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ESCO Air Conditioning Exam | 100% Correct
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Heat which causes a change in temperature of a substance is called - ✔✔Sensible heat Heat added to a substance without a rise in temperature - ✔✔Latent heat Heat added to the refrigerant in a vapor state after the evaporation process is called - ✔✔Superheat Scroll compressor move refrigerant by - ✔✔Involute Spirals The movement of heat by way of fluid is called - ✔✔Convection The movement of heat by direct contact is - ✔✔Conduction The standard unit for measuring the quantity of heat in a substance is - ✔✔BTUs Refrigerant gives up heat when - ✔✔It condenses Why must refrigerant in the suction line be slightly warmer than the saturation temperature? - ✔✔Prevent liquid slugging of the compressor The state of the refrigerant in the suction line should be - ✔✔Low pressure / Low temperature vapor The state of the refrigerant entering the condenser is - ✔✔High pressure / Highly superheated vapor The evaporator - ✔✔Transfers heat from the refrigerated space to the refrigerant
Which of the following is not a thermodynamic property of refrigerants - ✔✔Flammability The sequential order of steps in the vapor compressions process are - ✔✔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 - ✔✔201 psig Fan airflow pressures are usually measured in - ✔✔Inches of water column 0 pounds per square inch absolute is - ✔✔A pressure which cannot be further reduced 0 pounds per square inch gauge is - ✔✔The same as atmospheric pressure The temperature at which moisture will start to condense from the air is called - ✔✔Dew point temperature A compound pressure gauge measures - ✔✔Pressure and vacuum Mechanical shaft seal is necessary on a - ✔✔Open drive compressor Liquid slugging is - ✔✔Liquid refrigerant in the compressor clearance space The clearance space in reciprocating compressor - ✔✔Has an effect on compressor capacity Which of the following types of air conditioning compressor is most energy-efficient - ✔✔Scroll Which of the following represent the right order for the functions of a condenser - ✔✔De-superheat, Condenses, Subcools
When mounting a thermostatic expansion valve sensor bulb, which of the following is not true - ✔✔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 - ✔✔Warmer than the evaporator inlet In automatic expansion valve is best suited - ✔✔When the system load remains fairly constant Which of the following is not true of a capillary tube metering device - ✔✔They maintain a constant evaporator temperature A decrease in superheat causes the thermostatic expansion valve to begin to - ✔✔Close A rise in evaporator pressure causes the automatic expansion valve to begin to - ✔✔Close A thermal electric expansion valve is controlled by - ✔✔NTC thermistor In a direct expansion evaporator system, the refrigerant enters the evaporator as - ✔✔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 - ✔✔Condensing unit and the latent/sensible loads In the evaporator - ✔✔Latent heat is transferred from the refrigerated space to the refrigerant A liquid line filter-drier should be placed between the - ✔✔Condenser and the Metering device The only way to minimize flash gas is by - ✔✔Sub-cooling the liquid refrigerant entering the metering device closer to the evaporator temperature
A liquid receiver is used to - ✔✔store liquid refrigerant An accumulator is used to - ✔✔Prevent liquid refrigerant from reaching the compressor A sight glass would be normally located - ✔✔in the liquid line before the metering device Bubbles in a sight glass would be an indication of - ✔✔TXV with an excessive superheat setting The oil separator is installed in the - ✔✔Discharge Line Which of the following is true of a solenoid valve in a pump down system - ✔✔Its located before the metering device The purpose of an evaporator pressure regulating valve is to - ✔✔prevent evaporator pressure from falling below a set limit A liquid to suction heat exchanger is often used to - ✔✔increse liquid subcooling The oil pressure safety switch is operated by _________. - ✔✔the difference between crankcase pressure and oil pump pressure A low pressure cut off switch is used to - ✔✔establish a minimum operating pressure in the evaporator A partially iced over evaporator can be caused by - ✔✔an undercharge _________ can be use for a leak detection with all high-pressure refrigerant - ✔✔Soap bubbles The flow rate of a TXV is used in R 410A systems as compared to R22 systems is - ✔✔Approximately 15% greater
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 - ✔✔a restriction of the return arir or a dirty evaporator A drain trap should be installed on a split system when the - ✔✔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 - ✔✔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 - ✔✔350 to 450 The temperature rise method for determining airflow is - ✔✔CFM=BTU / (1.08 x delta T) What is the recommended residential indoor relative humidity for summer - ✔✔50% In inefficient compressor is usually indicated by ________ Head pressure and ________ Suction pressure
- ✔✔Higer than normal/ Lower than normal Which of the following is not a symptom of hermetic system that is low on refrigerant - ✔✔High head pressure Frost on the suction line indicates - ✔✔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 - ✔✔More
With an automatic expansion valve, an increase in evaporator load will cause the - ✔✔Automatic expansion valve to close When a TEV or capillary tube is used as a metering device a low refrigerant charge will cause - ✔✔Low head pressure What is the maximum operating pressure setting for an acetylene torch - ✔✔15 psig When connecting copper to steal the recommended brazing filler alloy is - ✔✔45% silver alloy Solid contaminants such as sludge and carbon from a severe hermetic compressor motor burn out are best removed - ✔✔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 - ✔✔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 - ✔✔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 - ✔✔Low oil in the system And air-conditioning system that is oversized can cause - ✔✔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 - ✔✔Low airflow across the evaporator
