The ECM(Engine Control Module) monitors the A/C Refrigerant Pressure Sensor. The A/C Pressure Sensor is placed in the high pressure line. This signal indicates how much load the A/C compressor is putting on the engine and is one of the factors used by the ECM in order to determine the idle air control position for the idle speed. The signal is a voltage which is proportional to the A/C pressure from 0 to 5V. Low pressure produces a low voltage signal and high pressure a high-voltage signal.
Checking output signals from A/C pressure sensor under detecting condition, if an signal below 0.25V lasts for more than 10 sec., ECM sets P0532.
Item | Detecting Condition | Possible cause |
DTC Strategy |
•
Detects sensor signal short to low voltage |
•
Poor connection
•
Open in power circuit
•
Open or short to ground in signal circuit
•
Faulty A/C pressure sensor
•
Faulty ECM |
Enable Conditions |
•
Engine works | |
Threshold value |
•
Sensor output voltage < 0.25V | |
Diagnosis Time |
•
Continuous (More than 10 seconds failure for every 20 seconds test ) | |
MIL On Condition |
•
DTC only (NO MIL ON) |
Pressure(psi) | 101.4 | 390.9 | 1723.7 | 3031.6 | 3206.1 |
Voltage(V) | 0.5 | 0.87 | 2.57 | 4.24 | 4.46 |
Fig.1) Normal waveforms of A/C pressure sensor during the time from turning on A/C switch to turning off A/C switch
Fig.2) Normal data of A/C pressure sensor without A/C switch ON.
Fig.3) Abnormal data of A/C pressure sensor when A/C pressure sensor circuit open.
