GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The 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 too high the powertrain control module (PCM) will not allow the A/C compressor clutch to engage.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0530 Air Conditioning Refrigerant Pressure Sensor Circuit

Conditions for Running the DTC

The ECM detects an A/C request.

Conditions for Setting the DTC

    • The A/C refrigerant pressure sensor signal is less than 0.1 volts for 5 seconds.
    • The A/C refrigerant pressure sensor signal is greater than 4.9 volts for 5 seconds.

Action Taken When the DTC Sets

The malfunction indicator lamp (MIL) will not illuminate.

Conditions for Clearing the DTC

    • The DTC will become history if the 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

For an intermittent, refer to Testing for Intermittent Conditions and Poor Connections.

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step tests the ability of the A/C refrigerant pressure sensor to create a voltage signal for the ECM to monitor the A/C refrigerant pressure. Measure the voltage at the A/C refrigerant pressure sensor, if the voltage is measured at the connector for the sensor, misdiagnosis will occur.

Step

Action

Value(s)

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

2

Does the scan tool indicate that DTC P0530 is current?

--

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn OFF the ignition.
  2. Disconnect the A/C refrigerant pressure sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 5-volt reference circuit to the low reference circuit of the A/C refrigerant pressure sensor.

Does the voltage measure near the specified value?

5 V

Go to Step 5

Go to Step 4

4

Measure the voltage from the 5-volt reference circuit of the A/C refrigerant pressure sensor to a good ground.

Does the voltage measure near the specified value?

5 V

Go to Step 7

Go to Step 6

5

  1. With the A/C refrigerant pressure sensor disconnected, connect a jumper wire between the A/C refrigerant pressure sensor and the electrical connector of the A/C refrigerant pressure sensor for the following circuits:
  2. • The 5-volt reference circuit
    • The low reference circuit
  3. Measure the voltage at the A/C refrigerant pressure sensor terminal for the A/C refrigerant pressure sensor signal.

Does the voltage measure less than the specified value?

1.5 V

Go to Step 8

Go to Step 9

6

Test the 5-volt reference circuit of the A/C refrigerant pressure sensor for the following:

    • A short to ground
    • A short to voltage
    •  A high resistance
    • An open

Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

7

Test the low reference circuit of the A/C refrigerant pressure sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

8

Test the signal circuit of the A/C refrigerant pressure sensor for the following:

    • A short to ground
    • A short to voltage
    •  A high resistance
    • An open

Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

9

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.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

10

Inspect for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

11

Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement.

Did you complete the replacement?

--

Go to Step 13

--

12

Replace the ECM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 13

--

13

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

Does the DTC reset?

--

Go to Step 2

System OK