System Description

MAGNET CLUTCH CONTROL SYSTEM


System Description

Unified meter and A/C amp. controls compressor operation by ambient temperature, intake air temperature and signal from ECM.

SYSTEM OPERATION
When A/C switch, AUTO switch, DEF switch is pressed, unified meter and A/C 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 unified meter and A/C amp. via CAN communication line.
ECM sends A/C compressor feedback signal to unified meter and A/C amp., then, uses input A/C compressor feedback signal to control air inlet.

Compressor Protection Control
ECM makes the A/C relay go OFF and stops the compressor when pressure on the high-pressure side detected by refrigerant pressure sensor is over approximately 3,119 kPa (31.19 bar, 31.8 kg/cm2, 452 psi), or below approximately 118 kPa (1.18 bar, 1.2 kg/cm2, 17 psi).

Low Temperature Protection Control
It turns the A/C relay OFF and stops the compressor by the signal from unified meter and A/C 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.