A closer look at a refrigeration system with an overcharge of refrigerant. 

Diagnosing an air conditioning system isn’t easy. A service technician must be a trained professional to diagnose a system efficiently and correctly — no longer can a tech rely on rules of thumb for coil temperatures or pressures. 

Compressor performance curves can provide a service technician with the Btu pumping rate (capacity), mass flow rates, operating amperage, and operating wattage of a compressor when the suction pressure and head pressure are known for the system. 

A refrigeration system’s compression or pressure ratio is defined as the absolute discharge pressure divided by the absolute suction pressure. Calculating this ratio can be a big help when it comes to troubleshooting a system.

Last month’s article covered a 400-series refrigerant blend’s total temperature glide, effective temperature glide, fractionation, superheat, subcooling, and average evaporator and condensing temperatures using a pressure/temperature chart. This article deals with system pressure drops and net temperature glide in a refrigeration and/or air conditioning system.

System design, performance, and service conditions must be evaluated when retrofitting with a zeotropic or near-azeotropic refrigerant blend. Always follow the refrigerant manufacturer’s retrofit guidelines before retrofitting with any refrigerant, or system performance could be affected and/or injury may occur.

Using variable frequency drives (VFDs) to control the speed of a compressor can provide improved occupant comfort and quieter operation in air conditioning and heat pump applications. Always consult with the specific compressor manufacturer before using a VFD controller on any compressor.

Technicians should make a list of the causes that could be blamed for this failure and, once the system is up and running, eliminate them, one by one. 

If air gets into a system, it will collect in the top of the condenser and be trapped. Here are eight symptoms of air in a refrigeration system.