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.

One contaminant that must be removed from a refrigeration system before refrigerant can be added is water vapor. If water vapor is left trapped in a system, it can lead to some serious problems. Technicians will typically reduce the system’s pressure to about 500 microns to remove this water vapor.

There are several ways we can get answers to our questions. The easiest way is to just ask someone who has more experience with the system or component. However, if an answer does not make sense or is unclear, we should not just simply accept it as fact, but should ask it again or ask “why.”

Thermistors are one type of temperature sensor used on electronic control systems. Technicians servicing these control systems need to be able to test the operation and accuracy of these sensors. A defective thermistor can easily cause a controller to not operate correctly.