Articles by John Tomczyk

The Professor: The Scroll Compressor - A History

By John Tomczyk
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This is the first in a series of three articles covering the scroll compressor. This first article covers the history of the scroll compressor along with the scroll compressor operation.
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The Professor: Air Conditioning System Troubleshooting

By John Tomczyk
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This is the final article in a series covering inefficient compressors, noncondensibles in the system, low and high condenser entering air temperatures, and different metering devices as they apply to troubleshooting air conditioning systems.
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The Professor: Systematic Troubleshooting

By John Tomczyk
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This is the third in a series of columns on systematic air conditioning troubleshooting and diagnostics. This column deals with liquid subcooling, liquid and suction line restrictions, overcharges, and undercharges.
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The Professor: Diagnosing Air Conditioning Systems

By John Tomczyk
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This is the second of three columns on systematic air conditioning troubleshooting and diagnostics. The first appeared in the May 5 issue of The NEWS. The third part will appear in the July 7 issue. This article deals with modern evaporator and condenser designs to meet the new minimum 13 SEER requirements.
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The Professor: Diagnosing Air Conditioning Systems

By John Tomczyk
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This is the first of three columns on systematic air conditioning troubleshooting and diagnostics. It will deal with airside and the evaporator. In a/c system diagnostics, a service technician must realize that system problems fall mainly under two major categories: airside problems and refrigerant cycle problems.
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The Professor: Troubleshooting With Voltmeter

By John Tomczyk
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It is of utmost importance for service technicians to understand voltage troubleshooting when servicing HVAC and refrigeration equipment. The majority of service problems are electrical problems, which usually cause mechanical problems. This article illustrates how to voltage troubleshoot using a voltmeter.
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The Professor: Restricted Metering Device

By John Tomczyk
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This column explores how a restricted metering device will affect system performance and efficiency. The system is a commercial refrigeration system employing a receiver and a thermostatic expansion valve (TXV) as the metering device. The refrigerant is R-134a.
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The Professor: Refrigerant Undercharge

By John Tomczyk
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My Jan. 14 column in The NEWS focused on system overcharges. This column will look at an undercharge of refrigerant. In the example to be used, we will look at a medium-temperature refrigeration system running on HFC-134a and having a thermal expansion valve (TXV) and liquid receiver.
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The Professor: System Overcharge

By John Tomczyk
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Many technicians have a tendency to add refrigerant to a refrigeration system simply because it is not cooling to its potential. Often, this overcharges the system with refrigerant and can make matters worse.
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More Systematic Troubleshooting

By John Tomczyk
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As you might recall, my Nov. 5 column focused on a restricted liquid line after the receiver. In this column, we will look at local cold spots or frost where the restriction occurs and issues related to bubbles in a sight glass.
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Twin Cities contractor Aabott Ferraro helped retrofit an older St. Paul home.

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NEWSMakers: Jeff Nusz

Jeff Nusz, president, Reitmeier HVAC Services, Tualatin, Oregon, joins the program to discuss how he modernized his website and gained new clients and more money because of it. We’ll go through the process of the change and much more.  Posted on Aug. 1.

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