DTC P1599: A/C Pressure Sensor Volts Too Low: Description
A/C pressure sensor signal voltage is monitored with engine running and A/C relay energized. DTC will set in Powertrain Control Module (PCM) memory when PCM senses A/C pressure sensor voltage is less than .5 volt. Possible causes for DTC to set are: defective A/C pressure sensor, defective PCM, defective connectors or defective wiring.