This instructional package, one in a series of individualized instructional units on automobile air conditioning, consists of a student guide and an instructor guide dealing with the principles of refrigeration. Covered in the module are defining the term heat, defining the term British Thermal Unit (BTU), defining the term latent heat, listing the three methods of transferring heat, describing the effect of pressure on vaporization and evaporation of the refrigerant, and describing what happens in the air conditioning system as the refrigerant makes a complete circuit. The student guide contains an introduction, a list of procedures for completing the unit, and an information sheet. Included in the instructor guide are an introduction, performance objectives, a list of references, suggested activities, a student posttest, answers to the posttest, and instructional script. (MN)