DTC 70

DTC 70 Chart:

A/C Circuit:

Circuit Description:
The A/C refrigerant pressure sensor responds to changes in A/C refrigerant system high side pressure. This input indicates how much load the A/C compressor is putting on the engine and is one of the factors used by the PCM to determine IAC valve position for idle speed control. The circuit consists of a 5 volt reference and a ground, both provided by the PCM, and a signal line to the PCM. The signal is a voltage which is proportional to the pressure. The sensor's range of operation is 0 to 450 psi. At 0 psi, the signal will be about .1 volt, varying up to about 4.9 volts at 450 psi or above.

DTC 70 Will Set When:
The signal voltage sensed at terminal "AS" is above 4.9 volts for 5 seconds when A/C is selected and the engine is running.

Action Taken (PCM will default to):
The MIL will not become illuminated, the A/C compressor will be disabled, the engine cooling fan will not be enabled unless A/C had been requested first and the vehicle speed is above 35 mph with a current DTC 70.

DTC 70 Will Clear When:
A current DTC 70 will clear when the refrigerant pressure sensor signal falls below the calibrated high pressure threshold. A history DTC 70 will clear after 50 consecutive ignition key cycles without a current DTC 70 being stored.

Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

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.

Diagnostic Aids:
DTC 70 sets when signal voltage falls outside the normal possible range of the sensor and is not due to a refrigerant system problem. If problem is intermittent, check for opens or shorts in harness or poor connections.