The cultus one is a thermoswitch which opens up at 108c, meaning once 108c is reached at the sensor, the circuit opens up, cutting off whatever is connected, in your case its the compressor relay.
You can also do it the old vw/audi or bmw/merc way (ancient ones) - where this certain switch intercepted the compressor control wire directly, in vw/audi they had a 2 wire magnet, the switch controlled the magnet field coil ground leg.