NATE AC Installation study plan

Define design operating conditions for cooling and heating cycles, including entering dry-bulb and wet-bulb, outdoor ambient, and indoor relative humidity targets.

Convert between gauge pressure, absolute pressure, and saturation temperatures using a pressure-temperature chart for R-410A and R-32 without a calculator aid.

Explain how airflow (cfm per ton), return-air temperature, and condenser ambient shift the operating envelope of a system.

Identify the instruments used to establish operating conditions: manifold gauges, digital psychrometer, clamp meter, manometer, and infrared thermometer, and state what each reading proves.

Calculate target superheat from indoor wet-bulb and outdoor dry-bulb using a charging chart, then compare it against measured superheat.

Calculate subcooling from condensing saturation temperature and liquid-line temperature, and state the acceptable target range for a TXV system.

Describe how a restricted liquid line, an overcharged system, and an undercharged system each move superheat and subcooling in opposite directions.

Diagram the refrigeration cycle on a pressure-enthalpy sketch and label the state of refrigerant at four points.

Identify the function and failure signature of the compressor, condenser coil, evaporator coil, metering device, filter drier, and accumulator or receiver.

Compare TXV, fixed orifice, and EEV metering devices on how they respond to load changes and where each is applied.

Sequence the installation steps for line-set routing, brazing with nitrogen purge, pressure testing, and triple evacuation to 500 microns.

Explain the purpose of a filter drier, a liquid-line sight glass, and a crankcase heater, and state what each protects.

Read a unit nameplate and extract minimum circuit ampacity, maximum overcurrent protection, rated voltage, phase, and refrigerant charge.

Calculate the required conductor ampacity and select the correct breaker size from the nameplate data for three sample units.

Identify the function of the contactor, run capacitor, start capacitor and relay, transformer, and disconnect, and recognize their common failure symptoms.

Explain proper lockout/tagout and safe capacitor discharge procedure before servicing electrical components.

Measure line voltage, control voltage, and running amperage on a live circuit and compare each reading against nameplate tolerances.

Test a run capacitor with a meter, calculate the acceptable microfarad range from its rating, and diagnose a failed capacitor.

Trace a low-voltage control circuit from thermostat through the transformer, contactor coil, and safety switches, and identify where an open circuit stops the call for cooling.

Verify equipment grounding, polarity, and bonding requirements at the disconnect and at the unit.

Calculate temperature split (delta T) across the evaporator and compare against the manufacturer's target range for the measured indoor conditions.

Measure external static pressure across the air handler and use it to judge whether airflow is within the blower performance table.

Diagnose low airflow, high superheat, and high delta T as a set of correlated symptoms, and separate them from a low-charge pattern.

Explain the recovery, recycling, and evacuation requirements for refrigerant handling during service and how to verify a leak-free system.

Explain how outdoor air intake, return-air filtration, and duct sealing each affect indoor air quality and total system capacity.

Select an appropriate filter MERV rating for a residential application and state the trade-off between filtration and pressure drop.

Identify duct leakage, undersized returns, and unbalanced room airflow as causes of comfort complaints, and describe how to measure and correct each.

Verify condensate drainage, trap depth, and slope as they relate to humidity control and mold prevention.

Re-take timed practice sets for every domain and log every missed question by domain and root-cause category.

Re-study the two lowest-scoring domains from the logged results until error rates drop below 15 percent.

Recite from memory the key formulas and target values: superheat method, subcooling method, delta T, MCA and MOP selection, and capacitor tolerance.

Simulate a full installation walk-through from rough-in to final performance verification, narrating each measurement and its acceptance criterion.