Trinary Valve. This is actually a triple-switch based on the refrigerant pressure.

If the pressure on the system is normal then it allows operation of the AC compressor and left side fan. When the pressure on the system rises (due to high ambient temperature or when there is no proper air flow on the condensers eg. during traffic) it triggers the right side fan to help the system lower its pressure and increase the cooling effect.

In addition, it serves as a minimum/maximum pressure switch in the case of a malfunctioning subsystem of the A/C unit (compressor or condenser fan) and it is installed on the filter/dryer.