Cannot find a themo senser on the aircon cooler?

I serviced my a/c changed the filter and re gased the system, but the compressure dosen't switch of once the cabin temperature drops down to 7 c*.
On every a/c system once the temp drops to the set level the compressure clutch releases and switches back on when the temp starts to rise in the cabin,

I serched high and low for a temperature senser on the a/c system but coulden't find one,

Can any body tell me where is the senser located and where is the controll box located ( A/C controll box )

Thank you.