Code P1530, A/C Refrigerant Pressure: Notes

A/C refrigerant pressure sensor is located in the high side of A/C cooling system and signals PCM of refrigerant pressure changes. This input indicates how much load A/C compressor is putting on engine. PCM uses this input to determine IAC valve position for idle speed control. This 3 wire sensor has a 5 volts reference input, a signal line and a ground.

When pressure is low, a low signal is sensed at PCM. As pressure rises, voltage increases at PCM which is translated by PCM into a rising pressure. Code P1530 will set if signal voltage remains below a calibrated value, indicating a sensor or circuit failure.

Code P1530 will set when the following conditions are present.

• Signal voltage sensed at PCM is less than .1 volt for 25.4 seconds when A/C is selected on and engine is running, or signal voltage sensed at PCM is greater than 4.92 volts for 25.4 seconds when A/C is selected on and engine is running. Code P1530 does not illuminate the Malfunction Indicator Light (MIL) and A/C compressor will be disabled.
  NOTE: Test numbers refer to numbers on diagnostic chart.

1. This step checks voltage signal being received by PCM from A/C pressure sensor.
2. Checks if low voltage signal is from sensor or circuit. Jumpering sensor circuit to 5 volts checks circuit, connections and PCM.
3. This step checks if low signal voltage was due to an open in sensor circuit or 5 volts reference circuit since previous step eliminated pressure sensor.
4. Checks if high voltage signal is from a shorted sensor or a short to voltage in circuit, or ground open. Normally, disconnecting sensor would make a normal circuit go to near zero volt.