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Diagnostics
Refrigerant Overcharge vs Undercharge: How to Tell
How to tell if an AC is overcharged or undercharged using superheat and subcooling, the symptoms of each, and why airflow must be verified before touching the charge.
HVAC Delta T: Normal Range and What a Bad Reading Means
What Delta T (temperature split) means for AC and furnaces, the normal ranges, how to measure it, and what high or low readings tell you about a system.
Superheat vs Subcooling: A Field Guide for HVAC Techs
What superheat and subcooling mean, how to measure each, normal target ranges for TXV and fixed-orifice systems, and what readings tell you about refrigerant charge.
HVAC Static Pressure: How to Test It and What the Numbers Mean
How to measure total external static pressure (TESP), the normal range for residential systems, and how high or low readings point to specific duct and equipment problems.