All thermostats include nut 25-0066. Thermostats are used to prevent icing of the coil by cycling the compressor clutch. Temp settings are 26 F (-3C) cut out and 35 F (2 C) cut in. Capillary tube to be inserted in the coldest area in the coil. It must be inserted with a minimum 15% of the capillary tubes total length.