DTC 70

Trouble Code 70 Chart:

A/C Refrigerant Pressure Sensor Circuit (High Pressure):

CIRCUIT DESCRIPTION
The A/C Refrigerant Pressure Sensor is located in the high side of the A/C cooling system and signals the Powertrain Control Module (PCM) of refrigerant pressure-changes. This input indicates how much load the A/C compressor is putting on the engine. The PCM uses this input to determine Idle Air Control (IAC) valve position for idle speed control. This 3 wire sensor has a 5 volt reference input, a signal line and a ground.

When pressure is low, a low signal voltage is sensed at the PCM. As pressure rises, the voltage increases at PCM terminal "A5" which is translated by the PCM into rising pressure. If the signal voltage remains above a calibrated value, a DTC 70 is set which indicates a sensor or circuit failure.

DIAGNOSTIC TROUBLE CODE (DTC) 70 WILL SET WHEN
The signal voltage sensed at terminal "A5" 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 Malfunction Indicator Lamp (MIL) will not become illuminated, the A/C compressor will be disabled and the engine cooling fans will be enabled.

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.


DTC CHART 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 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.