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.
While repairing refrigeration equipment, technicians sometimes come up with unique methods of solving problems. Many of these are used again and again and become known as “tricks of the trade.” When a bunch of technicians get together, they oftentimes enjoy sharing new tricks they learned or developed recently. It’s like a badge of honor.
When multiple compressors are piped together with a common
suction and discharge header - such as with the arrangement of a parallel rack
configuration - oil return to each compressor is a major concern. Typical oil
recirculation rates are dependent on three factors.
The actual frequency and tasks performed will vary from system to system. However, here are some generic maintenance tasks which can be applied to many refrigeration systems. These tasks can be divided into two groups: one for maintaining the cabinet and one for maintaining the refrigeration system.
We all, at one time or another, come upon a system that is quite difficult to repair or to troubleshoot. This can be a very stressful experience. Different technicians have different ways of handling this stress. Some throw tools. Some talk to themselves. A better way of handling this stress is to first take a break.
Refrigeration systems utilizing an outdoor air-cooled condenser located in an area where the outdoor temperature can drop below approximately 70°F must be designed to prevent the system’s discharge pressure from dropping too low. There are several different methods that can be used to accomplish this task.
Many single-phase motors used on refrigeration systems will incorporate some type of capacitor. They will either use a start capacitor or a run capacitor. Some motors will even use both. Troubleshooting the operation of these motors requires a technician to know how to test both run and start capacitors.
Although a capillary tube can become totally restricted, a far more common problem is when it becomes partially restricted, allowing some refrigerant to flow into the evaporator but not enough to satisfy the requirements of the system. This seemingly easy problem to diagnose is actually rather tricky at times.
Thermostatic expansion valves (TXV) are responsible for metering the proper amount of refrigerant into an evaporator coil. When they fail, they either cause the evaporator to be flooded (overfed) or starved (underfed) for refrigerant. Read more and find out how to diagnose a defective TXV.
Less flash gas equals a higher net refrigerating effect and a more efficient system. Many designers reduce the amount of flash gas by additionally subcooling the liquid refrigerant entering the metering device. This lowers the refrigerant temperature; meaning less refrigerant will flash off to cool itself down to the evaporating temperature.