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 A/C refrigerant pressure sensor operates much like other 3-wire sensors. The PCM supplies a 5.0 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 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. When the pressures are out of range (high or low) for a predetermined time, the PCM disables the A/C compressor clutch and set a DTC P0530. When a DTC P0530 sets, the PCM disables the A/C compressor clutch so compressor damage does not occur.
Conditions for Setting the DTC
| • | The PCM detects an A/C request. |
| • | A/C refrigerant pressure sensor indicates A/C refrigerant pressure is below -8.0 psi for 5.0 seconds. |
| • | A/C refrigerant pressure sensor indicates A/C refrigerant pressure is above 448 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
If the test did not fail this ignition cycle, move the related electrical harnesses and the connectors while monitoring a scan tool.
For an intermittent, refer to Symptoms
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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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 data in order to determine when the DTC P0530 set.
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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.
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This step checks for a good ground circuit.
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This step checks the integrity of the A/C refrigerant pressure sensor signal circuit.
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If you have thoroughly checked the 5.0 volt reference circuit (for opens, shorts to ground, PCM connections etc.) and checks OK, then replace the PCM.
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Important: Inspect the PCM engine grounds for being secure and clean.
If you have thoroughly checked 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 P1635 Fail This Ignition cycle? | -- | ||
Does the scan tool indicate the A/C High Side between the specified range? | 0.1-1.8V | |||
4 |
Did the test Fail This Ignition cycle while operating the vehicle in the conditions that you observed? | -- | Refer 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? | 1.0V | |||
6 | Measure the voltage from the A/C refrigerant pressure sensor 5.0 volt reference circuit to the battery ground using the DMM J 39200 . Is the voltage near the specified value? | 5.0V | ||
Measure the voltage from the A/C refrigerant pressure sensor 5.0 volt reference circuit to the sensor ground circuit using the DMM J 39200 . Is the voltage at the specified value? | 5.0V | |||
Jumper the 5.0 volt reference circuit to the A/C refrigerant pressure sensor signal circuit using a fused jumper wire. Does the scan tool indicate the A/C High Side voltage at the specified value? | 5.0V | |||
9 | Repair the A/C refrigerant pressure sensor connection or sensor. Is the action complete? | -- | -- | |
10 | Repair the short to voltage in the A/C refrigerant pressure sensor signal circuit. Is the action complete? | -- | -- | |
Repair the 5.0 volt reference circuit to the A/C refrigerant pressure sensor. Is the action complete? | -- | -- | ||
Repair the ground circuit to the A/C refrigerant pressure sensor. Is the action complete? | -- | -- | ||
13 | Repair the signal circuit to the A/C refrigerant pressure sensor. 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 |
