HVAC Air Condition Esco 2024-2025 exam with correct answers., Exams of Refrigeration and Air Conditioning

Download HVAC Air Condition Esco 2024-2025 exam with correct answers. and more Exams Refrigeration and Air Conditioning in PDF only on Docsity! CSN AC 110 Esco Exam Practice questions with correct answers 1. Heat which causes a change in temperature of a substance is called; A. latent heat B. sensible heat C. superheat D. radiant heat - correct answer -B. sensible heat 2. Heat added to a substance without a raise in temperature; (example: liquid refrigerant to gas) this process is called? A. latent heat of vaporization B. latent heat of fusion. C. superheat of vaporization D. superheat of fusion - correct answer -A. latent heat of vaporization 3. Heat added to the refrigerant in a vapor state after the evaporation process is called; A. latent heat B. subcooling C. superheat D. specific heat - correct answer -C. superheat 4. A scroll compressor move refrigerant by means of; A. a piston B. an impeller C. vane and cam D. involute spirals - correct answer -D. involute spirals 5. The movement of heat by way of fluid (or air) is called; A. conduction B. convection C. radiation D. percussion - correct answer -B. convection 6. The movement of heat through a solid object is called; A. conduction B. convection C. radiation D. compression - correct answer -A. conduction 7. The standard unit for measuring the quantity of heat in a substance is; A. degrees Fahrenheit B. degrees Celsius C. degrees Rankin D. the British Thermal Unit (Btu) - correct answer -D. the British Thermal Unit (Btu) 8. A refrigerant gives up heat when; A. it condenses B. it evaporates C. it is compressed D. it vaporizes - correct answer -A. it condenses 9. Why must refrigerant in the suction line be slightly warmer than the saturation temperature? A. prevent liquid slugging of hte compressor B. prevent refrigerant vapor lock C. prevent the compressor from overheating D. prevent oil miscibility - correct answer -A. prevent liquid slugging of the compressor A. dry bulb temperature B. wet buldb dry depression C. dew point temperature D. condensate point - correct answer -C. dew point temperature 20. A compound pressure gauge measures; A. pressure and vacuum B. pressure and temperature C. pressure and humidity D. wet and dry bulb temperatures - correct answer -A. pressure and vacuum 21. A mechanical shaft seal is necessary on a; A. semi-hermetic compressor B. hermetic reciprocating compressor C. hermetic rotary compressor D. open drive compressor - correct answer -C. hermetic rotary compressor 22. Liquid slugging is; A. a pounding noise caused by liquid refrigerant in the suction line at the point of restriction B. noise caused by excessive liquid refrigerant in the condenser C. liquid refrigerant in the compressor clearance space D. excessive liquid refrigerant in the receiver - correct answer -C. liquid refrigerant in the compressor clearance space 23. The clearance of space in a reciprocating compressor; A has no effect on compressor capacity B. has an effect on compressor capacity C. varies depending on compressor speed D. is the same on all compressors - correct answer -B. has an effect on compressor capacity 24. Which of the following types of air conditioning compressors is most energy efficient? A. Reciprocating B. Centrigugal C. Rotary vane D. Scroll - correct answer -D scroll 25. Which of the following represent the right order for functions of a condenser? A. sub-cools, condenses, de-superheats B. de-superheats, condenses, sub-cools C. condenses, sub-cools, de-superheats D. sub-cools, de-superheats, condenses - correct answer -B. de-superheats, condenses, sub-cools 26. Refrigerant R-134a vapor enters the condenser at 124 psig, 100°F. it leaves as a liquid from the condenser sub-cooled 20°F. and the pressure will be approximately; A. 76 psig B. 87 psig C. 106 psig D. 124 psig - correct answer -B. 87 psig 27. There are threee basic types of condensers, the air cooled, the water cooled and the ___________ cooled. A. evaporative B. expansion C. gas D. double pipe - correct answer -A. evaporative 28. If 10LBS refrigerant pass through a water cooled condensers and lose 20 BTUs/LB of heat and 10 LBS of 80F water enter and pass through this condenser. What will the temperature of the water leaving the condenser be? A. 80°F B. 95°F C. 100°F D. 110°F - correct answer -C. 100°F 29. The heat removed from the refrigerant by the condenser is; A. sensible heat only B. latent heat only C. both sensible and latent heat D. neither sensible or latent heat - correct answer -C. both sensible and latent heat 30. An Energy Recovery ventilator is; A. a low ambient air temperature control B. to recover the warm air from the condenser C. a high efficient attic ventilator system D. an air to air heat-exchanger to recover heat - correct answer -D. an air to air heat-exchanger to recover heat 31. When testing the efficiency of an air cooled condenser, the refrigerant condensing temperature should be approximately _____ higher than the entering air temperature? A. 30°F B. 40°F C. 100°F D. 120°F - correct answer -A. 30°F 32. When testing the efficiency of a water cooled condenser, the refrigerant condensing temperature should be approximately A. 10°F B. 30°F C. 40°F C. flood the evaporator D. starve the evaporator - correct answer -B. close 42. a rise in evaporator pressure causes the automatic expansion valve to begin to; A. open B. close C. flood the evaporator D. starve the evaporator - correct answer -A. open A thermal-electric (solid state) expansion valve is controlled by; A. suction pressure B. NTC thermistor C. thermal bulb D. external equalizing port - correct answer -B. NTC thermistor 44. In a direct expansion (DX) evaporator system, the refrigerant enters the evaporator as; A. liquid only B. vapor only C. a mixture of liquid with some "flash-gas" D. superheated vapor only - correct answer -C. a mixture of liquid with some "flash-gas" 45. which of the following is the most important consideration in the selection of an evaporator coil? Match the coil to the; A. sensible capacity of the condensing unit B. latent capacity fo the condensing unit C. latent capacity and outdoor design temperature D. condensing unit and the latent/sensible loads - correct answer -D. condensing unit and the latent/sensible loads 46. In the evaporator; A. latent heat is transferred form the refrigerated space to the refrigerant B. latent heat is transferred from the refrigerant to the refrigerated space C. the refrigerant changes form a vapor to a liquid D. the refrigeration system reaches its highest pressure - correct answer -A. latent heat is transferred form the refrigerated space to the refrigerant 47. A liquid line filter-drier should be placed between the; A. evaporator and the compressor B. compressor and the condenser C. condenser and the metering device D. metering device and ht evaporator - correct answer -C. condenser and the metering device 48. the only way to minimize flash gas is by; A. increase the superheating setting on the thermostatic expansion valve to correspond with the compressor horsepower B. change the evaporator fan to a lower setting C. sub-cooling the liquid refrigerant entering the metering device closer to the evaporator temperature D. change the evaporator fan speed to a higher setting - correct answer -C. sub-cooling the liquid refrigerant entering the metering device closer to the evaporator temperature 49. A liquid receiver is used to; A prevent liquid refrigerant from reaching the compressor B. separate oil from the liquid refrigerant C. store liquid refrigerant D. receive and store vapor refrigerant - correct answer -C. store liquid refrigerant 50. An accumulator is used to; A. prevent liquid refrigerant from reaching the compressor B. separate oil from the liquid refrigerant C. store liquid refrigerant D. receive and store vapor refrigerant - correct answer -A. prevent liquid refrigerant from reaching the compressor A sight glass would normally be located A. in the liquid line, before the metering device B. in the liquid line, after the metering device C in the suction line, before the compressor D. in the suction line, after the compressor - correct answer -A. in the liquid line, before the metering device 52. Bubbles in a sight glass could be an indication of; A. an overcharge of refrigerant B. low compressor capacity C. TXV with an excessive superheat setting D. a refrigerant blend with a high temperature glide - correct answer -D. a refrigerant blend with a high temperature glide 53. The oil separator is installed in the A. Suction line B liquid line C.. Discharge line. D. Distribution line. - correct answer -C.. Discharge line. 54 which of the following is true of a solenoid valve in a pump down system? A it is located after the metering device B it is located before the metering device C., it is located after the evaporator D it is used instead of a metering device - correct answer -B it is located before the metering device A flush and purge the system with liquid liquid be apply heat to the accumulator of the system B apply heat to the accumulator of the system C use the largest vacuum pump available with long hoses to allow condensing D triple evacuate the system to 500 µm with a deep vacuum pump - correct answer -D triple evacuate the system to 500 µm with a deep vacuum pump 65. What type of gauge is used to measure microns? A high pressure gauge B a compound gauge C an electronic vacuum gauge D a mercury manometer - correct answer -C an electronic vacuum gauge Water will vaporized at what temperature in a 28 inch mercury vacuum A 100° B 10° C 212° ° D 150° - correct answer -A 100° 67. After a system has been opened, and the compressor changed the service technician must. A add virgin refrigerant only after pulling a vacuum for one hour B replace the filter, dryer, leak, check, evacuate, and charge C evacuate and charge liquid, refrigerant into the low side of the system D evacuate and charge - correct answer -B replace the filter, dryer, leak, check, evacuate, and charge 68. Back seating a two Way service valve results in. A open service port with normal system flow B closed service port with normal system flow C open service port with the system flow blocked D closed service port with the system flow blocked - correct answer -B closed service port with normal system flow 69 the R410A compound gauge reads 124 psig and the suction line temperature at the condensing unit is 54°F. What is the operating system super heat? A 96° B 30° C 12° D 6° - correct answer -C 12° 70when topping off an operating system, containing a blended refrigerant A introduce the refrigerant as a liquid into the low side, using a throttling valve B introduce the refrigerant as a vapor into the low side, using a throttling valve C. introduce the refrigerant as a liquid through the high side D weigh in the refrigerant as a vapor into the low side - correct answer -A introduce the refrigerant as a liquid into the low side, using a throttling valve 71. A partially clogged capillary tube can cause. A low Head pressure B a starved condenser C a starved evaporator D a flooded evaporator - correct answer -C a starved evaporator 72 the R134A high pressure gauge reads 146 psig and the liquid line temperature at the condensing unit is 95°. What is the operating system sub cooling? A 238° B 48° C 35° D 15° - correct answer -D 15 73 an overcharge of refrigerant will cause A increased head pressure B decreased head pressure C. bubbles in the sight glass D frost on the condenser - correct answer -A increased head pressure 74 for a customer complains that their air conditioning system is running constantly, but not cooling enough. The suction line is very cold and the compressor is sweating. The most likely cause is. A low refrigerant charge B a restriction of the return air or a dirty evaporator C high humidity conditions with a blocked condensate tube D the thermostat is set too low - correct answer -B a restriction of the return air or a dirty evaporator 75. A drain trap should be installed on a split system when the. A water is recycled for green incentives B condensate line goes to an open drain C air handler drain is on the positive air D air handler drain is on the negative air side - correct answer -D air handler drain is on the negative air side 76. A customer reports that their residential split system had a compressor replaced last week by another service company. Now the unit is not cooling properly. When you arrive and inspect the unit, you find that the evaporator seems to be starved for refrigerant. On examining the condensing unit, you find that the liquid line is sweating where it leaves the dryer. This is most likely the result of. A debris from the burned out compressor has clogged the dryer B air in the system C a defective replacement compressor D refrigerant overcharge - correct answer -A debris from the burned out compressor has clogged the dryer B 15 psig C 20 psig D 25 psig - correct answer -B 15 psig 87. When connecting copper to steel, the recommended braising filler alloy is a. A 45% silver alloy B copper/phosphorus alloy C 50/50 sold or alloy D 5% silver alloy - correct answer -A 45% silver alloy 88. Solid contaminants, such as sludge and carbon, from a severe hermetic compressor motor burnout are best removed. A by blowing the system out with refrigerant, and then installing filter/dryers in both the liquid and suction lines B by flushing the system out, and then installing filter/dryers in both the liquid and suction lines C by blowing the system out with compressed air, and then installing filter/dryers in both the liquid and suction line D by installing filter/dryers in both the liquid and suction lines - correct answer -B by flushing the system out, and then installing filter/dryers in both the liquid and suction lines 89. If the cut off plate is removed from a blower assembly, how would this affect blower performance? A it would increase airflow B it would reduce airflow C blower motor performance would increase D blower motor would operate correctly - correct answer -B it would reduce airflow 90 at a residential service call, no cooling complaint, the service technician finds the unit to be completely out of refrigerant. The technician decides to use a trace amount of refrigerant and what, in order to pressurize the system. A compressed air B oxygen C an inert gas D carbon monoxide - correct answer -C an inert gas 91. A technician has found an air conditioning system with a leak in the liquid line. After the line is repaired, the system is evacuated and properly recharged. When the system is started, the compressor is noisy and running hot. The most probable cause of the noise is A refrigerant overcharge B air in the system C low oil in the system D refrigerant undercharge - correct answer -C low oil in the system 92 and air-conditioning system that is oversized can cause A increased compressor life B better comfort range C improved dehumidification of the conditioned space. D inefficient dehumidification of the conditioned space - correct answer -D inefficient dehumidification of the conditioned space 93 while troubleshooting a residential split system, the service technician, finds low operating pressures and low system amperage draw. This could be an indication of. A low airflow across the evaporator B high ambient C a dirty condenser D air in the system - correct answer -A low airflow across the evaporator 94. Air or other non-condensable gases in capillary tube air conditioning system will cause these symptoms. A high suction pressure and low discharge pressure B high suction pressure and high discharge pressure C low suction pressure and low discharge pressure D low suction pressure and high discharge pressure - correct answer -B high suction, pressure and high discharge pressure 95 A refrigerant over charge in a capillary tube air conditioning system will cause these symptoms A high suction pressure and low discharge pressure B high suction pressure and high discharge pressure C low suction pressure and low discharge pressure D low suction pressure and high discharge pressure - correct answer -B high suction, pressure and high discharge pressure 96. A compressor that has a broken read valve will cause these symptoms. A high suction pressure and low discharge pressure B high suction pressure and high discharge pressure C low suction pressure and low discharge pressure D low suction pressure and high discharge pressure - correct answer -A high suction, pressure and low discharge pressure 97. A low refrigerant charge in an air conditioning system will cause these symptoms. A high suction pressure and low discharge pressure B high suction pressure and high discharge pressure C low suction pressure and low discharge pressure D low suction pressure and high discharge pressure - correct answer -C low suction, pressure and low discharge pressure 98 A TEV sensing bulb, which becomes detached from the suction line, will cause these symptoms A high suction pressure and lower than normal discharge pressure. B high suction pressure and higher than normal discharge pressure. C low suction pressure and lower than normal discharge pressure. D low suction pressure and higher than normal discharge pressure. - correct answer -B high suction pressure and higher than normal discharge pressure.