I would have to look up that particular vehicle, but in general a trinary switch performs 3 functions.
1) shuts off the compressor if the refrigerant charge (pressure) is excessively low.
2) shuts off the compressor if the system pressure is too high
3) turns on the cooling fans when the system high pressure reaches a certain level.
How many wires are in the connector for the switch?
I have been retired for some years, so don't have a lot of the manuals on the newer vehicles at home.
Here is a like to the wireing diagram.
All Wiring Diagrams for Toyota Camry CE 1999 – Wiring diagrams for cars
