Metering Device (TXV, Piston, EEV)
TXVs, fixed orifices and electronic expansion valves.
Checking Heat Pump Charge in Heat Mode: What Works in Winter
Why superheat and subcooling targets from cooling don't apply in heat mode, what manufacturers recommend for winter charging, and how to tell if a heat pump is low on charge in heating.
Servicing R-22 Systems in 2026: Recharging, Retrofits and Repair-or-Replace
What you can and can't do with an R-22 air conditioner or heat pump today, where R-22 comes from now, how retrofit refrigerants work, and how to help a customer decide between repair and replacement.
Frozen Evaporator Coil: Causes, Safe Thawing and What to Check
Why AC evaporator coils freeze, how to thaw one safely, and the order to check airflow, charge and metering once it's thawed.
Superheat vs. Subcooling: What Each Tells You and When to Charge by Which
What superheat and subcooling measure, how to take them, which one to charge by for TXV and fixed-orifice systems, and how to read them together.