New Mexico HVAC Exam Prep FREE Sample Exam — Fixed Set

On a pressure-enthalpy diagram for a vapor-compression cycle, what do the two axes represent?

Temperature on the vertical axis and entropy on the horizontal axis, so every heat transfer process in the cycle is read as a change in entropy alone

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Pressure on the horizontal axis and volume on the vertical axis, with enthalpy calculated afterward from a separate table for each plotted state point

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Suction pressure on one axis and discharge pressure on the other, so compressor ratio can be read directly without knowing any heat content values at all

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Pressure vertically and enthalpy horizontally

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A 3-ton R-410A split A/C cools poorly on a 92°F day. Readings: suction 98 psig, head 282 psig, suction superheat 24°F, liquid subcooling 3°F, compressor amps 78% of rated, evaporator coil clean, airflow verified at 400 cfm/ton, and no temperature drop across the liquid-line drier. What is the most likely cause?

Noncondensables trapped in the condenser after a poor evacuation, which would drive head pressure and subcooling well above normal rather than low

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Severely reduced evaporator airflow from a clogged filter or coil, which would pull superheat down toward 2–5°F instead of leaving it at 24°F

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A restricted liquid-line filter drier, which would show a measurable temperature drop and often frost at the drier outlet while subcooling stayed high

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Low refrigerant charge

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Why does a cubic foot of propane need far more combustion air by volume than a cubic foot of natural gas, even though air needs per unit of heat are similar?

Propane molecules contain no carbon, so extra air is needed to supply carbon for a stable flame at the burner ports during normal operation

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Each cubic foot of propane carries much more heat and fuel to burn

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Natural gas burners use no primary or secondary air at all, so the comparison is between propane burners that need air and natural gas burners that burn in a vacuum jacket

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Propane air requirements are set by the tank pressure alone, so a cubic foot from a warm tank needs more air than the same cubic foot from a cold tank in winter

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One bedroom is always warm in cooling while the rest of the house is comfortable. Its register delivers about 18 CFM against a design of roughly 95 CFM; all other registers measure near design, system static pressure is normal, and the branch damper is verified open. In the attic, that bedroom’s flex duct makes a sharp bend at a truss and is visibly crushed where it crosses it. What is the most likely cause?

The kinked and crushed flex branch duct serving that room

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A system-wide airflow shortage from the blower, which would depress airflow at every register in the house rather than leave all but one branch at its design flow

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A closed zone damper starving one side of the house, ruled out because the branch damper is verified open and neighboring branches on the same trunk measure normally

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An undersized supply trunk for the whole system, which would show elevated static pressure and broadly weak registers instead of one crushed branch at normal static

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A 24 V contactor coil measures 15 ohms. Using Ohm’s law, about how much current does the coil draw when energized?

0.63 A

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1.6 A

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39 A

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360 A

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What defines a dedicated outdoor air system (DOAS)?

It is any rooftop unit whose nameplate includes the word 'dedicated' in the manufacturer's model number designation

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It is a transfer fan that moves air from a corridor into restrooms so those rooms need no exhaust duct of their own

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It is the kitchen makeup-air unit only, because no other system in a commercial building is ever dedicated to a single air stream

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A separate system that handles the outdoor (ventilation) air — often conditioning it to a neutral, dehumidified state — while other equipment handles the space's sensible loads

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Refrigerant piping passes through wood framing and runs exposed where it can be struck in a garage. What protection is required?

No protection is needed once the system holds pressure, because a passing pressure test also proves the piping can withstand vehicle impact

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Soft copper may be notched into the face of a stud without a plate, provided the notch is filled later with construction adhesive

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Piping in a garage should be buried in the concrete slab without a sleeve so vehicles cannot reach it under any circumstances

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Shield plates at framing penetrations where piping is close to the edge, and guards or placement that protects piping from physical damage.

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Air moves through a duct at 800 feet per minute, and the duct cross-sectional area is 1.5 square feet. What is the airflow volume?

The airflow volume is 800 cubic feet per minute.

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The airflow volume is 1,000 cubic feet per minute.

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The airflow volume is 12,600 cubic feet per minute.

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The airflow volume is 1,200 cubic feet per minute.

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Which state office licenses HVAC contractors in New Mexico?

The Construction Industries Division of the Regulation and Licensing Department licenses HVAC contractors in New Mexico

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HVAC contractors in New Mexico are licensed by the Public Regulation Commission through its transportation and utilities bureau

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HVAC contractors in New Mexico are licensed directly by the State Personnel Office under a general occupational permit program

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HVAC contractors in New Mexico are licensed by each county clerk in the county where the contractor maintains its main office

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Why should a contractor compare the estimate with final job costs on every completed project?

To satisfy a supplier requirement that estimates be filed with the wholesaler before the next material order is placed

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To set the amount of retainage on the next unrelated project for a different owner in a different market

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To improve future estimates and identify recurring cost errors

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To determine each employee's income tax withholding for the final payroll of the completed project

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SCENARIO (computed): A job’s total cost is $80,000. The contractor wants a selling price that yields a 25 percent margin on the selling price. What price achieves that margin?

A price of $96,000 achieves a 25 percent margin on the selling price for a job costing $80,000 in total, since adding one quarter of cost is the standard margin formula

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A price of $100,000 achieves a 25 percent margin on the selling price, since cost divided by one minus the margin gives the required price for this job's figures

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A price of $106,667 achieves a 25 percent margin on the selling price

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A price of $120,000 achieves a 25 percent margin on the selling price, since margin is computed by doubling the markup percentage and adding it to cost

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On a duct layout, a small diamond symbol on a branch duct is noted as a volume damper, and the branch serves a room that is overheating. What does that symbol tell the balancing technician?

An adjustable damper at that location can throttle the branch

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The branch contains a fire damper that must be removed from the airstream before any additional cooling can reach the overheated room

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The diamond marks a test port where static pressure is recorded once at startup and the branch airflow itself can never be adjusted afterward

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The branch is a spare takeoff capped inside the main, and the overheating must be corrected by increasing total fan speed for the whole system

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New Mexico HVAC Exam Prep FREE Sample Exam — Fixed Set

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