Hawaii C-52 HVAC Exam Prep FREE Sample Exam — Fixed Set

Where should a suction-line filter be used, and what caution applies to leaving it in place permanently?

It is required permanently on every new installation, because suction filtration is the only protection a compressor has against moisture in the refrigerant charge

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It is mainly a temporary cleanup device after a burnout or contamination event, and a permanent one can cause excessive suction pressure drop

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It belongs in the liquid line ahead of the drier, because suction filters and liquid driers perform the same job and are installed in the same location interchangeably

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It should never be used after a burnout, because the acid and debris from a burnout can only be removed by replacing the compressor and the evaporator coil

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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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An air handler above a finished ceiling cools normally for hours, then stops with its condensate safety switch open, restarting after the water level slowly falls. The primary drain flows freely when tested with a full pan of water poured in at once. What subtle fault best fits intermittent trips under real operation?

The switch is defective whenever it opens, so it should be replaced without further checks, without inspecting the drain line, the trap, or the water level in the pan itself

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The refrigerant charge rises during the day and forces water out of the pan

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The unit is producing no condensate, so the switch must be reading a false level

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A partially restricted drain or marginal trap holds drainage just behind production during long humid runs, slowly raising the level until the switch trips

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Besides compressor speed control, which coordinated controls does a typical inverter ductless system use to match capacity smoothly?

A fixed orifice and a single-speed outdoor fan switched only on and off, with no modulation of either airflow or refrigerant flow as the compressor changes speed to follow the changing load

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A gas valve that stages burners to assist the compressor

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A mechanical timer that forces full-speed runs every ten minutes

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Variable-speed indoor and outdoor fans and an electronic expansion valve, all adjusted by the control board together with compressor speed

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A 96% AFUE furnace is installed in a basement. Its flue gases are relatively cool and the vent system is designed to operate under positive pressure with a condensate drain at the furnace. How should its venting be handled?

Vent it into an existing unlined masonry chimney with no corrosion-resistant liner, relying on the chimney's natural draft to carry the cool flue gases out

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Use a single-wall metal connector into a Type B vent shared with a water heater

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Vent it with the manufacturer-approved sealed plastic vent system and drain the condensate as directed

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Let it vent into the basement and rely on dilution air to carry products out

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A return grille that is too small for the required CFM will most likely cause:

Lower velocity and quieter operation

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No change in static pressure

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High velocity, noise, and increased pressure drop

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Higher refrigerant superheat directly, with no change in airflow or noise

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Three compressors serve a process cooling load. The lead compressor runs continuously while the others short-cycle. What staging change best evens wear and stabilizes capacity?

Disable the lag compressors so the lead machine handles every load alone

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Rotate the lead position on a schedule or by run hours and enforce anti-short-cycle timing between starts

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Remove all start delays and anti-short-cycle timers so lag machines can start instantly whenever suction pressure moves even slightly

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Wire all three contactors together so every compressor starts and stops at the same instant

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A furnace clocks at an input 20% above its rating plate after a gas-valve replacement. The most likely setup causes are:

Manifold pressure set too high or wrong-size orifices installed

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A vent connector one size larger than the minimum, because a larger vent increases draft and pulls extra gas through the burner orifices

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A sediment trap with a long capped leg, because the trap volume adds a reserve of gas that the meter counts as additional furnace input

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A thermostat set several degrees above room temperature, because a larger temperature difference makes the gas valve deliver more fuel per hour

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A protective-environment room for an immunocompromised patient needs the opposite relationship from an isolation room. What is it, and why?

It is kept negative so any microbes generated by the patient are drawn inward and cannot reach the supply diffuser in the ceiling

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It is kept positive with well-filtered supply air so corridor air and its contaminants are kept out of the room.

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It is kept at exactly the same pressure as the corridor, because pressure differences of any kind are prohibited around immunocompromised patients

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It is ventilated only with unfiltered outdoor air, because filtration removes the natural microbes that help such patients build immunity

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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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An 80% furnace is replaced with a 96% condensing furnace reusing the old B-vent chimney path. What venting change is required?

The B-vent can be kept unchanged because furnace vent categories are interchangeable whenever the vent diameter stays the same

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The old vent can be kept if the installer raises the flue temperature by removing the new furnace's secondary heat exchanger

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The new furnace needs its listed plastic or approved vent system; its cool, condensing exhaust cannot use the old B-vent as-is

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The chimney should be capped and the new furnace vented into the attic space, where its exhaust is too cool to cause any harm

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A single-phase compressor hums, draws high current, and trips its overload without starting, while a second identical unit on the same panel starts normally. The run capacitor tests well below its rated capacitance. What is the correct repair?

Replace the run capacitor with one of the same capacitance and voltage rating and retest starting

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Replace the compressor, because a humming compressor that trips overload has locked rotors in every such case

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Install a larger breaker, because raising the trip point lets the compressor pull through its difficult starting period

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Add refrigerant to lower the starting load, because low charge is the usual reason a compressor hums without starting

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Hawaii C-52 HVAC Exam Prep FREE Sample Exam — Fixed Set

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