Circuit Description
The A/C system uses an A/C refrigerant pressure sensor mounted in the high side of the A/C system to monitor A/C refrigerant pressure. The powertrain control module (PCM) uses this information to turn ON the engine coolant fan high speed relay when the A/C refrigerant pressure is high.
The PCM supplies a 5-volt reference to the sensor. The sensor supplies a signal circuit to the PCM. As the A/C pressure increases or decreases, the resistance of the sensor changes and varies the signal voltage to the PCM. When the pressure is high the signal voltage is high. When the pressure is low the signal voltage is low.
The PCM monitors the sensor signal circuit and can determine when the A/C pressure is too high or too low. The PCM disables the A/C compressor clutch and sets a DTC P0530 when the pressures are out of range for a predetermined time.
Conditions for Running the DTC
| • | The engine is running. |
| • | A/C has been requested. |
Conditions for Setting the DTC
| • | The PCM detects the signal circuit is less than 0.02 volts or more than 4.9 volts. |
| • | The condition exists for 5 seconds. |
Action Taken When the DTC Sets
| • | The PCM will not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM records the operating conditions at the time the diagnostic fails. |
| • | The PCM stores this information in the Failure Records. |
| • | The multifunction display (MFD) in the instrument cluster will display a message at key-on and key-off. |
| • | The A/C compressor clutch is disabled. |
Conditions for Clearing the DTC
| • | The DTC will become history if the PCM 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
| • | DTC P0530 will only set with a short to voltage or an open circuit. A short to ground will not set the DTC, but the A/C system will be inoperative. |
| • | DTC P0530 sets when the signal voltage falls outside the normal possible range of the sensor. Repair any A/C pressure problems before using this table. |
| • | Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly check for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness. |
| • | If 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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Jumping the sensor signal circuit to ground checks if the signal circuit is OK. If the signal circuit is OK the voltage displayed on the scan tool will be less than 0.2 volts.
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Jumping the sensor signal circuit to the sensor ground circuit checks if the signal ground circuit is OK. If the signal ground circuit is OK the voltage displayed on the scan tool will be less than 0.2 volts.
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This test step checks the 5-volt reference circuit. An open in a shared 5-volt reference circuit can cause other DTC's to be set. If no other DTC's were set, the circuit must have an open between the sensor and the circuits wiring harness splice.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views | ||||
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Is the A/C high side pressure parameter greater than the specified value? | 4.0 V | Go to Step 8 | Go to Step 3 |
3 | Is the A/C high side pressure parameter less than the specified value? | 0.02 V | Go to Step 9 | Go to Step 4 |
Is the A/C high side pressure parameter less than the specified value? | 0.02 V | Go to Step 5 | Go to Step 9 | |
Is the A/C high side pressure parameter less than the specified value? | 0.02 V | Go to Step 6 | Go to Step 10 | |
With the A/C refrigerant pressure sensor still disconnected, measure the voltage at the harness connector of the 5-volt reference circuit of the A/C refrigerant pressure sensor. Refer to Measuring Voltage in Wiring Systems. Is the voltage at the specified value? | 5.0 V | Go to Step 7 | Go to Step 11 | |
7 |
Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 12 |
8 | 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 16 | Go to Step 13 |
9 | Test the signal circuit of the A/C refrigerant pressure sensor for an open, a short to ground, or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 |
10 | Test the low reference circuit of the A/C refrigerant pressure sensor for an open, a short to ground, or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 |
11 | Test the 5-volt reference circuit of the A/C refrigerant pressure sensor for an open, a high resistance, a short to ground, or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 |
12 | Inspect for poor 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 16 | Go to Step 14 |
13 | Inspect for poor connections at the harness connector of the PCM. 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 16 | Go to Step 15 |
14 | 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 16 | -- |
15 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls. Did you complete the replacement? | -- | Go to Step 16 | -- |
16 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
