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Engine · 623 questions

Refrigeration AC - USCG Exam Questions

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.

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All Refrigeration AC questions

Questions 401–500 of 623 · page 5 of 7

  1. #732 The coil temperature measured at the expansion valve sensing bulb of an operating system is 10°F. The low side pressure with the compressor runnin... illustration
  2. #734 Which of the following statements describes the accepted method for testing a thermostatic expansion valve?
  3. #736 Moisture in a refrigeration system can cause which of the following conditions?
  4. #737 In a low-pressure refrigeration system, excessive running of the purge recovery unit generally indicates which probable condition?
  5. #739 Excessive moisture being collected in the purge unit of a low-pressure refrigeration system could indicate which probable condition?
  6. #740 An evaporator coil of a single evaporator, air-cooled refrigerator is accumulating excessive frost due to a failure of the defrost mechanism. If the r...
  7. #749 In a refrigeration system, the bulb for the thermal expansion valve is always located where?
  8. #751 In a vapor compression type refrigeration cycle, the refrigerant temperature decreases the most when passing through which system component?
  9. #752 When the sensing bulb of a thermostatic expansion valve is charged with a fluid different from the charge used in the system, what name of the charge...
  10. #754 The thermostatic expansion valve in a refrigeration system further opens when the diaphragm flexes downward. With all other conditions being the same,...
  11. #755 A typical shipboard domestic multi-box refrigeration system operates with one compressor and condenser. What is the purpose of the sensing line connec...
  12. #757 Concerning the proper installation of the sensing bulb of a thermal expansion valve that is attached to the evaporator tail coil on a horizontal run,...
  13. #759 In refrigeration systems with multiple evaporators, the metering of refrigerant to each refrigerated space evaporator is accomplished by what device?
  14. #766 The low-pressure cutout switch settings vary with the refrigerant used and the temperature application. If the low-pressure cutout switch for a partic...
  15. #768 The sensing line for the low-pressure cutout switch for a refrigeration system is typically connected at what location?
  16. #772 Which of the listed operations will cause an automatically controlled refrigeration compressor to restart if the system features a pump down cycle?
  17. #779 What would be an indication that the vegetable box back pressure regulator is set too low?
  18. #783 Corrosion has wasted away large sections of the fins attached to an air conditioning cooling coil. In assessing the effects on the system you would as...
  19. #784 Sludge may form in the crankcase of an air conditioning compressor as a result of what condition?
  20. #789 While securing the air conditioning compressor you close the suction valve and the compressor stops after a short period of time. Subsequent attempts...
  21. #792 EPA Clean Air Act rules permit refrigerant to be released to the atmosphere under which of the following conditions?
  22. #793 All shipboard personnel responsible for the maintenance and repair of air conditioning systems using refrigerants covered under the EPA Clean Air Act...
  23. #794 If you find the pressure of a refrigeration system containing a Class I or Class II refrigerant to be opened for the accomplishment of repairs is 0 ps...
  24. #795 What would be an example of a small appliance as defined in the EPA Clean Air Act rules?
  25. #796 Persons recovering refrigerant from small appliances must be certified as what type of technician under the EPA Clean Air Act rules?
  26. #797 Within the territorial limits of the United States, violations of the Clean Air Act of 1990, that includes the intentional release of R-11, R-12, R-22...
  27. #798 Which best defines a "Type I" small refrigeration appliance according to the EPA Regulations Section 608?
  28. #799 According to the EPA Clean Air Act rules, what is true concerning refrigerant leaks in a small hermetically sealed shipboard water cooler with a 20 ou...
  29. #800 When recovering R-12 from a small appliance with a working compressor, using a recovery device manufactured after November 15, 1993, what percentage o...
  30. #801 As shown in the illustrated LP centrifugal chiller high efficiency purge recovery unit piping schematic, what statement is true concerning the vacuum... illustration
  31. #806 The air temperature associated with a direct reciprocating air conditioning plant is found to be too warm, and the compressor is not operating. A serv...
  32. #807 In an air conditioning system, low discharge head pressure associated with a reciprocating compressor can be the result of what condition?
  33. #808 The surging that occurs in a centrifugal air conditioning compressor is a result of what conditions?
  34. #811 A reciprocating multi-cylinder air conditioning or refrigeration compressor starts cycling on/off. What would one do to prevent cycling?
  35. #836 While troubleshooting intermittent failures of the ship service refrigeration system you suspect the problem is with the lube oil pressure differentia...
  36. #837 The compressor on the ships service refrigeration system starts up but stops after a brief period of running. Subsequent attempts to start it produce...
  37. #840 With regards to shipboard refrigeration systems, after July 1, 1992, what action became illegal?
  38. #841 Refillable tanks used to ship CFC and HCFC refrigerants or used to recover these refrigerants must meet the standards of what entity?
  39. #842 Coast Guard Regulations (46 CFR Part 113) require refrigerated spaces that can be locked from the outside and that cannot be opened from the inside to...
  40. #843 According to 46 CFR, Part 58, for protection purposes, what is required of all refrigeration systems?
  41. #848 While recharging a commercial type refrigerator, with a hermetically sealed compressor with no pressure gauges, what could you use or do to achieve a...
  42. #849 Which of the illustrated valves is used to gain access to a hermetically sealed system and features a Schrader core valve which is unseated by the cor... illustration
  43. #850 You have completed repairs to a small galley refrigerator which uses a capillary tube and a hermetic compressor. The repairs required complete evacuat...
  44. #853 Referring to illustrated diagram, what type of HVAC system is shown? Illustration GS-RA-42 illustration
  45. #858 Referring to the illustrated single zone HVAC system diagram, what statement is true concerning the damper controls? Illustration GS-RA-09 illustration
  46. #859 The set point adjustment of the device shown in the illustration is made by rotating what component? Illustration GS-RA-14 illustration
  47. #860 As shown in the illustrated refrigeration system piping schematic diagram with the various accessories and controls and equipped with an air-cooled co... illustration
  48. #861 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
  49. #862 Excessive moisture being collected in the purge unit of a low-pressure refrigeration system could indicate which probable condition?
  50. #863 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
  51. #864 What is a quick method used to test a water-cooled condenser for the presence of a refrigerant leak without actually pinpointing the actual location?
  52. #865 What must be done to use standard leak detection methods on a low-pressure refrigeration system charged with refrigerant?
  53. #866 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...
  54. #867 What is the correct color-coding of refrigerant recovery cylinders regardless of the refrigerant contained within?
  55. #868 What is the color-coding for a storage container of R-134a refrigerant?
  56. #869 Which of the lettered components shown in the illustration indicates the high-pressure cutout? Illustration GS-RA-12 illustration
  57. #870 When the relief valve opens on a refrigeration compressor discharge line, it discharges high-pressure refrigerant vapor to what location?
  58. #871 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
  59. #872 In the multi-evaporator refrigeration system shown in the illustration, what is the proper name for the valve labeled "29"? Illustration GS-RA-12 illustration
  60. #873 Through which of the components shown in the illustration is flash gas formation a normal occurrence? Illustration GS-RA-25 illustration
  61. #874 After the refrigerant has been recovered, leaks repaired if necessary, the system ideally should undergo a dehydration evacuation prior to recharging... illustration
  62. #875 In addition to the indicated gauge pressure, what other information is presented on the compound gauge for the hypothetical refrigerant illustrated? I... illustration
  63. #876 You are checking the supply chilled water temperature thermistor probe on a high-pressure hermetic centrifugal chiller. Using the illustrated chart, w... illustration
  64. #877 In the presence of an open flame or hot surfaces, chlorinated fluorocarbon refrigerants decompose and form what chemical substance?
  65. #878 An evaporator coil of a single evaporator, air-cooled refrigerator is accumulating excessive frost due to a failure of the defrost mechanism. If the r...
  66. #879 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
  67. #880 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
  68. #881 Minor repairs may be performed on low-pressure refrigerant systems without recovering the refrigerant charge if the pressure in the system is raised t...
  69. #882 The most cost-effective method of recovering refrigerant from a low-pressure chiller with more than 500 lbs of refrigerant and to meet EPA requirement...
  70. #883 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
  71. #884 Regarding heat transfer principles, which of the following are true?
  72. #885 In a low-pressure refrigeration system, excessive running of the purge recovery unit generally indicates which probable condition?
  73. #886 Heat is removed from the refrigerant circulating through the refrigeration system, shown in the illustration, by which component? Illustration GS-RA-1... illustration
  74. #887 When the relief valve opens on a refrigeration compressor discharge line, it discharges high-pressure refrigerant vapor to what location?
  75. #888 Which of the lettered components shown in the illustration indicates the high-pressure cutout? Illustration GS-RA-12 illustration
  76. #889 The rupture disc on a low-pressure centrifugal refrigeration unit is used as an overpressure protection device and is set to relieve at 15 psig and is...
  77. #890 Heat is removed from the refrigerant circulating through the refrigeration system, shown in the illustration, by which component? Illustration GS-RA-1... illustration
  78. #891 Sea water or low temperature central fresh water is typically provided to a ship's stores refrigeration plant for what purpose?
  79. #892 Which of the following conditions will occur if the power element of the thermostatic expansion valve shown in the illustration loses its charge? Illu... illustration
  80. #893 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
  81. #894 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
  82. #895 Which of the illustrated devices would be the LEAST accurate for the purposes of weighing-in a refrigerant charge? Illustration GS-RA-45 illustration
  83. #896 Which of the following illustrated expansion valves is designed to maintain a constant evaporator pressure rather than a constant evaporator superheat... illustration
  84. #897 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
  85. #898 Why is a purge recovery unit typically fitted on low-pressure centrifugal chillers?
  86. #899 Minor repairs may be performed on low-pressure refrigerant systems without recovering the refrigerant charge if the pressure in the system is raised t...
  87. #900 The most cost-effective method of recovering refrigerant from a low-pressure chiller with more than 500 lbs. of refrigerant and to meet EPA requiremen...
  88. #901 As shown in the illustrated refrigeration system piping schematic diagram with the various accessories and controls and equipped with an air-cooled co... illustration
  89. #902 In a refrigeration system, the valve shown in the illustration is used for what purpose? Illustration GS-RA-14 illustration
  90. #903 The set point adjustment of the device shown in the illustration is made by rotating what component? Illustration GS-RA-14 illustration
  91. #904 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
  92. #905 If the valve labeled "D" in the illustration is a suction service valve, what will the port labeled "7" be connected to? Illustration GS-RA-08 illustration
  93. #906 Refrigeration system isolation valves are specially designed with a backseat, as well as a front seat. For what purpose are these valves designed in t...
  94. #907 In addition to the indicated gauge pressure, what other information is presented on the compound gauge for the hypothetical refrigerant illustrated? I... illustration
  95. #908 What is the purpose of the pressure transducer as shown in the illustration? Illustration GS-RA-17 illustration
  96. #909 Which lettered component, shown in the illustration, indicates the location of the receiver? Illustration GS-RA-12 illustration
  97. #910 During normal operation, traditionally, how has most of the refrigerant released to the atmosphere from low-pressure systems?
  98. #911 The device shown in the illustration which is used for removing moisture from the liquid refrigerant in the system is labeled with what letter? Illust... illustration
  99. #912 Which of the following dehydrators or combination filter/driers features a core that can be replaced when the desiccant becomes saturated with moistur... illustration
  100. #913 In the illustrated refrigeration system, what is the proper name for the component labeled "A"? Illustration GS-RA-12 illustration

Refrigeration AC questions: what to expect

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

There are 623 Refrigeration AC questions on this site, every one released by the U.S. Coast Guard or taken from the National Maritime Center's sample examinations, with its correct answer. The exam draws its Refrigeration AC module from the same pool.

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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