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R-134a

The concept of superheat

October 19, 2021

We illustrated the concept of superheat in last week's article by boiling water and superheating steam in a moonshine still. This week we will apply this concept to refrigerant in an air conditioning system.  The still has been replaced with an evaporator. 
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Behavioral characteristics of various compressor types pt. 2

October 5, 2021

So now it is time to provide the correct answer along with information on why it is correct and also information on why the others are incorrect.
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Behavioral characteristics of various compressor types

September 21, 2021

When faced with a challenging A/C system problem, knowing what type of compressor you are dealing with can help streamline the diagnosis process. 
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The Humble Mechanic wants to see you at MACS

September 2, 2021

Charles Sanville, better known as the Humble Mechanic is MACS Keynote Speaker. Come see Charles on Thursday, September 30 at 11:30am at The Rosen Centre Hotel in Orlando, FL.
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MACS Tesla project

August 26, 2021

MACS is working on a project, to collect A/C charge information for Tesla vehicles, and we need your help!
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Field study: Incorrectly installed condensers

August 10, 2021

I have handled numerous tech calls involving older GM trucks with incorrectly installed condensers.  In preparation for this series of MACS blogs, I discovered a salvage truck with one of these condenser repairs.  This gave me the opportunity to duplicate the incorrect installation and look for pitfalls and solutions.
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Top three tips on orifice tube behavior

July 20, 2021

In the last four MACS blog articles we covered a lot of detailed information about orifice tube system behavior. We examined a system with a full refrigerant charge verses a 25% undercharge. Now it is time to condense it all down into three important takeaways.
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Low refrigerant charge and the search for real data part 4

July 13, 2021

When we examined the pressure readings and vent temperature readings last week, there was nothing showing up that indicated any charge issues (even operating with the 25% undercharge).
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Low refrigerant charge and the search for real data part 3

July 6, 2021

To place as much heat load on the system as possible, we turned the heat in the shop up on high and got it as hot as possible before beginning the test. When the temperature peaked at 89°, we began the test. We tried to keep it constant, but all the heat being generated by the engine in the test vehicle caused it to inch upward by 2.5° before the second test was concluded.
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Low refrigerant charge and the search for real data: part 2

June 29, 2021

The purpose of the test was to run an orifice tube system with a full refrigerant charge and then with a 25% undercharge and compare pressure readings and temperatures at strategic points in the system.
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