A Binary or Trinary switch can be installed anywhere in the High side liquid line, before or after the drier or in the drier itself.

If the A/C is turned on and the pressure switch senses the High side pressure is below 30 psi, it will prevent the compressor clutch from engaging and causing catastrophic failure.

If the opposite happens and the high side pressure gets too high, it will turn the compressor off, hopefully before the compressor locks up or blows a hose off.