ESCO Air Conditioning Exam with Correct Answers, Exams of Refrigeration and Air Conditioning

Download ESCO Air Conditioning Exam with Correct Answers and more Exams Refrigeration and Air Conditioning in PDF only on Docsity!

ESCO Air Conditioning Exam with

correct answers

Heat which causes a change in temperature of a substance is called - correct answer -Sensible heat Heat added to a substance without a rise in temperature - correct answer -Latent heat Heat added to the refrigerant in a vapor state after the evaporation process is called - correct answer - Superheat Scroll compressor move refrigerant by - correct answer -Involute Spirals The movement of heat by way of fluid is called - correct answer -Convection The movement of heat by direct contact is - correct answer -Conduction The standard unit for measuring the quantity of heat in a substance is - correct answer -BTUs Refrigerant gives up heat when - correct answer -It condenses Why must refrigerant in the suction line be slightly warmer than the saturation temperature? - correct answer -Prevent liquid slugging of the compressor The state of the refrigerant in the suction line should be - correct answer -Low pressure / Low temperature vapor The state of the refrigerant entering the condenser is - correct answer -High pressure / Highly superheated vapor The evaporator - correct answer -Transfers heat from the refrigerated space to the refrigerant

Which of the following is not a thermodynamic property of refrigerants - correct answer -Flammability The sequential order of steps in the vapor compressions process are - correct answer -Compression, Condensation, Expansion, Vaporization If a 30 pound cylinder of reclaimed R 410 a refrigerant has been stored overnight at 70° the pressure in the cylinder should be approximately - correct answer -201 psig Fan airflow pressures are usually measured in - correct answer -Inches of water column 0 pounds per square inch absolute is - correct answer -A pressure which cannot be further reduced 0 pounds per square inch gauge is - correct answer -The same as atmospheric pressure The temperature at which moisture will start to condense from the air is called - correct answer -Dew point temperature A compound pressure gauge measures - correct answer -Pressure and vacuum Mechanical shaft seal is necessary on a - correct answer -Open drive compressor Liquid slugging is - correct answer -Liquid refrigerant in the compressor clearance space The clearance space in reciprocating compressor - correct answer -Has an effect on compressor capacity Which of the following types of air conditioning compressor is most energy-efficient - correct answer - Scroll

Which of the following represent the right order for the functions of a condenser - correct answer -De- superheat, Condenses, Subcools Refrigerant R 134a vapor enters the condenser at 124 psi G, 100°F. it leaves as a liquid from the condenser subcooled 20°F and the pressure will be approximately - correct answer -87 psig There are three basic types of condensers, air-cooled, water-cooled and the _____________ cooled - correct answer -Evaporative 10 pounds of refrigerant passing through a water cooled condenser will lose 20 BTUs of heat per pound. If 10 pounds of water passes through the condenser with an entering temperature of 80°F the temperature of the water leaving the condenser is - correct answer -100°F The heat removed from the refrigerant by the condenser is - correct answer -Both sensible and latent heat. An energy recovery ventilator is - correct answer -an air to air heat exchanger to recover heat When testing the efficiency of an air-cooled condenser, the refrigerant condensing temperature should be approximately ________ higher than the entering air temperature - correct answer -30°F When testing the efficiency of a water-cooled condenser, the refrigerant condensing temperature should be approximately _________ higher than the leaving water temperature - correct answer -10°F The first function condenser must perform is to - correct answer -De-superheat A thermostatic expansion valve is designed to maintain - correct answer -Constant evaporator superheat The automatic expansion valve is designed to maintain - correct answer -Constant evaporator pressure The thermostatic expansion valve has three operating pressures - correct answer -Evaporator pressure, Spring pressure, and Sensor bulb pressure

When mounting a thermostatic expansion valve sensor bulb, which of the following is not true - correct answer -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 - correct answer -Warmer than the evaporator inlet In automatic expansion valve is best suited - correct answer -When the system load remains fairly constant Which of the following is not true of a capillary tube metering device - correct answer -They maintain a constant evaporator temperature A decrease in superheat causes the thermostatic expansion valve to begin to - correct answer -Close A rise in evaporator pressure causes the automatic expansion valve to begin to - correct answer -Close A thermal electric expansion valve is controlled by - correct answer -NTC thermistor In a direct expansion evaporator system, the refrigerant enters the evaporator as - correct answer -A mixture of liquid with some "flash-gas" Which of the following is the most important consideration in the selection of an evaporator coil. Match the coil to the - correct answer -Condensing unit and the latent/sensible loads In the evaporator - correct answer -Latent heat is transferred from the refrigerated space to the refrigerant A liquid line filter-drier should be placed between the - correct answer -Condenser and the Metering device

The only way to minimize flash gas is by - correct answer -Sub-cooling the liquid refrigerant entering the metering device closer to the evaporator temperature A liquid receiver is used to - correct answer -store liquid refrigerant An accumulator is used to - correct answer -Prevent liquid refrigerant from reaching the compressor A sight glass would be normally located - correct answer -in the liquid line before the metering device Bubbles in a sight glass would be an indication of - correct answer -TXV with an excessive superheat setting The oil separator is installed in the - correct answer -Discharge Line Which of the following is true of a solenoid valve in a pump down system - correct answer -Its located before the metering device The purpose of an evaporator pressure regulating valve is to - correct answer -prevent evaporator pressure from falling below a set limit A liquid to suction heat exchanger is often used to - correct answer -increse liquid subcooling The oil pressure safety switch is operated by _________. - correct answer -the difference between crankcase pressure and oil pump pressure A low pressure cut off switch is used to - correct answer -establish a minimum operating pressure in the evaporator A partially iced over evaporator can be caused by - correct answer -an undercharge

_________ can be use for a leak detection with all high-pressure refrigerant - correct answer -Soap bubbles The flow rate of a TXV is used in R 410A systems as compared to R22 systems is - correct answer - Approximately 15% greater When using an electronica leak detector the sensor probe - correct answer -should be moved at approximately 1 inch for every two seconds Moisture in a refrigeration system will cause - correct answer -Compressor failure In order to remove as much moisture as possible from a system - correct answer -triple evacuate the system to 500 microns with a deep vacuum pump what type of gauge is used to measure microns - correct answer -an electronic vacuum gauge Water will vaporize at ________ temperature in a 28 in hg vacuum - correct answer -10°F After a system has been opened and the compressor changed the service technician must - correct answer -Replace the filter dryer, leak check, evacuate, and charge Back seating a two-way service valve results in - correct answer -Open service port with normal system flow The R-410 a compound gauge reads 124 psig in the suction line temperature at the condensing unit is 54°F. What is the operating system superheat - correct answer -12°F When topping off an operating system containing a blended refrigerant - correct answer -introduce the refrigerant as a liquid into the low side using the throttling valve A partially clogged capillary tube can cause - correct answer -A starved evaporator

The r134a0 for a high-pressure gauge reads 146 psig in the liquid line temperature at the condensing unit is 95°F. What is the operating system subcooling - correct answer -15°F An overcharge of refrigerant will cause - correct answer -increased head pressure A customer complains that their air conditioning system is running constantly, but no cooling enough. The suction line is very cold in the compressor is sweating. The most likely cause is - correct answer -a restriction of the return arir or a dirty evaporator A drain trap should be installed on a split system when the - correct answer -Air handler drain is on the negative air side A customer reports that the residential split system had a compressor replaced last week by another service company. Now the unit is not cooling property. 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 - correct answer - Debris from the burned out compressor has clog the dryer What is generally excepted range for evaporator airflow in CFM's per ton of residential air conditioning - correct answer -350 to 450 The temperature rise method for determining airflow is - correct answer -CFM=BTU / (1.08 x delta T) What is the recommended residential indoor relative humidity for summer - correct answer -50% In inefficient compressor is usually indicated by ________ Head pressure and ________ Suction pressure

• correct answer -Higer than normal/ Lower than normal Which of the following is not a symptom of hermetic system that is low on refrigerant - correct answer - High head pressure Frost on the suction line indicates - correct answer -That its temperature is below the dew point and its below 32 degrees

An increase in head pressure causes___refrigerant to flow through a capillary tube - correct answer - More With an automatic expansion valve, an increase in evaporator load will cause the - correct answer - Automatic expansion valve to close When a TEV or capillary tube is used as a metering device a low refrigerant charge will cause - correct answer -Low head pressure What is the maximum operating pressure setting for an acetylene torch - correct answer -15 psig When connecting copper to steal the recommended brazing filler alloy is - correct answer -45% silver alloy Solid contaminants such as sludge and carbon from a severe hermetic compressor motor burn out are best removed - correct answer -By flushing the system and then installing filter dryers in both the liquid and suction lines If the cut off play is removed from the blower assembly how will this affect blower performance - correct answer -It would reduce airflow 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___in order to pressurize the system - correct answer -Inert gas A technician has found an air-conditioning system with a leak in the liquid line. After the line is repaired the system is evacuated in properly recharged. When the system restarted the compressor is noisy and running hot. The most probable cause of the noise is - correct answer -Low oil in the system And air-conditioning system that is oversized can cause - correct answer -Inefficient dehumidification of the condition space

While troubleshooting a residential split system the service technician find slow operating pressures in los system amperage draw. This could be an indication of - correct answer -Low airflow across the evaporator Air or other non-condensable gases in a capillary tube air conditioning system will cause the symptoms - correct answer -High suction pressure and high discharge pressure A refrigerant overcharge in a capillary tube air conditioning system will cause the symptoms - correct answer -High suction pressure and high discharge pressure A compressor that has a broken reed valve will cause the symptoms - correct answer -High suction pressure and low discharge pressure A low refrigerant charge in an air conditioning system will cause the symptoms - correct answer -Low suction pressure and low discharge pressure A TEV sensing bulb which becomes detached from the suction line will cause the symptoms - correct answer -High suction pressure and lower than normal discharge pressure A faulty condenser fan motor on an air conditioning system will cause the symptoms - correct answer - High suction pressure and high discharge pressure A dirty evaporator in an air conditioning system will cause the symptoms - correct answer -Low suction pressure and low discharge pressure