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.
Working safely should be a technician’s No. 1 priority; especially while working around electrical circuits and devices. Electricity is a powerful force that could kill or cause severe harm if mishandled. A technician must always be aware of this potential hazard.
Refrigeration technicians carry refrigerant in non-refillable cylinders on their service vehicles every day. While these cylinders are considered relatively safe, there are some hazards associated with transportation and storage, and when removing refrigerant. Mishandling or improper use can lead to injury and/or property damage.
The required oil charge for a system is basically a factor of the amount of refrigerant in the system and the compressor’s oil pumping rate. The most common method of determining if oil needs to be added to a compressor is to observe the compressor’s oil sight glass. But what if the compressor doesn’t have an oil sight glass?
Servicing and maintaining refrigeration systems requires a technician with a unique set of skills. Not only must a technician be proficient in the refrigerant cycle and all of its components, they also must be knowledgeable in many other trades.
Certifications offer many benefits to a technician. First, taking a certification exam demonstrates that a technician is serious about his trade and, more importantly, if passed, that he has achieved a high level of expertise. Certifications can also be used as a self-check to identify areas of weakness or strength.