Articles by John Tomczyk

The Professor: Diagnosing Bad HVAC Compressor Valves

When Low Head and High Suction Pressures Collide
By John Tomczyk
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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
By John Tomczyk
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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
By John Tomczyk
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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
By John Tomczyk
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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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The Professor: Leak Checking a Water-Cooled Condenser

Locating Refrigeration Cycle Leaks May Be Easier Than You Think
By John Tomczyk
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When a refrigeration system has lost most of its refrigerant charge in a short period of time, the leak is probably significant and should be easy to find.


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The Professor: Three-Phase Motor Voltage Unbalance

Troubleshooting an Overheating Compressor
By John Tomczyk
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Compressor overheating is usually caused from high compression ratios. High compression ratios can be caused from a combination of high condensing pressures (temperatures) and low suction (evaporating) pressures.


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The Professor: Controlling Evaporator, Defrost Efficiency

By John Tomczyk
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The evaporator is a major component in the refrigeration system, and an efficient evaporator plays a key role in saving energy. 


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The Professor: Partially Restricted Filter Driers

By John Tomczyk
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We are going to look at issues related to a partially restricted filter/drier. For this purpose I have included a service checklist as well as a number of illustrations.


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The Professor: Compressor Overheating

By John Tomczyk
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Compressor overheating is often referred to as the HVACR industry’s most serious field problem.


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The Professor: Compressor Superheated Discharge Temps

By John Tomczyk
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The compressor’s superheated discharge temperature can tell the service technician what is going on inside a refrigeration or air conditioning system. The compressor’s discharge temperature is a reflection of the hottest part of a refrigeration system, and there are limits as to how hot a discharge temperature should be.


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Joseph Groh, an industry veteran boasting 35 years of HVAC experience, discusses the 2008 bicycle accident that cut his career tragically short, and how the Joseph S. Groh Foundation is his way of giving back to the construction trade. Posted on Aug. 22.

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