The powertrain control module (PCM) 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 commands the cooling fans on. When pressure is too high or too low the PCM will not allow the A/C compressor clutch to engage.
• | The engine is running. |
• | A/C has been requested. |
• | The PCM 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. |
• | The PCM will not illuminate the Malfunction Indicator Lamp (MIL). |
• | The PCM stores the failure records. |
• | The A/C compressor clutch is disabled. |
• | 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. |
The numbers below refer to the step numbers on the diagnostic table.
Tests for the proper operation of the circuit in the high voltage range.
Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.
Tests for a short to ground in the 5-volt reference circuit.
Step | Action | Values | Yes | No |
---|---|---|---|---|
Schematic Reference: HVAC Schematics | ||||
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Important: The ambient air temperature must be above 3 degrees Celsius (38 degrees Fahrenheit).
Does the A/C compressor operate? | -- | Go to Step 3 | |
3 |
Does the scan tool indicate that the A/C High Side Pressure parameter is within the specified range? | 0.09-4.90 V | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 4 |
Does the scan tool indicate that the A/C High Side Pressure parameter is less than the specified value? | 0.09 V | Go to Step 5 | Go to Step 11 | |
Does the scan tool indicate that the A/C High Side Pressure parameter is greater than the specified value? | 4.90 V | Go to Step 6 | Go to Step 9 | |
Does the voltage measure less than the specified value? | 5.1 V | Go to Step 7 | Go to Step 8 | |
7 |
Does the resistance measure less than 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 a short to ground, a high resistance, or 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 a short to ground, a high resistance or 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 | 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 in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 |
13 | 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 17 | Go to Step 15 |
14 | Inspect for poor connections at the harness connector of the powertrain control module. 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 |
Important: Perform the programming procedure for the powertrain control module. Replace the powertrain control module. Refer to Powertrain Control Module Replacement in Engine Controls. Did you complete the replacement? | -- | Go to Step 17 | -- |
17 |
Does the DTC reset? | -- | Go to Step 3 | System OK |