When operating the A/C switch

The air thermo sensor, which senses the temperature of the air flowing out of the evaporator, deactivates the compressor at 1°C (33.8°F) or below.
A/C controller assembly (A/C-ECU) detect refrigerant pressure by A/C pressure sensor and turns OFF when the refrigerant pressure becomes excessively high or low, thus protecting the compressor circuit (See Table below "A/C COMPRESSOR CLUTCH RELAY ON CONDITIONS" ).
When the air thermo sensor is activated, and the ignition switch, blower switch, and A/C switch are ON, the A/C compressor clutch relay is energized.