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

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ESCO Air Conditioning Exam with correct

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Heat which causes a change in temperature of a substance is called - ** VERIFIED ANSWERS ** ✔✔ Sensible heat Heat added to a substance without a rise in temperature - ** VERIFIED ANSWERS ** ✔✔ Latent heat Heat added to the refrigerant in a vapor state after the evaporation process is called - ** VERIFIED ANSWERS ** ✔✔ Superheat Scroll compressor move refrigerant by - ** VERIFIED ANSWERS ** ✔✔ Involute Spirals The movement of heat by way of fluid is called - ** VERIFIED ANSWERS ** ✔✔ Convection The movement of heat by direct contact is - ** VERIFIED ANSWERS ** ✔✔ Conduction The standard unit for measuring the quantity of heat in a substance is - ** VERIFIED ANSWERS ** ✔✔ BTUs Refrigerant gives up heat when - ** VERIFIED ANSWERS ** ✔✔ It condenses Why must refrigerant in the suction line be slightly warmer than the saturation temperature? - ** VERIFIED ANSWERS ** ✔✔ Prevent liquid slugging of the compressor

The state of the refrigerant in the suction line should be - ** VERIFIED ANSWERS ** ✔✔ Low pressure / Low temperature vapor The state of the refrigerant entering the condenser is - ** VERIFIED ANSWERS ** ✔✔ High pressure / Highly superheated vapor The evaporator - ** VERIFIED ANSWERS ** ✔✔ Transfers heat from the refrigerated space to the refrigerant Which of the following is not a thermodynamic property of refrigerants - ** VERIFIED ANSWERS ** ✔✔ Flammability The sequential order of steps in the vapor compressions process are - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ 201 psig Fan airflow pressures are usually measured in - ** VERIFIED ANSWERS ** ✔✔ Inches of water column 0 pounds per square inch absolute is - ** VERIFIED ANSWERS ** ✔✔ A pressure which cannot be further reduced 0 pounds per square inch gauge is - ** VERIFIED ANSWERS ** ✔✔ The same as atmospheric pressure The temperature at which moisture will start to condense from the air is called - ** VERIFIED ANSWERS ** ✔✔ Dew point temperature A compound pressure gauge measures - ** VERIFIED ANSWERS ** ✔✔ Pressure and vacuum

Mechanical shaft seal is necessary on a - ** VERIFIED ANSWERS ** ✔✔ Open drive compressor Liquid slugging is - ** VERIFIED ANSWERS ** ✔✔ Liquid refrigerant in the compressor clearance space The clearance space in reciprocating compressor - ** VERIFIED ANSWERS ** ✔✔ Has an effect on compressor capacity Which of the following types of air conditioning compressor is most energy- efficient - ** VERIFIED ANSWERS ** ✔✔ Scroll Which of the following represent the right order for the functions of a condenser - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ 87 psig There are three basic types of condensers, air-cooled, water-cooled and the _____________ cooled - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ 100 °F The heat removed from the refrigerant by the condenser is - ** VERIFIED ANSWERS ** ✔✔ Both sensible and latent heat. An energy recovery ventilator is - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ 30 °F When testing the efficiency of a water-cooled condenser, the refrigerant condensing temperature should be approximately _________ higher than the leaving water temperature - ** VERIFIED ANSWERS ** ✔✔ 10 °F The first function condenser must perform is to - ** VERIFIED ANSWERS ** ✔✔ De- superheat A thermostatic expansion valve is designed to maintain - ** VERIFIED ANSWERS ** ✔✔ Constant evaporator superheat The automatic expansion valve is designed to maintain - ** VERIFIED ANSWERS ** ✔✔ Constant evaporator pressure The thermostatic expansion valve has three operating pressures - ** VERIFIED ANSWERS ** ✔✔ Evaporator pressure, Spring pressure, and Sensor bulb pressure When mounting a thermostatic expansion valve sensor bulb, which of the following is not true - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ Warmer than the evaporator inlet In automatic expansion valve is best suited - ** VERIFIED ANSWERS ** ✔✔ When the system load remains fairly constant Which of the following is not true of a capillary tube metering device - ** VERIFIED ANSWERS ** ✔✔ They maintain a constant evaporator temperature

A decrease in superheat causes the thermostatic expansion valve to begin to - ** VERIFIED ANSWERS ** ✔✔ Close A rise in evaporator pressure causes the automatic expansion valve to begin to - ** VERIFIED ANSWERS ** ✔✔ Close A thermal electric expansion valve is controlled by - ** VERIFIED ANSWERS ** ✔✔ NTC thermistor In a direct expansion evaporator system, the refrigerant enters the evaporator as - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ Condensing unit and the latent/sensible loads In the evaporator - ** VERIFIED ANSWERS ** ✔✔ Latent heat is transferred from the refrigerated space to the refrigerant A liquid line filter-drier should be placed between the - ** VERIFIED ANSWERS ** ✔✔ Condenser and the Metering device The only way to minimize flash gas is by - ** VERIFIED ANSWERS ** ✔✔ Sub- cooling the liquid refrigerant entering the metering device closer to the evaporator temperature A liquid receiver is used to - ** VERIFIED ANSWERS ** ✔✔ store liquid refrigerant An accumulator is used to - ** VERIFIED ANSWERS ** ✔✔ Prevent liquid refrigerant from reaching the compressor A sight glass would be normally located - ** VERIFIED ANSWERS ** ✔✔ in the liquid line before the metering device

Bubbles in a sight glass would be an indication of - ** VERIFIED ANSWERS ** ✔✔ TXV with an excessive superheat setting The oil separator is installed in the - ** VERIFIED ANSWERS ** ✔✔ Discharge Line Which of the following is true of a solenoid valve in a pump down system - ** VERIFIED ANSWERS ** ✔✔ Its located before the metering device The purpose of an evaporator pressure regulating valve is to - ** VERIFIED ANSWERS ** ✔✔ prevent evaporator pressure from falling below a set limit A liquid to suction heat exchanger is often used to - ** VERIFIED ANSWERS ** ✔✔ increse liquid subcooling The oil pressure safety switch is operated by _________. - ** VERIFIED ANSWERS ** ✔✔ the difference between crankcase pressure and oil pump pressure A low pressure cut off switch is used to - ** VERIFIED ANSWERS ** ✔✔ establish a minimum operating pressure in the evaporator A partially iced over evaporator can be caused by - ** VERIFIED ANSWERS ** ✔✔ an undercharge _________ can be use for a leak detection with all high-pressure refrigerant - ** VERIFIED ANSWERS ** ✔✔ Soap bubbles The flow rate of a TXV is used in R 410A systems as compared to R22 systems is - ** VERIFIED ANSWERS ** ✔✔ Approximately 15% greater When using an electronica leak detector the sensor probe - ** VERIFIED ANSWERS ** ✔✔ should be moved at approximately 1 inch for every two seconds

Moisture in a refrigeration system will cause - ** VERIFIED ANSWERS ** ✔✔ Compressor failure In order to remove as much moisture as possible from a system - ** VERIFIED ANSWERS ** ✔✔ triple evacuate the system to 500 microns with a deep vacuum pump what type of gauge is used to measure microns - ** VERIFIED ANSWERS ** ✔✔ an electronic vacuum gauge Water will vaporize at ________ temperature in a 28 in hg vacuum - ** VERIFIED ANSWERS ** ✔✔ 10 °F After a system has been opened and the compressor changed the service technician must - ** VERIFIED ANSWERS ** ✔✔ Replace the filter dryer, leak check, evacuate, and charge Back seating a two-way service valve results in - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ 12 °F When topping off an operating system containing a blended refrigerant - ** VERIFIED ANSWERS ** ✔✔ introduce the refrigerant as a liquid into the low side using the throttling valve A partially clogged capillary tube can cause - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ 15 °F An overcharge of refrigerant will cause - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ a restriction of the return arir or a dirty evaporator A drain trap should be installed on a split system when the - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ 350 to 450 The temperature rise method for determining airflow is - ** VERIFIED ANSWERS ** ✔✔ CFM=BTU / (1.08 x delta T) What is the recommended residential indoor relative humidity for summer - ** VERIFIED ANSWERS ** ✔✔ 50% In inefficient compressor is usually indicated by ________ Head pressure and ________ Suction pressure - ** VERIFIED ANSWERS ** ✔✔ Higer than normal/ Lower than normal

Which of the following is not a symptom of hermetic system that is low on refrigerant - ** VERIFIED ANSWERS ** ✔✔ High head pressure Frost on the suction line indicates - ** VERIFIED ANSWERS ** ✔✔ 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

• ** VERIFIED ANSWERS ** ✔✔ More With an automatic expansion valve, an increase in evaporator load will cause the - ** VERIFIED ANSWERS ** ✔✔ Automatic expansion valve to close When a TEV or capillary tube is used as a metering device a low refrigerant charge will cause - ** VERIFIED ANSWERS ** ✔✔ Low head pressure What is the maximum operating pressure setting for an acetylene torch - ** VERIFIED ANSWERS ** ✔✔ 15 psig When connecting copper to steal the recommended brazing filler alloy is - ** VERIFIED ANSWERS ** ✔✔ 45% silver alloy Solid contaminants such as sludge and carbon from a severe hermetic compressor motor burn out are best removed - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ Low oil in the system And air-conditioning system that is oversized can cause - ** VERIFIED ANSWERS ** ✔✔ 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 - ** VERIFIED ANSWERS ** ✔✔ Low airflow across the evaporator Air or other non-condensable gases in a capillary tube air conditioning system will cause the symptoms - ** VERIFIED ANSWERS ** ✔✔ High suction pressure and high discharge pressure A refrigerant overcharge in a capillary tube air conditioning system will cause the symptoms - ** VERIFIED ANSWERS ** ✔✔ High suction pressure and high discharge pressure A compressor that has a broken reed valve will cause the symptoms - ** VERIFIED ANSWERS ** ✔✔ High suction pressure and low discharge pressure A low refrigerant charge in an air conditioning system will cause the symptoms - ** VERIFIED ANSWERS ** ✔✔ Low suction pressure and low discharge pressure A TEV sensing bulb which becomes detached from the suction line will cause the symptoms - ** VERIFIED ANSWERS ** ✔✔ High suction pressure and lower than normal discharge pressure A faulty condenser fan motor on an air conditioning system will cause the symptoms - ** VERIFIED ANSWERS ** ✔✔ High suction pressure and high discharge pressure

A dirty evaporator in an air conditioning system will cause the symptoms - ** VERIFIED ANSWERS ** ✔✔ Low suction pressure and low discharge pressure