Code 70, High A/C Pressure: Notes

A/C pressure sensor responds to changes in A/C refrigerant system high side pressure. PCM uses A/C compressor load input to determine engine idle speed. Sensor uses a 5-volt reference signal from PCM and returns an input signal to PCM on a separate line. Low pressure (zero psi) will return a signal of about .1 volt. High pressure will return a signal of about 4.9 volts. PCM will disable A/C if Code 66 is present.

1. This step checks the voltage signal being received by the PCM from the A/C refrigerant pressure sensor.
2. Checks to see if the high voltage signal is from a shorted sensor or a short to voltage in the circuit. Normally, disconnecting the sensor would make a normal circuit go to near zero volts.