GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2005 🢒 Aztek - AWD 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 DTC P0530

Circuit Description

The powertrain control module (PCM) or engine control module (ECM) monitors the high side refrigerant pressure via a A/C refrigerant pressure sensor. 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/ECM 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.

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 (4.90 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:

  1. 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.

    2.

  2. Tests for a high resistance or for an open in the ground circuit.

    3.

  3. 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).

  1. Turn OFF the ignition.
  2. Inspect the A/C compressor for free rotation operation.
  3. Start the engine.
  4. Place the HVAC control module in the OFF position.

Does the A/C compressor operate?

--

Go to HVAC Compressor Clutch Does Not Disengage

Go to Step 3

3
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the A/C High Side Pressure parameter in the powertrain control module (PCM) or engine control module (ECM) Engine Data-2 list.

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

4

  1. Turn OFF the ignition.
  2. Disconnect the A/C refrigerant pressure sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the A/C High Side Pressure parameter.

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
  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper wire between the 5-volt reference circuit and the signal circuit of the A/C refrigerant pressure sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the A/C High Side Pressure parameter.

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
  1. Disconnect the fused jumper wire.
  2. Measure the voltage between the 5-volt reference circuit of the A/C refrigerant pressure sensor and the ground circuit of the A/C refrigerant pressure sensor.

Is the voltage measurement less than the specified value?

5.0 V

Go to Step 7

Go to Step 8

7

  1. Turn OFF the ignition.
  2. Measure the resistance from the low reference circuit of the A/C refrigerant pressure sensor to a good ground.

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 the following:

    • A short to ground
    • A high resistance
    • 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 the following:

    • A short to ground
    • A high resistance
    • 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
  1. Disconnect the PCM/ECM.
  2. Test the low reference circuit of the A/C refrigerant pressure sensor for high resistance or for an open. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

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

--

16

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
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running, as specified in the supporting text.

Does the DTC set again?

--

Go to Step 2

System OK