When troubleshooting a refrigeration system, sometimes it helps to go back to the basics. Remembering that HVAC systems are dynamic devices with multiple components that all work together can help identify some common defects. Some problems may change one operating condition — for example, suction pressure — in a similar way, but usually another condition, such as evaporator superheat heat, will be different. Looking at multiple operating conditions during the troubleshooting process allows a tech to determine the true problem.
Too often, we try to troubleshoot a system by looking only at one operating condition. We then guess at the problem, sometimes we guess right, and sometimes we guess wrong. In any case, it is a guess, which is not a great method of troubleshooting. There are many times where a problem in one area can be caused by several different issues.