Articles by John Tomczyk

The Professor: Crankcase Heaters

Coping With Refrigerant Migration
March 31, 2014

Migration of refrigerant to the compressor’s crankcase during an off cycle is a serious problem, as significant compressor damage can occur if the problem is not remedied. 


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The Professor: Understanding, Avoiding Transformer Burnouts

Solving Low-Voltage Power-Consuming Faults
March 3, 2014

This column will try to explain the voltages associated with the high or wild leg coming from the secondary of a Delta service transformer. 


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The Professor: ‘Wye’ or ‘Star’ Configurations

A Look at Electrical Service Transformers
February 3, 2014

John Tomczyk discusses the Wye or Star configuration of the three-phase electrical service, which usually delivers four wires to the building.


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The Professor: Low Ambient Controls Reduce Head Pressure

Control Is a Style of Head-Pressure Control Valve
January 6, 2014

When refrigeration systems are exposed to low-ambient conditions, the condensing pressure (head pressure) will fall. If the head pressure gets too low, the metering device will not have enough pressure drop across it to operate properly.


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The Professor: TXV Dos and Don’ts

The Externally Equalized Thermostatic Expansion Valve
December 2, 2013

The thermostatic expansion valve (TXV or TEV) is a metering device located between the liquid line and the evaporator. 


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The Professor: Refrigerant Undercharge

Dealing With R-134a Shortfall in a System
November 4, 2013

John Tomczyk, Professor of HVACR at Ferris State University and co-author of Refrigeration and Air Conditioning Technology, discusses refrigerant undercharge.


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The Professor: Diagnosing Bad HVAC Compressor Valves

When Low Head and High Suction Pressures Collide
October 7, 2013
Many service technicians experience service calls where the compressor has both a low head pressure and a high suction pressure. Often, the refrigeration equipment is still running, but the product temperature is suffering about 7-10°F.


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The Professor: An Overcharge of Refrigerant

Knowing Symptoms Can Lead to Solutions
September 2, 2013
It is the system check sheet that will tell the service technician whether a system is overcharged or not. Service technicians must install pressure gauges and thermistors — or some other sort of temperature-sensing devices — in order to systematically troubleshoot a refrigeration system correctly.


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The Professor: Flooding and Slugging of Compressors

Understanding the Terms Critical to Troubleshooting
August 5, 2013

Clear, concise, and accurate communication between service technicians, parts suppliers, customers, and the home shop is rapidly gaining importance as the HVACR field transitions and becomes more technically oriented.


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The Professor: Recognizing, Solving Refrigerant Migration

Eliminating Refrigerant from the Compressor’s Suction Line or Crankcase
July 1, 2013

During the off cycle, or especially during a long shutdown, refrigerant will want to travel, or migrate, to a place where the pressure is the lowest. 


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