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 refrigerant pressure. The PCM uses this information to turn ON the engine coolant fans when the A/C refrigerant pressure is high and to disengage the A/C relay when the 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 ground to the sensor. The A/C pressure sensor varies the 5 volt reference relative to changes in the A/C refrigerant pressure. The PCM monitors the A/C refrigerant pressure signal to determine when the A/C pressure is outside the calibrated range of the sensor. When the signal is out of range (high or low) for a prolonged period of time, the PCM sets DTC P0530. When DTC P0530 sets, the PCM disengages the A/C relay to disable the A/C compressor clutch. This is done to protect the A/C 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 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 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. |
| • | DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed. |
Diagnostic Aids
Check for the following conditions:
Important: Be sure to inspect PCM engine grounds for being secure and clean.
| • | Poor connection at PCM and A/C Refrigerant Sensor. |
| Inspect harness connectors for 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 malfunction. |
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
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 Records data to determine the conditions that were present when DTC P0530 set.
-
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 being replaced, the new PCM must be programmed.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Was 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 (high side) pressure sensor voltage. Is the voltage less than the specified value? | 0.1V | |||||||||
3 | Is the A/C refrigerant (high side) pressure sensor voltage greater than the specified value? | 4.2V | Go to Diagnostic Aids | |||||||
With a scan tool, observe the A/C refrigerant pressure sensor voltage while you disconnect the A/C refrigerant pressure sensor. Is the voltage at or near the specified value? | 0V | |||||||||
5 |
Is the voltage at or near the specified value? | 5V | ||||||||
6 | Measure the voltage between the 5 volt reference B circuit and the ground circuit at the A/C refrigerant pressure sensor harness connector using a J 39200 Digital Multimeter. Is voltage at or near the specified value? | 5V | ||||||||
7 | Check for a poor 5 volt reference B circuit connection at the PCM. Refer to Intermittents and Poor Connections Diagnosis . Was a problem found? | -- | ||||||||
8 | Check for the following conditions:
Was a problem found? | -- | ||||||||
9 | Check the A/C refrigerant pressure signal circuit for a poor connection at the PCM. 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. Was a problem found? | -- | ||||||||
11 | Check the A/C refrigerant pressure signal circuit between the A/C pressure sensor connector and the PCM for a short to voltage. Was a problem found? | -- | ||||||||
12 | Check for a short to voltage on the 5 volt reference B circuit. Was a problem found? | -- | ||||||||
13 | Check for a poor sensor ground circuit connection at the PCM. Was a problem found? | -- | ||||||||
14 | Check for a poor sensor ground circuit connection at the A/C refrigerant pressure sensor connector. Was a problem found? | -- | ||||||||
15 | Check for an open or a faulty splice in the sensor ground circuit. Was a problem found? | -- | ||||||||
16 | Check for a poor 5 volt reference B circuit or A/C refrigerant pressure signal circuit connection at the A/C refrigerant pressure sensor. Was a problem found? | -- | ||||||||
17 | Repair faulty connection. Refer to Connector Repairs . 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 HVAC. Is the action complete? | -- | -- | |||||||
|
Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | -- | ||||||||
21 |
Is the voltage between the specified values? | 0.1-4.8V | System OK |
