Manufacturers of refrigerants, controls, and other suppliers distribute hundreds of thousands of pressure-temperature charts to the trade every year. It would be rare indeed to find a service technician who could not put their hands on a pressure-temperature card at a minute�s notice.
In spite of the widespread availability and apparent reference to the pressure-temperature relationship,
very few service technicians use the P-T chart properly in diagnosing service problems.
The purpose of this article is to not only demonstrate the proper use of the pressure-temperature relationship, but to also illustrate how it can be used to thoroughly analyze a refrigeration or air