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Retired questions · Refrigeration AC - USCG Exam Questions

These are retired questions the Coast Guard no longer draws exams from. They stay online for reference; the current questions are in Refrigeration AC.

Refrigeration cycles and components, compressors, refrigerants, and marine air conditioning systems.

Every question below is a real U.S. Coast Guard exam question with four choices. Answer one and the correct choice is revealed instantly, with the USCG reference and illustration where the question uses one.

Random question Start at question 8 Build a timed exam

All Retired questions · Refrigeration AC questions

Questions 1–100 of 134 · page 1 of 2

  1. #8 If you mistakenly change from a lower pour point lubricant to a higher pour point lubricant in a refrigeration system, what will be the result?
  2. #9 Properties of a good refrigeration compressor lubricating oil include which of the following?
  3. #14 Regarding heat transfer principles, which of the following is true?
  4. #22 Which pair of the illustrated service gauge manifold sets would require switching hoses when transitioning from a dehydration evacuation to refrigeran... illustration
  5. #23 With a service gauge manifold set connected to a refrigerant compressor as shown in the illustration, which arrangement of the gauge manifold set valv... illustration
  6. #24 In a refrigeration system, once the gage manifold hoses are attached to the compressor service valve connections and properly purged, what should be t...
  7. #25 When purging a refrigeration gage manifold using system pressure as the source of refrigerant for purging, which of the fittings listed is normally ti...
  8. #32 Which of the illustrated valves is used to gain access to a hermetic system and features a Schrader core valve which is unseated by the core depressor... illustration
  9. #40 Using the device shown in the illustration, which of the following statements is true when adding refrigerant as a vapor to the low side of the refrig... illustration
  10. #41 After the refrigerant has been recovered, leaks repaired if necessary, the system ideally should undergo a dehydration evacuation prior to recharging... illustration
  11. #44 What must be done, at a minimum, before a system can legally be opened up for repairs while adhering to the prohibition against the venting of halogen...
  12. #45 The process of removing refrigerant from a system and storing it without testing or processing it in any way is known as what under the EPA Clean Air...
  13. #53 As shown in the illustrated flow diagram for a self-contained recovery unit designed for the recovery of refrigerants from high pressure appliances as... illustration
  14. #54 Concerning frost appearing on one set of evaporator coils of a multi-box, direct expansion type refrigeration system, what is true?
  15. #66 Of the various possible methods shown in the illustration, which is the correct method of attaching a TXV feeler bulb to a small large line (7/8" and... illustration
  16. #86 Which of the following conditions will occur if the power element of the thermostatic expansion valve shown in the illustration loses its charge? GS-R... illustration
  17. #93 You are checking the supply chilled water temperature thermistor probe on a high- pressure hermetic centrifugal chiller. Using the illustrated chart,... illustration
  18. #95 Some refrigeration systems have chemical moisture indicators installed in conjunction with the sight glass in the liquid line. If excess moisture is p...
  19. #96 If a liquid drying agent is used in a refrigeration system already equipped with a solid drying agent, the liquid drying agent will cause what type of...
  20. #102 The fluid used as a source of actuating power against the underside of the unloader power element piston of the refrigeration compressor capacity cont... illustration
  21. #103 During operating periods of a multi-box refrigeration system using a capacity controlled compressor, when all of the evaporators of a four box plant a... illustration
  22. #108 A box solenoid valve used in a multi-box refrigeration system is operated by electro- magnetic action by what control device?
  23. #112 As shown in the illustrated refrigeration system piping schematic diagram with the various accessories and controls and equipped with an air-cooled co... illustration
  24. #114 If it is necessary to increase the operating head pressure of the refrigeration system using the device shown in the illustration, what should be done... illustration
  25. #115 In a refrigeration system, the valve shown in the illustration is used for what purpose? GS-RA-14 illustration
  26. #116 The set point adjustment of the device shown in the illustration is made by rotating what component? GS-RA-14 illustration
  27. #118 Through which of the components shown in the illustration is flash gas formation a normal occurrence? GS-RA-25 illustration
  28. #119 In the multi-evaporator refrigeration system shown in the illustration, what is the proper name for the valve labeled "29"? GS-RA-12 illustration
  29. #125 In addition to the indicated gauge pressure, what other information is presented on the compound gauge for the hypothetical refrigerant illustrated? G... illustration
  30. #126 Which lettered component, shown in the illustration, indicates the location of the receiver? GS-RA-12 illustration
  31. #130 Which of the lettered components shown in the illustration indicates the high pressure cutout? GS-RA-12 illustration
  32. #133 In the illustrated refrigeration system, what is the proper name for the component labeled "A"? GS-RA-12 illustration
  33. #140 Seawater or low temperature central fresh water is typically provided to a ship's stores refrigeration plant for what purpose?
  34. #141 Heat is removed from the refrigerant circulating through the refrigeration system, shown in the illustration, by which component? GS-RA-12 illustration
  35. #145 If there is a "large" release of R-134a refrigerant gas in a confined area, which of the following statements would be true?
  36. #147 Inhalation of high concentrations of chlorofluorocarbon refrigerants (CFCs) may have which of the following effects?
  37. #148 The FIRST thing to do to ensure that a refrigeration unit will not start while undergoing repairs is to do what?
  38. #152 In the presence of an open flame or hot surfaces, chlorinated fluorocarbon refrigerants decomposes and form what chemical substance?
  39. #166 In the illustrated refrigeration system, what is the proper name for the component labeled "A"? GS-RA-12 illustration
  40. #169 What is the drive arrangement of refrigeration compressor shown in figure "B" of the illustration? GS-RA-41 illustration
  41. #179 If a liquid drying agent is used in a refrigeration system already equipped with a solid drying agent, the liquid drying agent will cause what type of...
  42. #185 The device shown in the illustration which is used for removing moisture from the liquid refrigerant in the system is labeled with what letter? GS-RA-... illustration
  43. #186 Which of the following dehydrators or combination filter/driers features a core that can be replaced when the desiccant becomes saturated with moistur... illustration
  44. #191 The fluid used as a source of actuating power against the underside of the unloader power element piston of the refrigeration compressor capacity cont... illustration
  45. #196 A box solenoid valve used in a multi-box refrigeration system is operated by electro- magnetic action by what control device?
  46. #200 Which of the following electrically operated refrigeration system valves would be most appropriate for use as a 2 position diverting hot gas bypass so... illustration
  47. #203 Which of the following statements is true? GS-RA-12 illustration
  48. #204 A container unit's microprocessor-controlled temperature controller is set at -28.9 ° C, appropriate for a frozen cargo of ice cream. In this mode of... illustration
  49. #206 As shown in the illustrated refrigeration system piping schematic diagram with the various accessories and controls and equipped with an air-cooled co... illustration
  50. #207 If it is necessary to increase the operating head pressure of the refrigeration system using the device shown in the illustration, what should be done... illustration
  51. #208 In a refrigeration system, the valve shown in the illustration is used for what purpose? GS-RA-14 illustration
  52. #209 The set point adjustment of the device shown in the illustration is made by rotating what component? GS-RA-14 illustration
  53. #211 Which of the following illustrated expansion valves is designed to maintain a constant evaporator pressure rather than a constant evaporator superheat... illustration
  54. #214 In addition to the indicated gauge pressure, what other information is presented on the compound gauge for the hypothetical refrigerant illustrated? G... illustration
  55. #215 Which lettered component, shown in the illustration, indicates the location of the receiver? GS-RA-12 illustration
  56. #217 As shown in the illustrated LP centrifugal chiller pressure maintenance system, what is its functional purpose? GS-RA-40 illustration
  57. #218 What is the purpose of the pressure transducer as shown in the illustration? GS-RA-17 illustration
  58. #222 If the valve labeled "D" in the illustration is a suction service valve, what will the port labeled "7" be connected to? GS-RA-08 illustration
  59. #225 Which of the lettered components shown in the illustration indicates the high pressure cutout? GS-RA-12 illustration
  60. #232 Seawater or low temperature central fresh water is typically provided to a ship's stores refrigeration plant for what purpose?
  61. #233 Heat is removed from the refrigerant circulating through the refrigeration system, shown in the illustration, by which component? GS-RA-12 illustration
  62. #237 Through which of the components shown in the illustration is flash gas formation a normal occurrence? GS-RA-25 illustration
  63. #238 In the multi-evaporator refrigeration system shown in the illustration, what is the proper name for the valve labeled "29"? GS-RA-12 illustration
  64. #242 Which of the following illustrated expansion valves is designed to maintain a constant evaporator pressure rather than a constant evaporator superheat... illustration
  65. #243 Which of the following illustrated thermal expansion valves would be appropriate to use on an evaporator coil with a 2 psi pressure drop, where extern... illustration
  66. #247 Of the various possible methods shown in the illustration, which is the correct method of attaching a TXV feeler bulb to a small large line (7/8" and... illustration
  67. #254 Which of the listed statements describes the method used to determine the amount of superheat present in the suction gas leaving the evaporator coil?... illustration
  68. #257 Which of the following conditions will occur if the power element of the thermostatic expansion valve shown in the illustration loses its charge? GS-R... illustration
  69. #262 If the needle and seat assembly is excessively eroded, the valve cage assembly can be replaced. In replacing the original valve cage assembly rated at... illustration
  70. #265 Concerning frost appearing on one set of evaporator coils of a multi-box, direct expansion type refrigeration system, what is true?
  71. #273 You are checking the supply chilled water temperature thermistor probe on a high- pressure hermetic centrifugal chiller. Using the illustrated chart,... illustration
  72. #276 A high-pressure centrifugal chiller currently charged with R-134a is being evaluated for the need for leak testing. Using the leak-test procedures dec... illustration
  73. #284 After the refrigerant has been recovered, leaks repaired if necessary, the system ideally should undergo a dehydration evacuation prior to recharging... illustration
  74. #286 An air-cooled refrigerated container unit using R-134a as a refrigerant has a box temperature set point of -15 °F, but it is currently operating with... illustration
  75. #304 What must be done, at a minimum, before a system can legally be opened up for repairs while adhering to the prohibition against the venting of halogen...
  76. #306 As shown in figure "B" of the illustrated self-contained recovery unit connection diagrams, what is the recovery method supported by the connection sc... illustration
  77. #314 As shown in the illustrated flow diagram for a self-contained recovery unit designed for the recovery of refrigerants from high pressure appliances as... illustration
  78. #318 Which of the illustrated devices would be the LEAST accurate for the purposes of weighing-in a refrigerant charge? GS-RA-45 illustration
  79. #320 Which of the illustrated valves is used to gain access to a hermetic system and features a Schrader core valve which is unseated by the core depressor... illustration
  80. #324 Using the device shown in the illustration, which of the following statements is true when adding refrigerant as a vapor to the low side of the refrig... illustration
  81. #342 In the presence of an open flame or hot surfaces, chlorinated fluorocarbon refrigerants decomposes and form what chemical substance?
  82. #344 Which of the following statements is true concerning the gauge labeled "A" of the illustrated gauge manifold set? GS-RA-01 illustration
  83. #345 Which of the following statements is true concerning the illustrated gauge manifold set? GS-RA-01 illustration
  84. #363 The introduction of outside air to the air conditioning system is 90°F with a relative humidity of 60%. The air has been conditioned to 70°F with a re... illustration
  85. #366 Which of the following is true concerning the class "D" air conditioning system shown in the following illustration? Refer to Illustration GS-RA-42 illustration
  86. #373 Using the illustrated chart giving the boiling point of moisture at various depths of vacuum, with an ambient temperature of 72 °F, what depth of vacu... illustration
  87. #389 In the illustrated refrigeration system, what is the proper name for the component labeled "A"? GS-RA-12 illustration
  88. #392 What is the drive arrangement of refrigeration compressor shown in figure "B" of the illustration? GS-RA-41 illustration
  89. #409 A box solenoid valve used in a multi-box refrigeration system is operated by electro- magnetic action by what control device?
  90. #413 Which of the following electrically operated refrigeration system valves would be most appropriate for use as a 2 position diverting hot gas bypass so... illustration
  91. #416 Which of the following statements is true? GS-RA-12 illustration
  92. #417 A container unit's microprocessor-controlled temperature controller is set at -28.9 ° C, appropriate for a frozen cargo of ice cream. In this mode of... illustration
  93. #423 The fluid used as a source of actuating power against the underside of the unloader power element piston of the refrigeration compressor capacity cont... illustration
  94. #424 During operating periods of a multi-box refrigeration system using a capacity controlled compressor, when all of the evaporators of a four box plant a... illustration
  95. #428 As shown in the illustrated refrigeration system piping schematic diagram with the various accessories and controls and equipped with an air-cooled co... illustration
  96. #429 If it is necessary to increase the operating head pressure of the refrigeration system using the device shown in the illustration, what should be done... illustration
  97. #430 In a refrigeration system, the valve shown in the illustration is used for what purpose? GS-RA-14 illustration
  98. #431 The set point adjustment of the device shown in the illustration is made by rotating what component? GS-RA-14 illustration
  99. #435 Which of the lettered components shown in the illustration indicates the high pressure cutout? GS-RA-12 illustration
  100. #440 In addition to the indicated gauge pressure, what other information is presented on the compound gauge for the hypothetical refrigerant illustrated? G... illustration

Refrigeration AC questions: what to expect

Q How many Refrigeration AC questions are in the Engine pool?

This retired set holds 134 Refrigeration AC questions the Coast Guard no longer draws on exams. They stay online for reference; the current Refrigeration AC module is the one to study.

Q What score do I need to pass the Refrigeration AC module?

Most USCG exam modules, including Refrigeration AC, require 70 percent to pass. Rules of the Road modules require 90 percent.

Q Are these the real USCG Refrigeration AC exam questions?

Yes. They are the published U.S. Coast Guard questions, matched to the National Maritime Center's 2026 sample examinations. Answer any question to see the correct choice, the USCG reference and the illustration where the question uses one.

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