Code P1530, A/C Pressure Sensor: Notes

A/C refrigerant pressure sensor responds to changes in A/C refrigerant system high side pressure. 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.

Signal is a voltage which is proportional to pressure. Sensor's range of operation is zero to 454 psi. At zero psi, signal will be approximately .1 volt, varying up to approximately 4.9 volts at 454 psi or above. Code P1530 will set if voltage is greater than 4.9 volts (454 psi) or less than .3 volt (7.5 psi) for 5 or more seconds. A/C compressor clutch is disabled by PCM if fault is present.

1. This step checks voltage signal being received by PCM from A/C refrigerant pressure sensor.
2. Checks if high voltage signal is from a shorted sensor or a short to voltage in circuit. Normally, disconnecting sensor would make a normal circuit go to near zero volt.
3. Checks if low voltage signal is from sensor or circuit. Jumpering sensor circuits together checks circuit, connections and PCM.
4. This step checks if low voltage signal was due to an open in sensor circuit or 5 volts reference circuit since previous step eliminated pressure sensor.
5. 5 volts reference for Throttle Position (TP) sensor connects to same 5 volt power supply in PCM. If 5 volts reference circuit to TP sensor has a short to ground, MAP sensor and A/C refrigerant pressure sensor 5 volts reference circuit will also have a short to ground because they connect to same power supply in PCM. A short to ground on either 5 volts reference circuit does not damage PCM 5 volts power supply. When short is repaired, PCM 5 volts supply will return to normal.