NATE A/C Exam #1 questions and correct answers latest 2023

NATE A/C Exam #1 questions and correct answers latest 2023Low airflow over a residential split system air conditioning evaporator can cause A: Liquid flood-back to the compressor B: A decrease in compression ratio C: An increase in suction line superheat D: Oil logging in the evaporator A: Liquid flood-back to the compressor Which of the following is the correct sequence of work? A: Attach gauge manifold, recover refrigerant, replace filter core, evacuate the system, recharge the system. B: Recover refrigerant, evacuate the system, replace filter core, recharge the system. C: Attach gauge manifold, evacuate the system, replace filter core, recover refrigerant, recharge the system. D: Attach gauge manifold, recharge the system, evacuate the system, replace filter core. A: Attach gauge manifold, recover refrigerant, replace filter core, evacuate the system, recharge the system. As the pressure on a liquid is increased, the vaporization temperature of the liquid A: Decreases B: Increases C: Remains unchanged D: Varies B: Increases An oil separator must be mounted A: Level B: Below the compressor crankcase C: Above the compressor crankcase D: In the suction line A: Level Which of the following metering devices controls evaporator pressure? A: Thermostatic expansion valve B: Fixed orifice C: Low side float D: None of these D: None of these An automatic expansion valve controls evaporator pressure. The purpose of the external equalizer on a thermostatic expansion valve is A: To equalize evaporator pressure drop with respect to the TEV B: To equalize the evaporator pressure drop C: To help prevent liquid floodback D: To allow the high side pressure to equalize to the low side when the compressor cycles off A: To equalize evaporator pressure drop with respect to the TEV The higher the MERV rating of a filter-drier, the A: More efficient the drier at absorbing moisture B: Less efficient the drier at absorbing moisture C: Smaller the particles the filter can entrap D: MERV does not apply to filter-driers D: MERV does not apply to filter-driers Minimum Efficiency Reporting Value - MERV ratings are used to rate the ability of an air conditioning filter to remove dust from the air as it passes through the filter. MERV is a standard used to measure the overall efficiency of a filter. Higher MERV ratings mean fewer dust particles and other airborne contaminants pass through the filter. Filters with a merv rating of 9 to 12 are used in commercial and industrial applications and will stop particles in the 1 to 3 micron range. These filters are a great choice for home owners who want the best dust control possible. When using filters with Merv 9 ratings and above it is important to clean or replace them when recommended by the manufacturer because they will have a negative effect on air flow when they become dirty. This can lead to performance problems and decreased operating efficiency. The most efficient filters have merv ratings of 13 to 16 and will stop particles as small as .3 microns. These filters are used in hospitals and other super clean environments. Zeolite is used with A: Refrigerant filter-driers B: HEPA filters C: Pipe threads D: Solder A: Refrigerant filter-driers Vacuum pressures are measured in A: Microns B: Millimeters of mercury C: Inches of mercury D: All of the above D: All of the above The number 25,400 relates to A: Microns/inch B: Btu/ton C: Cfm/hp D: Cfm/ton A: Microns/inch The general rule of thumb for airflow is A: 400 cfm/ton B: 400 cfm/hp C: 6 cfm/sq D: 144 cfm/cu A: 400 cfm/ton A double suction riser is used to A: Help improve refrigerant return B: Allow the compressor to pump at a greater capacity C: Decrease suction line resistance D: Improve oil return as system capacity changes D: Improve oil return as system capacity changes A service technician measures a return air temperature of 80 degrees and a supply air temperature of 55 degrees. What, if anything, may be wrong with this air residential split system air conditioning unit? A: Low on refrigerant charge B: Low on evaporator airflow C: Refrigerant overcharge D: There is probably nothing wrong with the system B: Low on evaporator airflow The normal compression ratio for a typical comfort air conditioning application should be in the range of A: 1 to 2 B: 1.5 to 2.25 C: 2 to 3 D: 2.75 to 3.75 D: 2.75 to 3.75 Compression rate = discharge pressure (psia) / suction pressure (psia) All else being normal, if a system shows a high lowside superheat with high condenser subcooling, what is most likely the problem? A: Refrigerant overcharge B: Refrigerant undercharge C: A partial refrigerant restriction D: There is probably no problem C: A partial refrigerant restriction All else being normal, if a system shows a low lowside superheat with high condenser subcooling, what is most likely the problem? A: Refrigerant overcharge B: Refrigerant undercharge C: A partial restriction D: There is probably no problem A: Refrigerant overcharge All else being normal, if a system shows a high lowside superheat with low condenser subcooling, what is most likely the problem? A: Refrigerant overcharge B: Refrigerant undercharge C: A partial restriction D: There is probably no problem B: Refrigerant undercharge A grille equipped with a damper control is called A: A vane B: A register C: A louver D: A damper B: A register A pressure relief valve is A: Direct pressure acting B: Remote pressure activated C: Manually operated D: Reverse pressure acting A: Direct pressure acting A parallel compressor system in which both the crankcase oil level and the refrigerant gas pressure are equalized is a A: Double pipe crankcase equalizer system B: Single pipe crankcase equalizer system C: External equalizer oil system D: Crankcase hot gas oil equalizer A: Double pipe crankcase equalizer system In a direct expansion chiller used on air conditioning applications, the refrigerant is on what side of the tubes? A: Around the diverter B: In the tubes C: Surrounding the tubes D: On both sides B: In the tubes The total minimum open area for air to flow through on a supply air register is called A: Free area B: Open area C: Core area D: Drop area A: Free area Which type of copper tubing has the thickest wall? A: Type L B: Type K C: Type M D: Type DWV B: Type K Types K, L, M, DWV and Medical Gas tube are designated by ASTM standard sizes, with the actual outside diameter always 1/8-inch larger than the standard size designation. Each type represents a series of sizes with different wall thicknesses. Type K tube has thicker walls than Type L tube, and Type L walls are thicker than Type M, for any given diameter. All inside diameters depend on tube size and wall thickness. Copper tube for air-conditioning and refrigeration field service (ACR) is designated by actual outside diameter. What is the gross weight of a refrigerant cylinder? A: The weight of the cylinder minus the refrigerant B: The weight of the cylinder plus the weight of the refrigerant C: The weight of cylinder's refrigerant capacity D: The weight of the cylinder and the box around the cylinder B: The weight of the cylinder plus the weight of the refrigerant What does an anemometer measure? A: Feet B: Feet per minute C: Cubic feet per minute D: Vacuum pressure in microns A: Feet The anemometer only measures feet while the operator uses a stop watch or second hand on a watch. This is a typical "trick" question to watch for The term "induced draft" most likely refers to A: A compressor B: A type of control C: A type of cooling tower D: A type of test instrument C: A type of cooling tower What fitting should be used to connect 1⁄4" copper tubing to a 1⁄4" internal pipe thread opening on a compressor crankcase? A: A union B: A half union C: A tee D: A street ell B: A half union Which of the following compressors has the fewest moving parts? A: Rotating vane rotary B: Fixed vane rotary C: Scroll D: Reciprocating C: Scroll A hot liquid line with a low to normal high side pressure is an indication of A: An overcharged system B: An undercharged system C: Air in the system D: A restricted filterdrier B: An undercharged system Air and water are directed counterflow so as to A: Average the flow rate B: Gain the greatest amount of heat transfer C: Reach the lowest apparatus dew point D: Control the humidity B: Gain the greatest amount of heat transfer Which of the following applications is not a mechanical cooling system? A: Cascade system B: Reciprocating compression system C: Evaporative cooling D: Centrifugal compression system C: Evaporative cooling A compressor is short cycling. Which of the following would not be the cause? A: Low pressure controller differential set too close B: Automatic reset high pressure control differential set too close C: Low refrigerant charge D: Leaking compressor suction valve D: Leaking compressor suction valve