TIAGO

HVAC

-0.029

10.1.5.6. TRINARY PRESSURE SWITCH / PRES-

SURE 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 pressure reaches 0.225

+0.025

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

below 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

system pressure drops below 2.25 MPa.

LOCATION:

PRESSURE SENSOR (PETROL VERSION)

LOCATION:

PRESSURE SWITCH (DIESEL VERSION)

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