Circuit Description
The powertrain control module (PCM) or engine control module (ECM) monitors the high side refrigerant pressure via an A/C refrigerant pressure sensor. The PCM/ECM supplies a 5-volt reference and a low reference to the sensor. Changes in the A/C refrigerant pressure cause the A/C refrigerant pressure sensor signal to the PCM/ECM to vary. When the pressure is high, the signal voltage is high. When the pressure is low, the signal voltage is low. When pressure is high, the PCM commands the cooling fans ON. When pressure is too high or too low, the PCM/ECM will not allow the A/C compressor clutch to engage.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0530 Air Conditioning (A/C) Refrigerant Pressure Sensor Signal Circuit Too Low or Too High
Conditions for Running the DTC
| • | The engine is running. |
| • | A/C has been requested. |
Conditions for Setting the DTC
| • | The PCM/ECM detects the signal circuit is less than 5 counts (0.09 volt) or more than 250 counts (4.9 volts). |
| • | The condition exists for 20 seconds. |
Action Taken When the DTC Sets
| • | The PCM/ECM will not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM/ECM stores the Failure Records. |
| • | The A/C compressor clutch is disabled. |
Conditions for Clearing the DTC
| • | The DTC will become history if the PCM/ECM no longer detects a failure. |
| • | The history DTC will clear after 40 fault-free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Diagnostic Aids
If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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If the pressure signal voltage stays high after disconnecting the pressure sensor electrical connector, the signal circuit is shorted to voltage, or the PCM/ECM is faulty.
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This step tests for a high resistance or for an open in the ground circuit.
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This vehicle is equipped with a PCM/ECM which utilizes an electrically erasable programmable read-only memory (EEPROM). Before you replace the PCM/ECM, program the new PCM/ECM.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Important: The ambient air temperature must be above 3°C (38°F).
Does the A/C compressor operate? | -- | Go to Step 3 | |
3 |
Does the scan tool indicate that the A/C High Side Pressure parameter is within the specified range? | 0.1-4.9 V | Go to Diagnostic Aids | Go to Step 4 |
Does the scan tool indicate that the A/C High Side Pressure parameter is less than the specified value? | 0.1 V | Go to Step 5 | Go to Step 11 | |
5 |
Does the scan tool indicate that the A/C High Side Pressure parameter is greater than the specified value? | 4.9 V | Go to Step 6 | Go to Step 9 |
6 |
Is the voltage measurement less than the specified value? | 5 V | Go to Step 7 | Go to Step 8 |
Is the resistance measurement near the specified value? | 5 ohms | Go to Step 13 | Go to Step 12 | |
8 | Test the 5-volt reference circuit of the A/C refrigerant pressure sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 |
9 | Test the 5-volt reference circuit of the A/C refrigerant pressure sensor for a short to ground, for a high resistance, or for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 10 |
10 | Test the signal circuit of the A/C refrigerant pressure sensor for a short to ground, for a high resistance, or for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 |
11 | Test the signal circuit of the A/C refrigerant pressure sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 |
12 |
Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 |
13 | Inspect for bad connections at the harness connector of the A/C refrigerant pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 |
14 | Inspect for bad connections at the harness connector of the PCM/ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 |
15 | Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | -- | Go to Step 17 | -- |
Replace the PCM/ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 17 | -- | |
17 |
Does the DTC set again? | -- | Go to Step 2 | System OK |
