General Air

General Air-Conditioning

Multiple ChoiceIdentify the letter of the choice that best completes the statement or answers the question.

1. If an R-12 refrigeration system has its air-cooled condensing unit on a 100°F roof and the condenser outlet temperature (refrigerant) is 115°F, with how much subcooling is the condenser operating?a. 30°Fb. 15°Fc. 100°Fd. 130°F

ANSWER: BPOINTS: 0 / 1FEEDBACK:

2. During the defrost cycle of a forced draft low temperature evaporator, the evaporator fan would ____.a. remain on to speed up the defrostb. turn offc. cycle with the condenserd. cycle with the compressor


3. A Bourdon tube is often found in a ____.a. mercury barometerb. aneroid barometerc. pressure gauged. mercury thermometer

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4. Which type of refrigerant has the highest Ozone Depletion Potential (ODP)?a. HFCb. HCFCc. CFCd. All have the same ODP.


5. What happens when room temperature water is poured into a glass of ice?a. The ice gets colder.b. The ice melts because it is giving up the "cold" to the waterc. The ice melts because it is absorbing heat from the waterd. The ice melts because the water is colder than the ice.


6. How many chlorine atoms does it take to destroy 100,000 ozone molecules in the stratosphere?a. 10b. 1c. 100d. 10,000


7. The temperature of the compressed gas leaving the compressor can best be described as ____.a. coldb. coolc. warmd. very warm

ANSWER: DPOINTS: 0 / 1FEEDBACK:

8. When a refrigerant enters the compressor, it is a ____ and when it leaves the compressor, it is a ____.a. low pressure low temperature superheated vapor, high pressure high

temperature superheated vaporb. low pressure low temperature superheated vapor, low pressure low

temperature subcooled vaporc. high pressure superheated vapor, low pressure superheated vapord. low pressure low temperature subcooled liquid, high pressure high

temperature superheated vapor

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9. The compressor in a refrigeration system ____.a. raises the boiling point of the refrigerantb. pumps the refrigerant throughout the systemc. both a and bd. none of the above


10. An ampere is ____.a. the difference in potential between two chargesb. a measure of the quantity of electrons flowing past a point in the

electrical circuit in a given timec. the unit of measure for resistanced. the unit of measure for capacitance


11. The best method of leak checking is when the refrigeration system is ____.a. in a vacuumb. open to the atmospherec. operating with all fans activatedd. standing with dry nitrogen pressure of 150 psig in the system


12. If two light bulbs are wired in series and one bulb burns out, the other bulb will ____.a. go outb. stay onc. stay on, but it will be dimmerd. stay on, but it will be brighter


13. When the load on the evaporator increases, the TX valve ____.a. increases the flow of refrigerantb. decreases the flow of refrigerantc. maintains constant head pressured. decreases the pressure drop across the evaporator


14. A solid material exerts a pressure or force ____.a. in all directionsb. downward onlyc. outward and downwardd. outward only


15. The compressor motor and condenser fan motor are wired in ____.a. parallelb. seriesc. parallel/seriesd. with minimum wire length


16. If the compression ratio of a system with a reciprocating compressor decreases, the amount of refrigerant pumped by the compressor ____.a. will increaseb. will decreasec. will remain the samed. cannot be determined


17. Which of the following condensers is the most efficient?a. forced draft air-cooledb. induced draft air-cooledc. water-cooled parallel flowd. water-cooled counter flow


18. The dew-point temperature is the ____.a. temperature when the air is saturated with moistureb. temperature when the moisture begins to condense out of the airc. difference between the dry-bulb and wet-bulb temperaturesd. temperature of the air at 50% relative humidity


19. The water circuit in shell and coil and coil-type tube-in-a-tube condensers must be cleaned ____.a. by removing the end capsb. with a brushc. chemicallyd. by air pressure


20. The generalized comfort chart can be used as a basis to ____.a. determine combinations of temperature and humidity to produce

comfort in summer and winterb. study air and its propertiesc. determine the amount of fresh air make up necessary for comfortd. none of the above


21. Moisture in a liquid state must be ____ before it can be removed with a vacuum pump.a. vaporizedb. condensedc. cooledd. solidified

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22. A vapor material exerts a pressure or force ____.a. in all directionsb. downward onlyc. outward and downwardd. outward only


23. When charging a refrigeration system with a near-azeotropic mixture, what must be done to prevent liquid from entering the system?a. Charge only as a vapor through the high side.b. Charge only liquid through the high side.c. Charge as a liquid through the low side using a restrictor.d. Charge as a vapor through the low side using a resistor.


24. What effect is ozone depletion having on the environment?a. increased ground level ozone (smog)b. reduced marine lifec. reduced crop fieldsd. all of the above


25. A normally operating water-cooled condenser is operating with a 10° differential between water in and water out. If the amount of 85°F water going through the condenser is reduced, which of the following is a possible temperature of the water leaving the condenser?a. 75°Fb. 0°Fc. 95°Fd. 105°F


26. Of the following choices, the warmest temperature is ____a. 20°Cb. 303°Kc. 501°Rd. 77°F


27. How many Btus must be removed from one pound of water at 200°F for it to end up as ice at 30°F?a. 144 Btub. 828 Btuc. 313 Btud. 526 Btu


28. The Fahrenheit absolute scale is calleda. Celsius c. kelvinb. centigrade d. Rankine


29. What is the relative humidity if the dry-bulb temperature is 100 º F and the wet-bulb temperature is 65°F?a. 33%b. 63%c. 43%d. 13%


30. The pressure in a refrigeration system is changed in the ____.a. condenser and compressorb. compressor and expansion devicec. expansion device and evaporatord. condenser and evaporator


31. A helicopter is lifting an 800-pound unit at a rate of 200 feet per minute. How many horsepower of work energy is the helicopter using in the process?a. 3.863 hpb. 4.517 hpc. 4.848 hpd. 5.209 hp


32. Rotary compressors are used primarily in ____.a. large industrial refrigeration and air conditioning systemsb. residential air conditioningc. small commercial refrigeration unitsd. domestic refrigerators


33. A homeowner plans to build a house out in Las Vegas, Nevada, in the middle of the desert. It would be in his/her best interest to lower the "solar load," to locate most of the windows on the ____.a. north and east sides of the houseb. east and west sides of the housec. north and south sides of the housed. south and west sides of the house


34. The ozone depletion factor of R-12 is ____.a. 0.8b. 0.016c. 0.05d. 1.0

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35. If 30 oz. of refrigerant are to be added to a refrigeration system and the supply cylinder weighs 26 lb. 4 oz. before any is added, what will the supply cylinder weigh after the system has been charged?a. 22 lb. 8 oz.b. 24 lb. 6 oz.c. 24 lb. 8 oz.d. 22 lb. 4 oz.


36. The shell and tube condenser is cleaned ____.a. with a brush after removing the end capsb. only with chemicalsc. with compressed aird. with a vacuum cleaner


37. A liquid material exerts a pressure or force ____.a. in all directionsb. downward onlyc. outward and downwardd. outward only


38. High efficiency condensers ____.a. can withstand higher pressures than standard condensersb. have more surface area than standard condensersc. have stainless steel coilsd. are located in separate cabinets


39. PSIA at sea level (under standard conditions) is approximatelya. 0 PSI c. 14.696 PSI

b. 29.92 PSI d. None of the above


40. To remove the refrigerant from a system without any testing or processing and to be put back into the same system is called ____.a. recoveryb. renewc. reclaimd. recycle


41. If reservoir-type humidifiers are not properly maintained, which of the following can be discharged into the air?a. fungib. bacteriac. algaed. all of the above


42. The TXV sensing bulb is mounted ____.a. on the liquid line between the condenser and the TX valveb. at the inlet to the condenserc. on the suction line between the evaporator and the compressord. on the compressor discharge line


43. The pressure limiting TX valve ____.a. allows the compressor to operate at low condenser entering air

temperaturesb. shuts off the condenser fan during hot pull downc. maintains the full refrigerant flow rate during a hot pull downd. limits the refrigerant flow rate to the compressor capacity

ANSWER: D

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44. When a system with a water-cooled condenser cycles off, the water regulating valve should ____.a. remain open during the off cycleb. close, since the head pressure is lowerc. open all the way to remove any residual heatd. re-calibrate itself to maintain the new lower head pressure


45. The screw-type compressor is used primarily in ____.a. large industrial refrigeration and air-conditioning systemsb. residential air conditioningc. small commercial refrigeration unitsd. domestic refrigerators


46. An extended surface filter (pleated type) ____.a. does not clog up as quickly as a standard filterb. is able to remove more dirt since the surface area is largerc. costs less than a standard filterd. both a and b


47. Which of the following can be used to maintain the head pressure of a system with an air-cooled condenser?a. fan cyclingb. condenser flooding valvec. dampers or louversd. all of the above


48. If the wet-bulb and dry-bulb temperature are both 80°F, what is the

humidity?a. 0%b. 50%c. 75%d. 100%


49. A ton of refrigeration is equal to ____.a. 1 ton of iceb. 288000 Btu/24-hr.c. 144 Btu/hr.d. 12000 Btu/min.


50. If the dry-bulb temperature is 93°F and the wet-bulb temperature is 60°F, what is the specific volume of the air?a. 14.0 ft3/lbb. 14.0 lb/ft3

c. 10 lb/ft3

d. 10 ft3/lb


51. When charging liquid refrigerant from a single valve supply cylinder, the cylinder is placed ____.a. upside downb. right side upc. on its side


52. The air temperature of the air off an evaporative cooler is ____.a. warmer than the entering airb. cooler than the entering airc. the same as the entering aird. made up of sensible heat only


53. In rotary type motor-compressor assemblies, the motor is cooled by ____.a. air over the shell of the assemblyb. discharge gas from the compressorc. suction gas returning to the compressord. liquid refrigerant by-passed from the liquid line


54. A multiple evacuation means that ____.a. you connect three vacuum pumps simultaneously to a refrigeration

system and pull a vacuumb. you pull a vacuum on three different systems at the same timec. you pull a vacuum on a refrigeration system more than once,

allowing refrigerant or nitrogen into the system between each procedure

d. there must be more than one system operating before a vacuum can be pulled


55. At a constant pressure, the volume of a gas varies as to the absolute temperature and at a constant volume the pressure of the gas varies directly with the absolute temperature. This is known as ____.a. Charles' Lawb. Tom's Lawc. Boyle's Lawd. Dalton's Law


56. The wet-bulb temperature ____.a. is the same as the wet-bulb depressionb. is the saturation pressurec. takes into account the moisture content of the aird. is always higher than the dry-bulb temperature


57. A house is built on property whose soil is rich in uranium. The occupants of the house may ____.a. be exposed to radon gasb. be more susceptible to lung cancerc. smell the pungent odor of the radond. both a and b


58. On a split air conditioning system with a remote condenser, which refrigerant lines must be field installed?a. discharge and suctionb. liquid and suctionc. discharge and liquidd. No lines need to be installed.


59. To find the watts of electrical power in an electrical circuit, you multiply ____.a. ohms and amperesb. ohms and voltsc. volts and amperesd. volts, amperes, and ohms


60. What can be used to maintain the head pressure of a system with a water-cooled condenser?a. fan cyclingb. dampers or louversc. water regulating valved. all of the above

ANSWER: C

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61. A forced draft high temperature evaporator would ____.a. have its fins very close togetherb. not need to be defrostedc. need a hot gas defrostd. both a and b


62. Which of the following terminal combinations would show an open circuit if the internal overload device in a hermetic compressor should open due to excessive heat?a. common to startb. common to runc. start to rund. both a and b


63. Balanced port TX valves are used to ____.a. feed refrigerant at a normal rate with low condenser entering air

temperaturesb. feed refrigerant at a normal rate with high condenser entering air

temperaturesc. stop refrigerant flow with high condenser entering air temperaturesd. stop refrigerant flow with low condenser entering air temperatures


64. A dirty condenser coil can lead to ____.a. increased efficiencyb. reduced efficiencyc. increased head pressured. both b and c


65. Ice melts in icechests or coolers because ____.a. Heat flows through the insulated walls.b. Heat enters when the door is openedc. Heat enters when warm food is placed in the chest.d. All of the above


66. If a low temperature evaporator is forming ice, which of the following is a possible problem?a. evaporator fan not runningb. compressor not runningc. condenser fan not runningd. no problem, ice formation normal


67. The total pressure of a confined mixture of gases is the sum of the pressures of each of the gases in the mixture. This is known as ____.a. Charles' Lawb. Tom's Lawc. Boyle's Lawd. Dalton's Law


68. Which of the following refrigerants is considered an HFC-type of refrigerant?a. R-134ab. R-12c. R-22d. R-11


69. Technician "A" says that if the air filter on an air-conditioning system is totally blocked with dirt, the amperage draw of the evaporator fan motor

will go down. Technician "B" says that if you close down one supply register on a duct system, the volume of air feeding the other locations will increase slightly. Which of the following statements is correct?a. Technician "A" is correct. Technician "B" is correct.b. Technician "A" is correct. Technician "B" is incorrect.c. Technician "A" is incorrect. Technician "B" is correct.d. Technician "A" is incorrect. Technician "B" is incorrect.


70. Condensing temperatures in an air-cooled condensing unit can be reduced by ____.a. increasing the condensing surface areab. increasing the cfm through the condenserc. decreasing the temperature of the air entering the condenserd. all of the above


71. Under what conditions would a package air-conditioning system need to be charged?a. during initial installationb. during compressor replacementc. after the suction line crackedd. both b and c


72. Comfort can be described as the gentle balance between ____.a. air cleanliness, air movement, temperature, and humidityb. air velocity, air cleanliness, humidity, and air movementc. air speed, air velocity, temperature, and humidityd. acceleration, air cleanliness, filtration, and humidity


73. A refrigeration system is operating with a vapor charged thermostatic expansion valve. The thermal bulb is sensing a suction line temperature

that is higher than the temperature that allows liquid to be present in the bulb. Any additional increases in the evaporator load will ____.a. increase the bulb pressure and cause the thermostatic expansion

valve to openb. increase the evaporator pressure and cause the thermostatic

expansion valve to closec. decrease the spring pressure and cause the thermostatic expansion

valve to opend. have no effect on the position of the needle (pin) in the seat


74. What are the relative humidity limits recommended for residences?a. 20% to 40%b. 30% to 50%c. 40% to 60%d. 50% to 70%


75. The heat required for off-cycle defrost is obtained from ____.a. supplemental electric heat when the system is shut downb. hot gas when the system is operatingc. the space temperature when the compressor is offd. hot liquid from the compressor


76. The human body gives off heat by which of the following?a. convectionb. radiationc. conductiond. all of the above


77. A typical evaporator operating temperature in an air-conditioning system is ____.

a. 40°Fb. 55°Fc. 75°Fd. 200°F


78. In reciprocating and scroll type motor-compressor assemblies, the motor is cooled by ____.a. air over the shell of the assemblyb. discharge gas from the compressorc. suction gas returning to the compressord. liquid refrigerant by-passed from the liquid line


79. A compound gauge ____.a. indicates pressures above 14.696 psiab. indicates pressures in inches Hg below atmospheric pressurec. is one of two gauges on a typical gauge manifoldd. all of the above


80. The factory charge in a split system, using R-22, shows 6 lb. 8 oz. in the outdoor condensing unit and 2 oz. in the evaporator. The 3/8" liquid line contains 0.48 oz. per foot and the 7/8" suction line contains 0.10 oz. per foot. The refrigerant lines are 30' long. What is the correct refrigerant charge for this system?a. 6 lb. 10 oz.b. 6 lb. 15 oz.c. 7 lb. 7 oz.d. 7 lb. 11 oz.


81. Which of the following would allow a system to operate more efficiently?a. condenser that had refrigerant leaving with 10° of subcooling

b. condenser that had refrigerant leaving with 15° of subcoolingc. condenser that had refrigerant leaving as 100% vapord. condenser that had refrigerant leaving with 10°F of superheat


82. Control of the head pressure in an air-cooled condenser is done by ____.a. cycling the condenser fanb. controlling dampers in the airstream through the condenserc. flooding the condenser with refrigerantd. all of the above


83. The primary function of an expansion device is to ____.a. produce a reduction in the pressure on the liquid refrigerantb. regulate the flow of refrigerant into the evaporatorc. lower the boiling point of the refrigerant far enough below the

temperature of the load to get the needed heat transfer rated. all of the above


84. High temperature refrigeration is that produced by ____.a. heat from a furnaceb. an air-conditioning systemc. the vegetable cooling system of a refrigeratord. the freezer section of a refrigerator


85. The reason for using a reducing extended plenum system is to ____,a. save metal by using a smaller ductb. reduce the operating cost of the systemc. provide easier means of fastening the take off fittingsd. maintain a more even pressure throughout the entire length of the

trunk duct


86. Which of the following is an example of an HCFC refrigerant?a. R-12b. R-402c. R-22d. R-134a


87. A normally operating water-cooled condenser is operating with a 10° differential between water in and water out. If scale forms on the water tubes and the entering water is 85°F, which of the following is possible?a. The outlet water will be 88°F.b. The system head pressure will rise.c. The water regulating valve will close.d. Both a and b are correct.


88. One watt of electrical energy is equal to ____.a. 3.1416 Btub. 3.413 Btuc. 3.3416 Btud. 3.3146 Btu


89. The condenser in a refrigeration system ____.a. desuperheats the vapor from the compressorb. condenses the vapor from the compressorc. subcools the liquid refrigerant before it leaves the condenserd. all of the above


90. As loads are added in a parallel circuit, the total resistance of the circuit ____.a. will increaseb. will decreasec. will remain the samed. cannot be determined


91. A micron gauge is used to measure ____.a. atmospheric pressures at high altitudesb. atmospheric pressures at sea levelc. absolute pressures below 1 mm Hgd. high pressure in a refrigeration system


92. If a thermostatic expansion valve's thermal bulb came loose from the suction line at the outlet of the evaporator, which of the following could result?a. The bulb pressure would increase and the thermostatic expansion

valve would open.b. The superheat in the evaporator would decrease.c. Liquid refrigerant would flow back to the compressor.d. All of the above are correct.


93. The controller for a humidifier, a humidistat, has a power element that is ____ sensitive.a. moistureb. lightc. infraredd. temperature


94. To reprocess refrigerant to meet new product specifications is called ____.

a. recoveryb. renewc. reclaimd. recycle


95. Standard atmospheric pressure at sea level is ____.a. 29.60" Hgb. 29.71" Hgc. 29.83" Hgd. 29.92" Hg


96. If five electrons combine with three protons, the net charge will be ____.a. negativeb. positivec. zerod. neutral


97. If the temperature remains constant and the volume that a gas occupies increases, the pressure will ____.a. decreaseb. increasec. remain the samed. cannot be determined from the information given


98. The purpose of an externally equalized thermostatic expansion valve is to ____.a. compensate for excessive evaporator pressure dropb. allow system to equalize fasterc. prevent the expansion valve from frosting upd. allow refrigerant to expand in the compressor


99. When exposed to salt air, the material combination used in air conditioning evaporators and condensers may be ____.a. copper tube-stainless steel finb. copper tube-copper finc. copper tube-aluminum find. aluminum tube-aluminum fin


100. If a high temperature evaporator is forming ice, which of the following is a possible problem?a. evaporator fan not runningb. compressor not runningc. condenser fan not runningd. no problem, ice formation normal


101. The two (2) most common substances used in liquid column thermometers area. water & oil c. oil & mercuryb. mercury & alcohol d. alcohol & oil


102. The heat in a vapor above its saturation point for that pressure is calleda. sensible c. specificb. latent d. superheat


103. The dry-bulb temperature is the ____.a. same as the wet-bulb temperature

b. total of the sensible and latent heatc. sensible heat level of the aird. sensible heat less the humidity


104. The fitting at the end of a round duct that connects the duct to the floor register is called a(n) ____.a. end bootb. reducerc. take offd. stack head


105. To clean refrigerant by the use of filter dryers is called ____.a. recoveryb. renewc. reclaimd. recycle


106. The discus valve design is more efficient than a flapper valve design because ____.a. it allows a compressor design with less clearance volumeb. it operates with less spring tensionc. the amount of expanded vapor in the cylinder is greaterd. it will not allow liquid refrigerant in the cylinder


107. The refrigerant in a condenser in a refrigeration system ____.a. absorbs heatb. gives up heatc. changes to a vapord. is under lower pressure than the evaporator


108. If a conductor carrying electrical current is formed into a coil, the magnetic field around the wire will ____.a. cancel outb. increasec. decreased. remain the same


109. What happens to the current in a circuit if the resistance is increased?a. The current remains the same.b. The current increases.c. The current decreases.


110. The Celsius absolute scale is calleda. Fahrenheit c. kelvinb. centigrade d. Rankine


111. Which of the following refrigerants has the lowest boiling temperatures at atmospheric pressure?a. R-12b. R-22c. R-134ad. R-502


112. More than one evaporator coil circuit is used when ____.a. the evaporator is located outside the conditioned areab. there would be excessive refrigerant pressure drop in the coil circuit

c. a distributor would not be practicald. a slant coil is at an angle more than 60°


113. If the suction valve in a reciprocating compressor is leaking slightly, the ____.a. cooling capacity will be reducedb. flow rate of refrigerant through the system will increasec. compressor can overheatd. both a and c


114. Most of the heat energy in the suction vapor entering the compressor is ____.a. heat of compressionb. sensible heatc. latent heatd. defrost heat


115. What is the recommended maximum number of grains per pound of material in the water supplied to an atomizing humidifier?a. 10b. 50c. 100d. 125


116. A refrigeration system designed for the storage of flowers or candy is considered a ____ type.a. high temperatureb. medium temperaturec. low temperatured. sharp freezing


117. Which of the following is typically measured with an inclined water manometer?a. static pressure in a duct systemb. pressure in a refrigeration systemc. manifold pressure in a gas fired furnaced. nozzle pressure of an oil burner


118. Atomizing humidifiers discharge ____ into the air.a. CO2

b. electronic ionsc. tri-valant oxygend. tiny water droplets


119. Refrigerant in vapor form is normally put into the system through the ____.a. liquid lineb. suction linec. hot gas lined. liquid return line


120. If a low temperature evaporator is forming excess ice, which of the following could be a possible problem?a. The evaporator fan motor is defective.b. The unit is not staying in defrost long enough.c. The defrost heater is defective.d. All of the above are correct.


121. What is the dew-point temperature if the wet-bulb temperature is 65°F and the dry-bulb temperature is 100°F?a. 40°Fb. 50°Fc. 60°Fd. 70°F


122. The purpose of a capillary tube is to ____.a. regulate the refrigerant flow into the evaporatorb. lower the pressure of the liquid refrigerantc. lower the boiling point of the refrigerantd. all of the above


123. If an evaporator has a pressure drop of 10 psig and the low side pressure is 15 psig, what is the pressure at the inlet of the evaporator?a. 10 psigb. 25 psigc. 15 psigd. 5 psig


124. What is the most accurate instrument for checking a deep vacuum?a. compound gaugeb. mercury "U" tube manometerc. mercury barometerd. electronic vacuum gauge


125. To insure accurate testing, the best material to use for connecting lines to the vacuum pump and gauge set is ____.a. light flexible hose

b. heavy duty rubber gauge linec. copper tubed. garden hose


126. Temperature is an indication of the ____.a. amount of heat in a materialb. density of the materialc. amount of molecular activity in the materiald. weight of the total mass of the material


127. Which of the following represents a different temperature than the other three?a. 15°Cb. 59°Fc. 475°Kd. 519°R


128. How many Btus are required to change one pound of ice at 20°F to steam at 220°F?a. 1,304 Btu/hb. 2,608 Btu/hc. 6,520 Btu/hd. 3,912 Btu/h


129. If the thermal bulb assembly develops a leak, what will occur?a. All of the system's refrigerant will leak out.b. The bulb pressure will reduce and the valve will close.c. The valve will open to allow more refrigerant to flow.d. It will have no effect on system operation.


130. Heat that changes the state of a substance is calleda. calorie c. sensibleb. BTU d. latent


131. Electronic air cleaners generally have ____.a. ionizing sectionsb. charcoal filtersc. pre-filtersd. all of the above


132. Refrigerants that are made up of two refrigerants that, when blended in the right proportions, combine to make a third stable refrigerant, are called ____.a. blendsb. azeotropesc. near azeotropesd. mixtures


133. The wet-bulb depression is ____.a. the difference between the dry-bulb and wet-bulb temperaturesb. the same as the wet-bulb temperaturesc. the same as the dry-bulb temperaturesd. when the air is saturated with moisture


134. The cross liquid charge bulb at the TXV contains fluid that ____.a. has similar characteristics to the system fluid to prevent liquid

refrigerant from entering the suction lineb. has different characteristics from the system fluidc. causes the valve to stay open during the off cycled. follows the typical pressure-temperature relationship


135. Mineral deposits in the water portion of a water-cooled condenser act as ____.a. a conductor of heatb. an insulatorc. a cleaning solutiond. They have no effect on the operation of the condenser.


136. If the resistance against a propeller fan is doubled, the cfm output decreases, but the amperage draw of the motor ____.a. decreasesb. increasesc. stays the samed. overheats the motor


137. At standard conditions on the Celsius scale, water will boil at ____.a. 100°Cb. 212°Cc. 32°Cd. 0°C


138. How many Btu's are required to change five pounds of ice at 20°F to steam at 220°F?a. 1,304 Btu/hb. 2,608 Btu/hc. 6,520 Btu/h

d. 3,912 Btu/h


139. An air-cooled condenser that is operating in a climate that has four distinct seasons must ____.a. have some type of head pressure controlb. use a water regulating valvec. have a multi-circuit evaporatord. operate with zero degrees of subcooling


140. Noncondensable gases ____.a. are desirable in a refrigeration systemb. are undesirable in a refrigeration systemc. condense readily under normal atmospheric conditionsd. help in pulling a vacuum


141. One of the most common substances that is used as an absorber is ____.a. charcoalb. silica gelc. fiberglassd. foam rubber


142. PSIG indicates ____.a. pounds per square inch absolute gravityb. pounds per square inch gagec. pounds per square inch of pressure absoluted. pounds per square inch of gravity


143. The steps to aggressively controlling the contamination of indoor air would involve ____.a. locating and eliminating the source of contaminationb. providing adequate ventilationc. providing methods for cleaning the aird. all of the above


144. The temperature on the Celsius scale where all molecular activity stops is approximately ____.a. -273°Cb. -272.6°Cc. -277.8°Fd. -274.1°C


145. The density of air is the ____.a. amount of moisture in the airb. amount of movement in the air per cubic footc. weight of the air per cubic footd. combination of the temperature and pressure of the air


146. To pull a vacuum means to ____.a. raise the pressure in a refrigeration systemb. lower the pressure in a refrigeration system below atmosphericc. allow refrigerant to escape into the atmosphered. condense the gas in the system


147. The capacity of an evaporator is affected by ____.a. the saturation pressure of the low side of the systemb. the saturation pressure of the high side of the system

c. the amount of evaporator superheatd. all of the above


148. Liquid entering the compression chamber of a reciprocating compressor can lead to ____.a. damaged valvesb. damaged piston ringsc. damaged expansion valvesd. both a and b


149. Measuring velocity pressure in a duct indicates the ____.a. volume of air through a ductb. speed at which the air is movingc. pressure against the sides of the ductd. weight of the air moving through the duct


150. The unit used to measure electrical power is the ____.a. voltb. amperec. wattd. ohm

ANSWER: C

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