Multiple Choice Identify the letter of the choice that best
completes the statement or answers the question.
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1.
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The resistance to air flow of ducts, coils, filters and other surfaces is
called:
a. | velocity | c. | static pressure | b. | total pressure | d. | stratification |
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2.
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Using an ohmmeter, you measure zero (0) ohms between "C" and
"S" terminals. This most likely means:
a. | start winding is open | c. | internal overload is open | b. | start winding is
shorted | d. | start winding is
good |
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3.
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A "start kit" for a compressor:
a. | decreases start winding resistance | c. | increases starting
torque | b. | increases start winding resistance | d. | decreases starting
torque |
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4.
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Which of the following could cause head pressure to rise (cooling mode)?
a. | clogged filter | c. | non-condensable in the system | b. | a frosted
evaporator | d. | plugged
filter/drier |
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5.
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How much heat (approximately) is produced by a 5 KW heater?
a. | 5000 | c. | 10000 | b. | 7500 | d. | 17000 |
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6.
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The point at which a heatpump produces exactly 100% of the structure heat loss
is called the:
a. | thermal balance point | c. | heating seasonal performance factor | b. | coefficient of
performance | d. | equalization
temperature |
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7.
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What instrument is used to measure static pressure?
a. | inclined manometer | c. | mercury manometer | b. | velometer | d. | anemometer |
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8.
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The purpose of the internal bleed port on some types of TXV is to:
a. | maintain full flow to the evaporator | c. | equalize pressures in the
"on" cycle | b. | compensate for evaporator pressure
drop | d. | equalize pressures in
the "off" cycle |
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9.
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Why must you energize the crankcase heat for at least 24 hours prior to starting
a compressor that has been off for a long time?
a. | reduce the oil viscosity | c. | warm the compressor for easier
starting | b. | reduce the amount of refrigerant trapped in the oil | d. | increase the oil
viscosity |
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10.
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One advantage of multi-tapped, direct drive PSC motors is:
a. | it is in constant operation | c. | the amp draw remains
constant | b. | CFM changes are easily made | d. | it moves more air than a belt drive |
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11.
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A device that removes the start capacitor from the circuit when a hermetic
compressor reaches about 80% operating sped is the:
a. | impedance relay | c. | run capacitor | b. | centrifugal switch | d. | potential relay |
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12.
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Which of the following can cause a frosted evaporator?
a. | bad compressor valves | c. | an undersized duct system | b. | high suction
pressure | d. | an overcharged
evaporator |
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13.
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When checking a compressor motor with an ohmmeter, the highest reading would be
from:
a. | start to common | c. | start to run | b. | main to run | d. | common to run |
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14.
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The most likely reason for a compressor to cycle on and off while the condenser
fan runs continuously is:
a. | low refrigerant charge | c. | open run winding | b. | low thermostat setting | d. | excessive load |
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15.
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A blower motor is cycling on and off with the thermostat fan switch set to
"on". The most likely cause is:
a. | start capacitor | c. | transformer | b. | motor overload | d. | wall thermostat |
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16.
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Which of the following could cause the limit switch to open the circuit?
a. | fan control is open | c. | gas valve stuck shut | b. | transformer is burned out | d. | cracked heat
exchanger |
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17.
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What is the most accurate method f charging a heatpump in the heating
mode?
a. | put the unit in cooling and charge by superheat | c. | charge to proper
sub-cooling | b. | weigh in an exact charge | d. | charge by superheat in heating mode |
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18.
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A continual roll-out on a gas furnace could be caused by
a. | a plugged heat exchanger | c. | excessive air
flow | b. | excess combustion air | d. | low air flow |
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19.
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What causes the liquid line defrost sensor on a heatpump to initiate a
defrost?
a. | a discharge temperature at the compressor over 150F | c. | increase in liquid line
temperature | b. | decrease in liquid line temperature | d. | constant, stable liquid line
temperature |
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20.
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Where should vibration eliminators be installed in a duct system?
a. | only on the supply | c. | after the first transition | b. | only on the return
| d. | between the air handler
and the first piece of duct |
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21.
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The fan limit control senses
a. | temperature rise across the furnace | c. | supply air
temperature | b. | return air temperature | d. | flue temperature |
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22.
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When should suction line filter/driers be installed?
a. | when non-condensable are in the system | c. | installing a new
system | b. | replacing a compressor following a burnout | d. | suction line pressure drop is below 5
PSIG |
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23.
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The component used to reduce liquid entering a compressor is called a:
a. | receiver | c. | filter/drier | b. | accumulator | d. | muffler |
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24.
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Most residences do not have mechanical fresh air intakes. Why?
a. | infiltration is used to meet fresh air needs | c. | most homes have fresh air
controls | b. | air cleaners are used to supply fresh air | d. | local codes prevent
it |
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25.
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Lifting flames in a natural draft gas furnace is most likely caused by:
a. | low manifold pressure | c. | to much secondary air | b. | excessive gas
pressure | d. | inadequate primary
air |
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26.
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Nominal manifold gas pressure on a natural gas, atmospheric draft furnace
is:
a. | 3"-4" wc | c. | 3psig - 4 psig | b. | 10"-12" wc | d. | 10psig to
12psig |
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27.
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The primary reason for sequencers on electric heat units is:
a. | increase inrush current | c. | ensure all elements are energized
at the same time | b. | lower inrush current | d. | prevent all elements from being energized at the same
time |
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28.
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An increase in latent load on the evaporator will most likely cause:
a. | no change in evaporator pressure but an increase in condenser pressure | c. | a increase in
evaporator and condenser pressure | b. | a decrease in evaporator and condenser
pressure | d. | an increase in
evaporator pressure and no change in condenser pressure |
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29.
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Nominal indoor airflow through a heatpump evaporator is:
a. | 200 CFM per ton | c. | 400 CFM per ton | b. | 300 CFM per ton | d. | 500 CFM per ton |
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30.
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An oil gun burner ignites the atomized oil by
a. | an ignition module | c. | ceramic hot surface | b. | a primary control | d. | electric arc between
electrodes |
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31.
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How would you best check to see if a fixed resistance crankcase heater is
working with power supplied ?
a. | a megohmmeter | c. | a volt meter | b. | an ammeter | d. | an ohmmeter |
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32.
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Which instrument(s) would you use to determine the total kilowatt output on an
unlabeled electric air handler?
a. | voltmeter & thermometer | c. | ohmmeter and
ammeter | b. | ohmmeter & voltmeter | d. | ammeter & voltmeter |
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33.
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Which of the following occurs when a heatpump defrosts?
a. | refrigerant cycle reverses to cooling, indoor fan stops and defrost relay
energizes | c. | defrost relay energizes, compressor stops, and supplemental heat
energizes | b. | compressor stops, supplemental heat energizes, and outdoor fan
stops | d. | refrigerant cycle
reverses to cooling, outdoor fan stops, and supplemental heat energizes if
available |
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34.
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On a new start-up of a heatpump, in the heating mode, the unit will not accept
the entire rated charge due to excessive discharge pressure. What is the most likely cause?
a. | improper refrigerant vapor line size | c. | insufficient air flow across the
outdoor coil | b. | improper liquid line size | d. | insufficient air flow across the indoor coil |
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35.
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A TXV equipped air-conditioner is experiencing low superheat, high suction
pressure and excessive compressor sweating. What is the most likely cause?
a. | power element lost its charge | c. | condenser coil is
dirty | b. | sensing bulb is loose | d. | undercharged |
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36.
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A four (4) burner gas furnace is experiencing low flame height on all of the
burners. What is most likely the problem?
a. | low manifold pressure | c. | oversized orifices | b. | flame impingement | d. | low primary air |
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37.
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On a call for heat. a spark-type ignition furnace experiences spark, pilot
lights, no further action. What is most likely happening?
a. | air switch did not close | c. | improper primary
air | b. | improper sequence of ignition | d. | inadequate flame
signal |
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38.
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The suction pressure of an R-410a system at the service valve is measured at 132
PSIG. The line temperature at the same point is 56F. What is the superheat?
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39.
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An R-22 air-conditioner is operating with a liquid line pressure of 211 PSIG and
liquid line temperature of 105F. What is the amount of sub-cooling?
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40.
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You find an iced over evaporator coil and the blower motor is hot and cycling on
and off. The problem is most likely:
a. | a faulty motor or capacitor | c. | capillary
restriction | b. | undercharge | d. | dirty condenser |
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41.
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On a call to a heatpump in the cooling mode, the compressor runs but the outdoor
fan does not. The fan motor and capacitor are determined to be okay. What is most likely?
a. | heat relay | c. | reversing valve | b. | contactor | d. | defrost control |
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42.
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A furnace with four heaters rated 5KW at 240 VAC is getting only 208 VAC. What
is the effect on the furnace?
a. | increase BTUH output | c. | no decrease if the heaters are connected in
parallel | b. | no decrease if the heaters are connected in series | d. | BTUH output will be
reduced |
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43.
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On start-up of a new heatpump, the unit heats satisfactorily but will not cool.
The likely cause is
a. | outdoor check valve not closing | c. | indoor check valve
open | b. | indoor check valve closed | d. | outdoor metering device is not metering |
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44.
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In the heating mode, which of the following would contain high pressure,
superheated vapor?
a. | suction line from reversing valve to compressor | c. | liquid line from indoor coil to
outdoor coil | b. | discharge line from compressor to reversing valve | d. | outdoor coil |
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45.
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In systems with TXV's on both indoor and outdoor coils, what purpose is
served by the check valves?
a. | bypass indoor TXV in heating and outdoor TXV in cooling | c. | bypass both outdoor
and indoor TXV's in cooling | b. | bypass outdoor TXV in heating and indoor TXV in
cooling | d. | bypass both outdoor
and indoor TXV's in heating |
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46.
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In the heating mode, liquid refrigerant can be found in:
a. | suction line from indoor coil to outdoor coil | c. | the reversing
valve | b. | the compressor | d. | liquid line from indoor coil to outdoor coil |
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47.
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A room to room load calculation is necessary to:
a. | determine supply and return grill locations | c. | air
distribution | b. | return air duct location | d. | velocity requirements |
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48.
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An often overlooked adjustment on new systems is:
a. | heat anticipator | c. | high limit switch | b. | air pressure switch | d. | return air
damper |
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49.
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Before connecting gauges to stem type (rotolok) service vales, what position
should the valves be before removing the caps?
a. | front seated and cracked | c. | back seated | b. | mid-seated | d. | completely front seated |
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50.
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An oversized air-conditioner could result in:
a. | high superheat | c. | high condenser pressure | b. | excessive
humidity | d. | increases
evaporator pressure |
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51.
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After new refrigerant piping has been installed and a leak check performed. the
system should be evacuated to:
a. | 30 inches | c. | 500 microns or less | b. | 29 inches | d. | 1000 to 1500
microns |
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52.
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On a service call to a new oil furnace, after resetting the primary control, the
unit ignites and runs for approximately 45 seconds then stops. What is the most likely
problem?
a. | dirty or faulty CAD cell | c. | wrong nozzle
size | b. | excessive oil pressure | d. | closed primary safety switch |
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53.
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The primary purpose for a lock-out on an ignition control is to prevent:
a. | excessive fuel build up | c. | burner short
cycling | b. | furnace overheating | d. | damage to the ignition control system |
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54.
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Which of the following is most important for proper vent operation?
a. | sufficient return air | c. | sufficient conditioned air | b. | adequate combustion
air | d. | adequate supply
air |
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55.
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An electronic air cleaner should be wired to operate:
a. | only when the humidifier is running | c. | constantly | b. | only when the
furnace blower is operating | d. | only on a call for heat |
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56.
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On a service call to a new oil furnace, you find the pump pressure to 50 PSIG.
What, if anything should yo do?
a. | increase the pump pressure | c. | reduce the pump
pressure | b. | add a new fuel filter | d. | no action needed |
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57.
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On a call to a straight cooling unit You find: head pressure above normal,
temperature rise across the coil is 42F and sub-cooling is 5F. What is the probable cause?
a. | dirty outdoor coil | c. | clogged liquid line drier | b. | clogged indoor air
filter | d. | refrigerant
overcharge |
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58.
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What is the purpose of a gas supply line drip leg?
a. | allows for the expansion of the gas | c. | drain condensation from the
evaporator coil | b. | remove condensation from the heat exchangers of high efficiency
furnaces | d. | prevent
contamination from entering the gas valve |
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59.
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When determining proper supply wire size, you must consider:
a. | voltage the unit is supplied with | c. | rating plate
ampacity | b. | minimum circuit ampacity and length of the wire | d. | rating plate current
only |
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60.
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Which of the following is a safety concern when positioning a gas
furnace?
a. | adequate gas supply | c. | clearance from combustible materials | b. | availability of a
flue within 2 feet | d. | distance
from the circuit breaker |
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61.
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Which of the following could cause evaporator flooding on a capillary tube
equipped system?
a. | low airflow through the evaporator | c. | excessive evaporator
airflow | b. | low outdoor ambient | d. | high indoor load |
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62.
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In the cooling mode of piston equipped heatpumps, the outdoor piston will be in
the:
a. | bypass position | c. | metering position | b. | front-seated position | d. | vertical
position |
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63.
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The indoor coil frosts on start up of a new air-conditioner. Which of the
following could be the cause?
a. | overcharge | c. | low indoor airflow | b. | restricted suction drier | d. | excessive indoor
airflow |
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64.
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On a call for cooling, with 230VAC supplied, T1 and L1 close, T2 and L2 do not
make contact. What voltage readings would you get?
a. | 230VAC between T1 & L1 | c. | 230VAC between L1 &
L2 | b. | 230VAC between T2 & L2 | d. | 230VAC between R & C |
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65.
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To determine proper heat anticipator settings, measure the current
a. | on the R wire | c. | on the C wire | b. | on the W wire | d. | on the G wire |
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66.
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When checking compressor motor windings, the ohmmeter should be set on what
scale?
a. | RX1 | c. | RX1K | b. | RX100 | d. | RX10K |
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67.
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To remove non-condensable, connect the vacuum pump to
a. | both high and low sides | c. | high side only | b. | low side
only | d. | suction
only |
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68.
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On start-up, a heatpump thermostat should be checked to see that
a. | first stage operates the compressor and second stage operates the reversing
valve | c. | first stage operates the airhandler and second stage operates the
compressor | b. | first stage operates the compressor and second stage operates the auxiliary
heat | d. | first and second stage
operate different stages of auxiliary heat |
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69.
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The most accurate method of controlling refrigerant flow over a wide range of
loads is to use
a. | a capillary tube | c. | use an automatic expansion valve | b. | use a thermostatic
expansion valve | d. | use a
metering orifice |
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70.
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Which of the following could cause high discharge pressure in a cooling
system?
a. | dirty condenser coil | c. | dirty evaporator coil | b. | low
charge | d. | liquid line
restriction |
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71.
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Manufacturer's requirements for venting "90+" furnaces include,
size of the vent, number of elbows, venting materials and
a. | distance to combustibles | c. | temperature
rise | b. | length of vent | d. | direction of air flow |
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72.
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The most important advantage of using higher silver content alloys when brazing
is that
a. | the joint is stronger | c. | the joint will not corrode | b. | less heat is
required | d. | flux is not
required |
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73.
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On a slit-system air-conditioner, increasing the evaporator airflow
a. | removes less humidity | c. | increases the temperature difference across the
coil | b. | causes frost to build up on the coil | d. | removes more
humidity |
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74.
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Step opening gas valves are valves that open
a. | at a partial rate, then change to full rate | c. | at full rate then change to a
partial rate | b. | and close at the same time intervals | d. | to one burner at a
time |
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75.
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Which of the following could indicate an overcharge on a fixed metering
air-conditioner?
a. | low head, low suction | c. | excessive superheat | b. | high head, high suction | d. | low
sub-cooling |
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76.
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What is the primary reason for a low ambient control?
a. | controls indoor blower during mild weather | c. | maintains minimum discharge
pressure | b. | shuts off the compressor when outdoor temperature rises above 35F | d. | switches condenser fan to high
speed |
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77.
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Which of the following are needed to determine superheat?
a. | discharge line temperature and suction line temperature | c. | liquid pressure and
temperature | b. | air temperature difference across evaporator | d. | suction pressure and
temperature |
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78.
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On a service call to an oil furnace, what safety precaution should the
technician make before firing the furnace?
a. | disconnect electricity | c. | check oil pressure | b. | check for grounded
electrodes | d. | check for liquid
oil in the combustion chamber |
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79.
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Which of the following are needed to check oil furnace efficiency?
a. | net stack temperature and CO2 concentration | c. | net stack and indoor
temperature | b. | net stack temperature and CO | d. | stack temperature and fuel
pressure |
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80.
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When using hard drawn tubing, which of the following should be used to fabricate
a 90 bend?
a. | a 90 flared union | c. | a spring bender | b. | a 90 compression elbow | d. | a long radius 90
elbow |
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81.
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What is the maximum fill level for a refrigerant recovery cylinder?
a. | 50% of name plate capacity | c. | 70% of rated
capacity | b. | 60% of name plate | d. | 80% of rated capacity |
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82.
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If the pressure switch on an induced draft furnace fails to close, the most
likely cause is
a. | a blockage in the vent system | c. | manifold pressure too
low | b. | circulating blower is on the wrong speed | d. | manifold pressure too
high |
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83.
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To energize the electric strips in a heatpump the technician may need to
a. | check the anticipator current | c. | jumper or adjust outdoor
thermostats | b. | turn thermostat all of the way down | d. | check auxiliary heat light on
thermostat |
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84.
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Lower than normal voltage at the compressor contactor coil can be caused
by
a. | thermostat wire too small | c. | higher that normal supply
voltage | b. | oversized control transformer | d. | incorrect
capacitor |
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85.
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When check flame current, the meter should be set for
a. | AC milliamps | c. | AC microamps | b. | DC milliamps | d. | DC microamps |
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86.
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The common terminal on heatpump thermostats is used for
a. | power the outdoor thermostats | c. | stabilize the voltage in the
cooling cycle | b. | power shunt type anticipator and indicator lights | d. | add power to the back-up
heaters |
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87.
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The vent safety switch installed in the draft hood area
a. | protects the furnace from overheating if the limit fails | c. | shuts down the gas
valve if the furnace is spilling vent products | b. | automatically increases blower speed if the
furnace overheats | d. | protects
the heat exchanger from damage |
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88.
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For safety, when checking an electric furnace, after turning off the unit
disconnect you should check
a. | ohms from L1 to ground | c. | resistance of the sequencers | b. | voltage on the line
side of the disconnect | d. | voltage on the load side of the disconnect |
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89.
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Velocity in a 12" X 12" duct is measured at 800 FM.hat is the air
volume?
a. | 144 CFM | c. | 800 CFM | b. | 400 CFM | d. | 1600 CFM |
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90.
|
Refrigerants can become toxic when they contact
a. | contaminated oil | c. | a high heat source | b. | water or moisture | d. | nitrogen |
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91.
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Velocity pressure is static pressure minus total pressure
a. | total pressure minus static pressure | c. | static pressure plus total
pressure | b. | static pressure minus differential pressure | d. | static pressure times duct cross sectional
area |
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92.
|
Manifold gas pressure on a single stage propane system should normally be
a. | 3.5" wc | c. | 10" wc | b. | 7" wc | d. | 13" wc |
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93.
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Which of the following is not an accepted method of leak detection?
a. | R-22 and compressed air | c. | R-22 and
nitrogen | b. | R-22 and an inert gas | d. | nitrogen only |
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94.
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The purpose of the National Fuel Gas Code is to
a. | provide a material list for a gas installation | c. | provide minimum safety requirements
for a gas appliance/installation | b. | identify the number of safety devices needed in
a gas installation | d. | satisfy
the local building code |
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95.
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What happens to static pressure after sealing a leaky duct system?
a. | increases | c. | changes to total pressure | b. | decreases | d. | changes to velocity pressure |
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96.
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What instrument is used to measure duct velocity
a. | pyrometer | c. | hygrometer | b. | anemometer | d. | tachometer |
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97.
|
What is the biggest disadvantage of using flex duct as compared to sheetmetal
duct?
a. | less pressure drop | c. | more restriction | b. | more fittings required | d. | increased installation
time |
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98.
|
Partially restricting the return side of a duct system will cause the amperage
of a PSC blower to
a. | decrease | c. | increase | b. | stay the same | d. | hunt up and
down |
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99.
|
What is the biggest safety hazard when using A1 refrigerants
a. | they are poisonous | c. | they are lighter than air | b. | suffocation | d. | they ignite in air |
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100.
|
A refrigerant cylinder weighs 36 lbs. The cylinder alone weighs 6 lbs. A
technician uses 1/6 of the refrigerant on one unit. He then uses 10 lbs on another job. How much
refrigerant is left in the cylinder?
a. | 14 lbs | c. | 16 lbs | b. | 15 lbs | d. | 20 lbs |
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