Systematic troubleshooting requires discipline in mastering the functions of all the refrigeration system's components. However, being able to recognize what pressure, state, and condition the working fluid (refrigerant) is in throughout the system's components is essential.
Figure 1 illustrates the basic refrigeration system. The circled numbers in the diagram refer to 10 locations within a system that are the focus of this article. An explanation of each of those point's pressure, condition, and state should clarify any system weaknesses. Here are some assumptions: The refrigerant is R-134a; the discharge (condensing) pressure is 124 psig (100 degrees F); the suction (evaporating) pressure is 6 psig (0 degrees); the discharge temperature is 180 degrees; the condenser outlet temperature is 90 degrees; the thermostatic expansion valve (TXV) inlet temperature is 80 degrees; the evaporator outlet temperature is 10 degrees; and the compressor inlet temperature is 40 degrees.