Louisiana HVAC Exam Prep FREE Sample Exam — Fixed Set

After a hermetic compressor burnout, a replacement compressor is installed. Beyond changing the liquid-line drier, what contamination follow-up protects the new compressor?

Test the oil/system for acid and fit suction-side filtration, then recheck and remove it as cleanup is confirmed

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Do nothing further, because a single liquid-line drier change always removes all acid and debris left in the system by a hermetic motor burnout

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Flush the new compressor itself with solvent before startup, because flushing a hermetic unit internally is the standard way to remove burnout contamination

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Raise the operating superheat substantially for the first month, because running hot is an accepted substitute for removing acid from a contaminated system

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A homeowner asks why the new R-454B air handler runs its blower for a while after a leak sensor trips, even though cooling has stopped. What is the correct explanation?

The blower is removing residual heat from the electric heat strips, a normal cool-down sequence that happens to coincide with the sensor alarm event

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The blower pressurizes the duct system so refrigerant vapor is forced back through the leak point into the coil, resealing the system temporarily

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The blower dilutes and disperses leaked refrigerant through the duct system so room concentration stays low

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The blower run is a fault in itself, because mitigation design requires the air handler to shut down every moving part the instant a sensor trips

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A 15 kW electric furnace has three equal 5 kW elements. On a heat call all sequencer contacts close, supply voltage is correct, but total current draw equals only two-thirds of the expected value and supply air is cooler than normal. What is the most likely fault?

One heating element is open and producing no heat

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The sequencer is energizing an extra element

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The blower is running too fast for any heating to occur

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The thermostat is set to emergency heat on a gas furnace

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Which set of duct locations must all be included when a duct system is sealed to its specified class?

Only the transverse joints, because longitudinal seams are factory-sealed

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Transverse joints, longitudinal seams, and branch tap-ins and other duct wall penetrations

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Only the connections at the air handler, because the rest of the system leaks negligibly

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Only fittings, because straight duct sections never leak at their seams

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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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CSST runs through a house with several metal systems. The bonding jumper for the CSST is installed primarily to:

Carry the normal return current of the HVAC circuits, so that a separate equipment grounding conductor is no longer needed for the furnace

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Replace the grounding electrode conductor for the whole house, because bonding the gas tubing satisfies every grounding requirement by itself

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Equalize electrical potential and reduce arcing damage from induced voltage

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Prevent corrosion of the tubing by draining stray direct current from the gas line into the soil outside the building foundation wall

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A system is verified to have solid liquid at the sight glass with correct subcooling, yet the moisture indicator shows wet. The correct response is:

Ignore it, because a clear glass proves the system is dry under all conditions, including after the system has been opened for service, evacuated briefly, and returned to operation with its original drier still in place

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Replace the liquid-line drier (and investigate how moisture entered), because the indicator reports moisture independently of bubbles

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Remove charge until bubbles appear

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Replace the expansion valve with a larger size

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Windows condense heavily on cold winter mornings in a tight new home with a large family, showers, and cooking. Indoor humidity reads 48%. What is the most likely diagnosis?

The humidifier is undersized, so raising indoor humidity further will warm the window glass and stop the condensation from forming

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The windows are leaking refrigerant, because condensation on glass is a recognized sign of a cooling-system charge problem in winter

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The furnace is oversized for cooling, which explains winter window moisture even though the cooling system is not operating at all

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Indoor moisture generation exceeds removal, so humidity must be lowered and ventilation or exhaust increased rather than adding humidification.

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A new refrigerant line set is to be pressure tested for leaks before evacuation. Which medium and practice are correct?

Use oxygen from a cutting torch tank

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Use compressed shop air without a regulator

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Use dry nitrogen with a regulator, test at the specified pressure, and use an electronic detector or bubbles to check joints

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Pressurize with refrigerant alone to maximum pressure

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Why do many manufacturers require product registration within a set window after installation for extended parts coverage?

Registration is purely a marketing enrollment that has no effect on the duration or terms of the equipment's parts coverage

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Registration links the serial number to the install date and owner, activating the longer registered warranty term

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The unregistered warranty is longer, so registration is offered mainly to shorten coverage in exchange for email promotions

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Registration transfers the warranty to the installing company, so the homeowner no longer owns the coverage on their equipment

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A variable-speed drive slows a chilled-water pump to 90% of full speed. Using the pump affinity laws, about how much pump power is saved?

About 3%, because pump power falls only in direct one-to-one proportion to the drop in pump rotational speed

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About 10%, because pump power falls in proportion to the square of the speed ratio at reduced flow conditions

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About 19%, because pump head and pump power always change by exactly the same percentage as each other

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About 27%, because power varies with the cube of speed: 0.9 cubed is about 0.73 of full power

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Two estimators price the same furnace change-out. One counts every fitting and hanger from the drawings; the other guesses quantities from memory. What practice distinguishes the first estimator?

Applying a single company-wide markup before any quantities for the specific job have been determined at all

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Relying on the supplier to set the contract price after the proposal has already been presented to the owner

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Performing a quantity takeoff

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Using last year's material prices without checking whether sizes, counts, or current costs have changed

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Louisiana HVAC Exam Prep FREE Sample Exam — Fixed Set

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