HVAC worker cheat sheets built for repeat field use in United States
Built for United States field work where techs bounce between split systems, furnaces, heat pumps, package units, and mixed local code adoption. These are original quick-reference sheets for techs and installers. Use them for faster diagnosis, safer handoffs, and cleaner callbacks. Always follow manufacturer data, lockout/tagout procedure, and local code when the cheat sheet and the equipment disagree.
- Expect CFM, in. w.c., delta-T in F, and airflow targets tied to fan tables or ECM profiles.
- Charging notes usually pair superheat or subcooling with line temperatures and saturation readings.
- Combustion calls often need temperature rise, manifold pressure, venting, and flame-sense proof in the same ticket.
- No-cool and frozen-coil calls driven by airflow misses, dirty filters, and humidity load.
- Gas furnace sequence faults in winter and shoulder-season heat pump changeover complaints.
- Rooftop and package-unit calls where electrical, airflow, and charge all overlap.
- Mechanical, electrical, and fuel-gas code enforcement changes by state and city, so local adoption always wins.
- EPA refrigerant handling, manufacturer charging data, and documented combustion safety checks stay non-negotiable.
- When a call involves venting, gas pressure, or repeated safeties, the write-up should be as solid as the repair.
- Before quoting duct modifications or blower changes.
- During no-cool callbacks where one number is trying to tell the whole story.
- When mentoring junior techs through structured diagnostic ladders.
Airflow references your crew can use on the next call
Airflow, CFM, and Static Pressure Quick Check
Use this when you have hot and cold rooms, noisy returns, frozen coils, or a unit that feels starved for air.
Cooling Delta-T and Split Temperature Sanity Check
A quick field reference for using return-to-supply temperature difference without over-reading one number.
Electrical references your crew can use on the next call
24V Control Circuit Troubleshooting Ladder
Use this for no-cool, no-heat, or no-fan calls when the low-voltage circuit is the likely control failure point.
Capacitor and Contactor Field Checks
A fast reference for the two outdoor-unit failures you can lose a day on if you skip the basics.
Refrigeration references your crew can use on the next call
Heating references your crew can use on the next call
Heat Pump Defrost Troubleshooting Cheat Sheet
A field-side reference for when the outdoor unit is icing, short-defrosting, or never defrosting at all.
Gas Furnace Sequence of Operation and Safeties
A quick ladder for no-heat calls so you can prove exactly where the sequence breaks.