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 A/C refrigerant pressure sensor operates like other 3-wire sensors. 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
| • | Engine is running. |
| • | A/C is requested. |
Conditions for Setting the DTC
| • | A/C refrigerant pressure sensor signal voltage is below 0.1 Volts. |
| • | A/C refrigerant pressure sensor signal voltage is above 4.94 Volts. |
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 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 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, 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 to the step numbers on the diagnostic table.
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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.
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This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read only memory (EPROM). When the PCM is being replaced, the new PCM must be programmed.
Step 5 | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board (OBD) Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Does the scan tool indicate that the A/C Pressure Sensor parameter is within the specified range? | 0.1 V to 4.9 V | Go to Diagnostic Aids | Go to Step 3 |
Does the scan tool indicate that the A/C pressure sensor parameter is less than the specified value? | 0.1 V | Go to Step 4 | Go to Step 9 | |
4 |
Does the scan tool indicate that the A/C pressure sensor parameter is more than the specified value? | 4.9 V | Go to Step 5 | Go to Step 7 |
5 |
Does the voltage measure less than the specified value? | 5.1 V | Go to Step 10 | Go to Step 6 |
6 | Test the 5 volt reference B circuit of the A/C pressure sensor for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
7 | Test the 5 volt reference B circuit of the A/C pressure sensor for a short to ground, high resistance, or an open. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 8 |
8 | Test the signal circuit of the A/C pressure sensor for a short to ground, high resistance, or an open. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
9 | Test the signal circuit of the A /C pressure sensor for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
10 |
Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 11 |
11 | Inspect for poor connections at the harness connector of the A/C pressure sensor. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 |
12 | Inspect for poor connections at the harness connector of the PCM. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 |
13 | Replace the A/C pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement in HVAC. Did you complete the replacement? | -- | Go to Step 15 | -- |
|
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming Did you complete the replacement? | -- | Go to Step 15 | -- | |
15 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
