Refrigerant & Charging

PT charts, superheat and subcooling, R-454B and R-32.

By symptom:AC Not CoolingFrozen CoilHeat Pump Blowing Cold AirRefrigerant Leak
By part:CompressorEvaporator CoilMetering Device (TXV, Piston, EEV)Line SetReversing Valve

How to Find a Refrigerant Leak: Methods, Common Spots and the Standing Pressure Test

A step-by-step leak search for AC and heat pump systems, the leak detection methods and where each works best, the most common leak spots, and how to confirm the repair.

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.

How to Read a PT Chart: Saturation, Dew Point, Bubble Point and Glide

Use a pressure-temperature chart to turn gauge pressure into saturation temperature, and know when to use dew point vs. bubble point on blends.

R-32 vs. R-454B: The Differences That Matter on a Service Call

Side-by-side comparison of R-32 and R-454B for techs, covering composition, GWP, pressures, glide, discharge temperature, charging and safety.

R-454B for Technicians: Pressures, Charging, Tools and Safety

What changes when you service R-454B, the A2L that replaced R-410A in many new systems, from glide and liquid charging to A2L tools and leak sensors.

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.

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.

HFC Rules in 2026: What the AIM Act Means for HVAC Techs

The 2026 state of the HFC phasedown, the R-410A installation rule change, and the new 15-pound leak-repair rules, explained for service techs.

Tools, charts and checklists

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