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CSN AC 110 ESCO EXAM QUESTIONS WITH
CORRECT VERIFIED SOLUTIONS 100% PASS
(LATEST 2025/2026)
A mechanical shaft seal is necessary on a; A. semi-hermetic compressor B. hermetic reciprocating compressor C. hermetic rotary compressor D. open drive compressor - ANS ✓C. hermetic rotary compressor 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 - ANS ✓C. liquid refrigerant in the compressor clearance space 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 - ANS ✓B. has an effect on compressor capacity Which of the following types of air conditioning compressors is most energy efficient?
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A. Reciprocating B. Centrifugal C. Rotary vane D. Scroll - ANS ✓D scroll 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 - ANS ✓B. de-superheats, condenses, sub-cools 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 - ANS ✓B. 87 psig 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 - ANS ✓A. evaporative 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
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A. 10°F
B. 30°F
C. 40°F
D. 50°F - ANS ✓A. 10°F
- The first function a condenser must perform is to _______ the refrigerant before condensing can occur. A. superheat B. de-superheat C. compress D. sub-cool - ANS ✓B. de-superheat
- A thermostatic expansion valve is designed to maintain; A. constant evaporator temperature B. constant refrigerant flow C. constant evaporator superheat D. constant evaporator pressure - ANS ✓C. constant evaporator superheat
- The automatic expansion valve is designed to maintain; A. constant evaporator temperature B. constant refrigerant flow C. constant evaporator superheat D. constant evaporator pressure - ANS ✓D. constant evaporator pressure
- The thermostatic expansion valve has three operating pressures; A. evaporator pressure, spring pressure & equalizer line pressure B. evaporator pressure, spring pressure & condensing bulb pressure C. evaporator pressure, spring pressure & liquid bulb pressure
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D. evaporator pressure, spring pressure & sensor bulb pressure - ANS ✓D. evaporator pressure, spring pressure & sensor bulb pressure
- When mounting a thermostatic expansion valve sensor bulb, which fo the following is not true? A. the contact surfaces must be clean B. it must be tightly clamped to the suction line C. it must be insulated from ambient temperature D. it must be installed lower than the valve body - ANS ✓D. it must be installed lower than the valve body
- In an air conditioning system that uses a thermostatic expansion valve, the temperature of the evaporator outlet will usually be; A. cooler than the evaporator inlet B. warmer than the evaporator inlet C. the same as the evaporator inlet D. unchanged by superheat - ANS ✓B. warmer than the evaporator inlet
- An automatic expansion valve is best suited; A. when the system load remains fairly constant B. when the system load varies greatly C. when the compressor must start often D. when multiple evaporators are used - ANS ✓A. when the system load remains fairly constant
- Which of the following is not true of a capillary tube metering device? A. they have no moving parts B. they allow pressures to equalize after the compressor shuts down C. they maintain a constant evaporator temperature
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- 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 - ANS ✓D. condensing unit and the latent/sensible loads
- 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 - ANS ✓A. latent heat is transferred form the refrigerated space to the refrigerant
- 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 - ANS ✓C. condenser and the metering device
- 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
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D. change the evaporator fan speed to a higher setting - ANS ✓C. sub-cooling the liquid refrigerant entering the metering device closer to the evaporator temperature
- 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 - ANS ✓C. store liquid refrigerant
- 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 - ANS ✓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 - ANS ✓A. in the liquid line, before the metering device
- 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 - ANS ✓D. a refrigerant blend with a high temperature glide
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- The oil pressure safety switch is operated by. A the sum of suction pressure and oil pressure B the sum of oil, pressure and crank case pressure C the difference between crank case, pressure and oil pressure D the difference between head pressure and oil pressure - ANS ✓C the difference between crank case, pressure and oil pressure
- A low pressure cut off switch is used to. A establish a minimum operating pressure in the evaporator B prevent condensing pressure from reaching dangerously high levels C sense, oil pressure in the lower portion of the compressor D prevent lo oil pressure in the crank case - ANS ✓A establish a minimum operating pressure in the evaporator 59.A partially iced over evaporator can be caused by. A an overcharge Be excessive airflow C. and under charge D high indoor humidity - ANS ✓C. an under charge 60 This can be used for leak detection with all high pressure refrigerants A soap bubbles B halide torch C open flame D electronic halogen detector - ANS ✓A soap bubbles
- The flow rate of a TXV used in our 410 a systems as compared to R systems is A equal
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B approximately 40% to 70% higher C approximately 15% greater D approximately 15% less - ANS ✓D approximately 15% less
- When using an electronic leak detector, the sensor probe. A must be moved around suspected area as fast as possible B must be exposed to a large amount of refrigerant for calibration C. should be moved at approximately 1 inch every two seconds D is not affected by dirt or oil - ANS ✓C. should be moved at approximately 1 inch every two seconds
- Moisture in a refrigeration system will cars. A low head pressure B high suction pressure C evaporator icing D compressor failure - ANS ✓D compressor failure
- In order to remove as much moisture as possible from a system. A flush and purge the system with 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 - ANS ✓D triple evacuate the system to 500 μm with a deep vacuum pump
- What type of gauge is used to measure microns? A high pressure gauge B a compound gauge
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D 6° - ANS ✓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 - ANS ✓A introduce the refrigerant as a liquid into the low side, using a throttling valve
- A partially clogged capillary tube can cause. A low Head pressure B a starved condenser C a starved evaporator D a flooded evaporator - ANS ✓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° - ANS ✓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 - ANS ✓A increased head pressure
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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 - ANS ✓B a restriction of the return air or a dirty evaporator
- 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 - ANS ✓D air handler drain is on the negative air side
- 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 - ANS ✓A debris from the burned out compressor has clogged the dryer 77 what is the generally accepted range for evaporator airflow in CFM's per ton of residential air-conditioning? A 150 to 250
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C high head pressure D frost on the evaporator - ANS ✓C high head pressure
- Frost on the suction line indicates. A that it's temperature is below the dewpoint and below 32° B a flooded evaporator C low superheat, setting D refrigerant over charged - ANS ✓A that it's temperature is below the dewpoint and below 32°
- An increase in head pressure causes how much refrigerant to flow through a capillary tube. A more B less C no D the same amount of - ANS ✓A more 84 with an automatic expansion valve, an increase in evaporator load will cause the A suction pressure to decrease B automatic expansion valve to close C evaporator superheat to drop D automatic expansion valve to open - ANS ✓B automatic expansion valve to close
- When a TEV or a capillary tube is used as a metering device, a low refrigerant charge will cause. A high suction pressure B high head pressure C low superheat
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D low head pressure - ANS ✓D low head pressure 86 what is the maximum operating pressure setting for an acetylene torch? A 10 psig B 15 psig C 20 psig D 25 psig - ANS ✓B 15 psig
- 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 - ANS ✓A 45% silver alloy
- 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 - ANS ✓B by flushing the system out, and then installing filter/dryers in both the liquid and suction lines
- 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
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A low airflow across the evaporator B high ambient C a dirty condenser D air in the system - ANS ✓A low airflow across the evaporator
- 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 - ANS ✓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 - ANS ✓B high suction, pressure and high discharge pressure
- 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 - ANS ✓A high suction, pressure and low discharge pressure
- A low refrigerant charge in an air conditioning system will cause these symptoms.
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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 - ANS ✓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. - ANS ✓B high suction pressure and higher than normal discharge pressure. 99 A faulty condenser fan motor on 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 - ANS ✓B high suction pressure and high discharge pressure 100 A dirty evaporator in an air conditioning system will cause the 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 - ANS ✓C low suction pressure and low discharge pressure
