SYSTEM OPERATION

- When A/C switch, AUTO switch, DEF switch is pressed or when shifting mode position D/F, A/C auto amp. transmits A/C switch signal and blower fan motor switch signal to ECM, via CAN communication.
- ECM judges whether compressor can be turned ON, based on each sensor status (refrigerant-pressure sensor signal, throttle angle, etc.). If it judges compressor can be turned ON, it sends A/C compressor request signal to IPDM E/R, via CAN communication.
- Upon receipt of A/C compressor request signal from ECM, IPDM E/R turns A/C relay ON to operate compressor.
- When sending A/C compressor request signal to IPDM E/R via CAN communication line, ECM simultaneously sends A/C compressor feedback signal to A/C auto amp. via CAN communication line.
- ECM sends A/C compressor feedback signal to A/C auto amp., then, uses input A/C compressor feedback signal to control air inlet.

COMPRESSOR PROTECTION CONTROL
Compressor Protection Control at Pressure Malfunction
The high-pressure side pressure detected by the refrigerant pressure sensor is approximately 3,120 kPa (31.8 kg/cm2, 452 psi) or more when the engine speed is less than 1,500 rpm. It is approximately 2,740 kPa (27.9 kg/cm2, 397 psi) when the engine speed is 1,500 rpm or more. When it is approximately 120 kPa (1.2 kg/cm2, 17 psi) or less, ECM turns the A/C relay to OFF and stops the compressor.
Compressor Oil Circulation Control
When the engine coolant temperature is approximately 56°C (133°F) or less, it turns the compressor to ON at the engine start for approximately 6 seconds and circulates the compressor oil.
Low Temperature Protection Control
It turns the A/C relay OFF and stops the compressor by the signal from A/C auto amp. according to the evaporator passing air temperature detected by the intake sensor.
It turns the compressor to OFF when the evaporator passing air temperature becomes −5°C (23°F) or less. In addition, it turns the compressor to ON when the evaporator passing air temperature becomes 1°C (34°F) or more.
Operating Rate Control
It controls the operating rate of the compressor by the ambient temperature when the set temperature is set to any condition other than the full cold or when the air outlet is “VENT”, “B/L”, or “FOOT”.
Air Conditioner Cut Control
ECM turns the A/C relay to OFF and stops the compressor at engine high load. Refer to System Diagram (GT-R certified NISSAN dealer).
Fail-safe Control
When a communication malfunction between A/C auto amp. and AV control unit and preset switch is continuing for approximately 30 seconds or more, the A/C auto amp. automatically controls air outlet and fan speed, fixes the air inlet to fresh air intake, maintains the set temperature data before the communication malfunction occurred, and turns the compressor to ON. Turn the compressor to ON with the following conditions if the condition before the communication error occurs was A/C switch OFF.