Refer to
A/C System
for complete circuit details.
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 PCM utilizes this information in order to turn ON the engine coolant fans when the A/C refrigerant pressure is high.
The PCM supplies a 5.0 volt reference and ground to the sensor. As the A/C pressure increases or decreases, the resistance of the sensor changes and varies the amount of signal returning to the PCM.
The PCM monitors the A/C refrigerant pressure 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 (high or low) for a predetermined time. The PCM disables the A/C compressor in order to prevent A/C compressor damage.
Conditions for Running the DTC
The PCM detects an A/C request.
Conditions for Setting the DTC
A/C refrigerant pressure sensor indicates A/C refrigerant pressure is below 3.0 psi for 5.0 seconds.
OR
A/C refrigerant pressure sensor indicates A/C refrigerant pressure is above 445 psi for 5.0 seconds.
Action Taken When the DTC Sets
| • | The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records. |
Conditions for Clearing the DTC
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Use a scan tool in order to clear the DTC. |
Diagnostic Aids
Important:
• Remove any debris from the PCM connector surfaces before servicing
the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM.
Ensure that the gaskets are installed correctly. The gaskets prevent water
intrusion into the PCM. • For any test that requires probing the PCM or a component
harness connector, use the Connector Test Adapter Kit J 35616
. Using this kit prevents damage
to the harness/component terminals. Refer to
Using Connector Test Adapters
in Wiring Systems.
| • | If the test did not fail this ignition cycle, move the related electrical harnesses and the connectors while monitoring a scan tool. |
| • | Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. |
| • | For an intermittent, refer to Symptoms . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
The normal A/C voltage is between 1.0 and 1.8 volts. If the A/C voltage is within the range, review the Freeze Frame/Failure Records data in order to determine when the DTC P0530 set.
-
If the A/C pressure/voltage stays high after disconnecting the A/C refrigerant pressure sensor electrical connector, this indicates the signal circuit is shorted to a voltage.
-
This step tests for a good ground circuit.
-
This step tests the integrity of the A/C refrigerant pressure sensor signal circuit.
-
If you have thoroughly tested the 5 volt reference circuit (for opens, shorts to ground, PCM connections etc.) and tests OK, then replace the PCM.
-
If you have thoroughly tested the ground circuit for opens and the PCM connections are OK, then replace the PCM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Did DTC P1639 Fail This Ignition cycle? | -- | ||
Does the scan tool indicate the A/C High Side between the specified range? | 0.1-1.8V | |||
4 |
Does the scan tool indicate that this diagnostic failed this ignition? | -- | Go to Diagnostic Aids | |
Disconnect the A/C refrigerant pressure sensor electrical connector. Does the scan tool indicate the A/C High Side less than the specified value? | 1V | |||
6 | Measure the voltage from the A/C refrigerant pressure sensor 5 volt reference circuit to the battery ground using the DMM J 39200 . Is the voltage near the specified value? | 5V | ||
Measure the voltage from the A/C refrigerant pressure sensor 5 volt reference circuit to the sensor ground circuit using the DMM J 39200 . Is the voltage at the specified value? | 5V | |||
Jumper the 5 volt reference circuit to the A/C refrigerant pressure sensor signal circuit using a fused jumper wire. Refer to Using Fused Jumper Wires in Wiring Systems. Does the scan tool indicate the A/C High Side voltage at the specified value? | 5V | |||
9 | Repair the faulty A/C refrigerant pressure sensor connection or faulty sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement in HVAC system Manual. Is the action complete? | -- | -- | |
10 | Repair the short to voltage in the A/C refrigerant pressure sensor signal circuit. Refer to Wiring Repairs in Wiring Systems for procedures. Is the action complete? | -- | -- | |
|
Important: Inspect the PCM engine grounds for being secure and clean. Repair the 5 volt reference circuit to the A/C refrigerant pressure sensor. Refer to Wiring Repairs in Wiring Systems for procedures. Is the action complete? | -- | -- | ||
Repair the ground circuit to the A/C refrigerant pressure sensor. Refer to Wiring Repairs in Wiring Systems for procedures. Is the action complete? | -- | -- | ||
13 | Repair the signal circuit to the A/C refrigerant pressure sensor. Refer to Wiring Repairs in Wiring Systems for procedures. Is the action complete? | -- | -- | |
14 |
Does the scan tool indicate that this test ran and passed? | -- | ||
15 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
