensor harness connector. Is voltage near the specified value? | 5 V | ||
7 | Check for a poor 5 volt reference B circuit terminal connection at the PCM. Refer to Intermittents and Poor Connections Diagnosis . Was a problem found? | -- | ||
8 | Check for an open or a short to ground in the 5 volt reference B circuit. Refer to Wiring Repairs . Was a problem found? | -- | ||
9 | Check the A/C refrigerant pressure signal circuit for a poor terminal connection at the PCM. Refer to Intermittents and Poor Connections Diagnosis . Was a problem found? | -- | ||
10 | Check the A/C refrigerant pressure signal circuit between the A/C refrigerant pressure sensor connector and the PCM for an open or short to ground. Refer to Wiring Repairs . Was a problem found? | -- | ||
11 | Check the A/C refrigerant pressure signal circuit between the A/C refrigerant pressure sensor connector and the PCM for a short to voltage. Refer to Wiring Repairs . Was a problem found? | -- | ||
12 | Check for a short to voltage on the 5 volt reference B circuit. Refer to Wiring Repairs . Was a problem found? | -- | ||
13 | Check for a poor sensor ground circuit terminal connection at the PCM. Refer to Intermittents and Poor Connections Diagnosis . Was a problem found? | -- | ||
14 | Check for a poor sensor ground circuit terminal connection at the A/C refrigerant pressure sensor connector. Was a problem found? | -- | ||
15 | Check for an open in the sensor ground circuit. Refer to Ground Distribution Schematics . Was a problem found? | -- | ||
16 | Check for a poor 5 volt reference B circuit or A/C refrigerant pressure signal circuit terminal connection at the A/C refrigerant pressure sensor. Refer to Intermittents and Poor Connections Diagnosis . Was a problem found? | -- | ||
17 | Replace the malfunctioning harness connector terminal. Refer to Repairing Connector Terminals . Is the action complete? | -- | -- | |
18 | Locate and repair open/short circuit in wiring harness as necessary. Refer to Wiring Repairs . Is the action complete? | -- | -- | |
19 | Replace the A/C refrigerant pressure sensor. Refer to A/C Refrigerant Pressure Sensor Replacement in Heater, Ventilation and Air Conditioning. Is the action complete? | -- | -- | |
|
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||
21 |
Is A/C High Side Pressure between the specified values? | 0.1 V-4.8 V | System OK |
