NEXON BSVI MCE - SERVICE MANUAL

HVAC 18 -0.029 +0.025 F. TRINARY PRESSURE SWITCH / PRESSURE SENSOR The pressure in the system is monitored by a Trinary pressure switch. The Trinary pressure switch triggers at 3 pressure values and sends request to Engine EMS ECU for compressor shut OFF or to increase radiator fan speed depending on system pressure. Trinary pressure switch is provided on the high pres- sure tube liquid line of the refrigerant and it is functionally connected to engine EMS to control the AC compressor and radiator/ condenser fan through the Engine EMS. It also gives a feedback to the Con- trol panel in case of its intervention. It has the following three functions: 1. Low Pressure Shut OFF: When the pressure drops below 0.196 ± 0.02 MPa, indicating a leakage, the compressor is shut OFF. It switches ON the compressor again after the system pres- sure reaches 0.225 2. Middle Pressure detection: When the system pressure reaches 2.01 ± 0.1 MPa it requests Engine EMS to run the radiator/ condenser fan at a higher speed. When the pressure drops be- low 1.52 ± 0.15 MPa the fan is requested to run at normal speed. 3. High pressure shut OFF: When the pressure rises above 3.14 ± 0.2 MPa, indicating a pres- sure build up, the compressor is shut OFF. It switches ON the compressor again after the sys- tem pressure drops below 2.25 MPa. LOCATION: PRESSURE SENSOR (PETROL) PIN OUT: LOCATION: PRESSURE SWITCH (DIESEL) The pressure switch is located on the high pressure refrigerant liquid tube, beside the brake booster. PIN OUT: PIN NO DESCRIPTION 1 -2 Middle pressure 3-4 Low and High Pressure