While troubleshooting or installing refrigeration systems using a thermostatic expansion valve, it is a relatively common task to measure the superheat value of the refrigerant leaving the evaporator. However, there is a major consideration when using this measurement to analyze the operation of a system.
In many aspects the first part of a job is like detective work — not only does a technician need to identify the problem but he also must determine its root cause. A good initial step is to visually inspect the entire system.
Many refrigeration systems are installed using an outdoor air-cooled condenser. When these systems are installed in a climate where the outdoor temperature drops below 60°F, some means of preventing the condensing pressure from dropping too low must be incorporated into its design.
Replacing a compressor is neither simple for a technician nor inexpensive for the customer. Before replacing a compressor, a technician needs to ensure that it is truly defective. Unfortunately, sometimes good compressors get replaced as a result of a misdiagnosed problem.
When a refrigeration system fails, many times the cause can easily be diagnosed. However there are occasions when the cause cannot easily be determined - either the true cause is unclear or the technician is unsure of a problem. How do you work through these jobs? One method used by some techs is to “read and record.”
Actually, frost on the suction line only indicates that at the location where the frost is present, the suction line piping is below the dew point temperature of the surrounding ambient air and at or below 32°F. That’s it. It is neither an indication of a properly operating system nor a system defect.
The process of brazing ACR tubing is a common task for many refrigeration technicians. Although this is relatively simple, there are some system problems that can occur if some basic brazing procedures are not followed.
Accurately troubleshooting and repairing refrigeration systems requires technicians to use many specialty instruments. They base many of their diagnoses on what is read from these instruments. Relying on them to be consistently accurate day in and day out is a must. If these tools are inaccurate, more than likely the diagnoses will be inaccurate.