Michigan HVAC Exam Prep FREE Sample Exam — Fixed Set

A technician must adjust TXV superheat on a stable, fully loaded system. Which procedure is correct?

Turn the stem several full turns at once and read the superheat immediately, because a TXV reaches its new equilibrium within a few seconds of any adjustment

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Measure the superheat at the compressor inlet after a long suction line, because pressure drop and heat gain along that line have no effect on the reading obtained

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Adjust the valve while the system is pumped down and off, counting stem turns from fully closed, because superheat cannot be set under actual operating load conditions

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Measure superheat at the bulb location, turn the stem in small increments, and allow the system to stabilize between adjustments

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A system cools the air temperature adequately but humidity stays near 65%. Readings: airflow measured at 485 cfm/ton, air-side temperature split only 13°F, superheat 9°F, subcooling 10°F, pressures normal, coil clean, and condensate barely drips except on the hottest afternoons. What adjustment does the evidence support?

Install a larger evaporator coil, a major change that does nothing about air moving too fast for moisture to condense on the coil surface

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Increase blower speed further to move more air across the coil, which would raise coil temperature even more and strip off still less moisture

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Add refrigerant to drop the suction pressure and coil temperature, which would corrupt the currently correct superheat and subcooling values

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Reduce blower speed to lower airflow per ton

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A furnace overheats on limit most cycles. Temperature rise is 88°F, the filter is clean, ducts are open, the blower motor runs but sounds labored and its capacitor measures 3.1 µF against a 10 µF rating; motor amps are elevated and the motor shell is very hot after short runs. Gas input is correct. What is the most likely cause?

A weak blower run capacitor

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A limit switch weakened by age and opening early, which is contradicted by the genuinely high measured supply temperature at each trip

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Closed supply registers throughout the house, which were all found open during the airflow survey of the duct system

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An overfired burner section, which is excluded because the clocked gas input matches the nameplate firing rate exactly

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A heat pump compressor fails in mid-winter and the technician sets the thermostat to emergency heat while parts are ordered. What changes in system operation?

The heat pump runs at double capacity to compensate

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Defrost cycles double in frequency to protect the coil

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The compressor is locked out and the auxiliary heat becomes the sole heat source

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The reversing valve is removed from the refrigerant circuit permanently and replaced with a straight section of copper tubing

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A homeowner expects zoning dampers to cure weak airflow that exists today with all rooms calling, on an undersized common trunk. Why will zoning alone disappoint?

Zoning increases the capacity of the common trunk, so weak airflow with all zones calling proves the trunk is oversized rather than undersized for the equipment

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Dampers add resistance and only redistribute air; they do not enlarge a trunk that is already too small for total airflow

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Weak airflow with all zones calling is caused by the zone panel withholding blower speed, and removing the panel restores full trunk capacity without any duct change at all

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Zoning cures total airflow problems whenever one room is weak, because closing other branches permanently is an accepted substitute for sizing the common duct to the equipment

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For reliable building pressure control, where should the indoor pressure sensor reference be placed?

Inside the supply duct, where pressure is highest and easiest to read

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In a representative interior location away from doors, diffusers, and direct drafts, referenced to a stable outdoor pressure tap shielded from wind

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Directly in the blast of an entrance door that opens frequently

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Outdoors on the roof in a fully exposed location where wind gusts strike the pressure tap directly and the reading follows every change in wind speed and direction

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An appliance shutoff must be serviceable after the furnace is set in a tight closet. Best placement is:

Behind the furnace against the rear wall, because a shutoff is considered accessible if it can be reached after the appliance is pulled out

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In the attic above the closet, because the valve only needs to be reachable by a technician carrying a ladder during an emergency shutoff

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Downstream of the flexible connector at the valve inlet, because placing it there shortens the length of pipe that remains live during service

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Upstream of the connector, in the same room, reachable without moving the appliance

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An ERV’s measured outdoor airflow has fallen 25% over a year while fan energy has risen, and the wheel still rotates freely. What is the most likely service finding?

The wheel has absorbed so much moisture that it has become heavier, and drying it with a heat gun restores the original airflow, a drying service the manufacturer supposedly recommends performing at every seasonal changeover without exception

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Loaded filters and a fouled energy-transfer core are raising pressure drop, so the fans move less air against the added resistance

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The exhaust and supply fans have exchanged rotation directions, which always shows up gradually over about a year's operation

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The outdoor-air intake has grown larger through damper wear, letting in more air than the flow station was designed to measure

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A crew is about to work from a scaffold erected beside an air handler. Which condition must be met before the scaffold is used each shift?

The scaffold only needs a fresh inspection when it is first erected, after which daily conditions such as weather and impacts cannot affect its safety

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Workers may use the scaffold while it is still being moved into position, provided they hold the frame and keep their weight near the casters

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Guardrails can be left off the top level whenever ductwork is being passed up, because material handling temporarily overrides fall protection needs

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A competent person inspects it and footing and planking are sound

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A customer wants the new high-efficiency outdoor unit paired with their 15-year-old indoor coil to save money. What is the most accurate contractor response?

The full rated efficiency will still be achieved because efficiency is determined entirely by the outdoor unit's compressor design

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The combination will actually exceed its rating, since older coils have heavier copper that transfers heat better than new coils

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The system may run, but the rated efficiency and capacity cannot be claimed and performance and warranty coverage are at risk

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Efficiency will be unaffected as long as the refrigerant type is the same in both the old coil and the new outdoor unit

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Nine members of the Board of Mechanical Rules attend a meeting at which a decision must be reached. How many affirmative votes does a board decision require at that meeting?

Six votes; a decision requires two-thirds of the members attending, and two-thirds of 9 attending members is 6.

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Five votes, because a simple majority of the members attending decides any board question.

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Eight votes, because the quorum number is also the number of votes a decision requires.

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Ten votes, because two-thirds of the board's total membership of 15 is required for every decision after the licensee obtains a one-time special authorization from the department for that particular installation and pays an added processing charge.

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Appliances totaling 80,000 Btu/h use the outdoor two-opening method with vertical ducts. What is the minimum free area of each opening?

Each opening needs at least 40 square inches of free area with vertical ducts

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Each opening needs at least 80 square inches of free area with vertical ducts

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Each opening needs at least 20 square inches of free area with vertical ducts

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Each opening needs at least 100 square inches of free area with vertical ducts

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Michigan HVAC Exam Prep FREE Sample Exam — Fixed Set

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