Field Notes
Plain-language notes on components, circuits and how to read a schematic, written for people at the bench, not for a classroom.
Field Notes
How NOT to Check the Refrigerant Charge!
There are many ways that technicians have tried to get around actually checking the charge of air conditioners and heat pumps with superheat and subcooling! I go into ...
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10 Reasons Why a Mini-Split Ductless Flare May Leak Refrigerant!
On a mini-split ductless system, two copper tubes are needed to transport the refrigerant. These copper tubes are referred to as the line set and they connect the indo...
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Checking the Charge of a Mini-Split Unit!
A question that I get asked frequently is “Can I check the charge of a mini-split ductless unit with superheat and subcooling the same way I do on a conventional air c...
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Is a Triple Evacuation Necessary for a Deep Vacuum?
Do you have to do a triple evacuation if you can achieve a deep vacuum by only doing a single evacuation? Remember that the target vacuum of 500 microns or lower must ...
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Measuring Negative Superheat on an Air Conditioner? (Quick Tips)
Can you Measure Negative Superheat on an air conditioner when checking the charge? The Answer is NO! Time to check your gauges and temp sensors for accuracy! To briefl...
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How to Tell if a TXV Has Lost Part of its Bulb Charge! (Quick Tip)
How do you tell if a TXV lost part of its bulb charge? If you are measuring a correct/high subcooling along with a high superheat and a low saturated temperature on th...
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