NATE Exam: AC & HP Questions With 100% Correct Answers | Updated & Verified 2023, Exams of Advanced Education

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NATE Exam: AC & HP Questions With

100% Correct Answers | Updated &

Verified 2023

a (Centrifugal) - Correct Answer-Which of the following compressors are considered a dynamic compressor? a. Centrifugal b. Reciprocating d. Rotary c. Scroll b (Superheated vapor / sub cooled liquid) - Correct Answer-What is the condition of the refrigerant as it enters and leaves the condensing coil of a typical light commercial HVAC system? a. Vapor / liquid b. Superheated vapor / sub cooled liquid c. Saturated vapor / saturated liquid d. Hot gas / cool liquid b (Thermal expansion valve) - Correct Answer-Which one of the following are considered the best metering device of the industry? a. Capillary tube b. Thermal expansion valve d. Constant pressure expansion valve c. Electronic expansion valve b (POE. Newer refrigerant systems today using R-134a and R-410a use a synthetic Polyester POE oil. Older refrigeration systems using R-12, R-502, and R-22 use a mineral based oil.) - Correct Answer-Which of the following types of refrigeration oil would you expect to find in a typical commercial R-134a freezer? a. Mineral 150 b. POE c. AB d. Mineral 300 b (Compressor discharge / compressor suction) - Correct Answer-Where does the small single port tube and the larger middle port tube go on a typical residential or light commercial reversing valve?

a. Inlet outdoor coil / inlet indoor coil b. Compressor discharge / compressor suction c. Compressor suction / compressor discharge c. Outlet indoor coil / outlet outdoor coil d (restricted liquid line filter/drier) - Correct Answer-If you were working on a 3.5 ton split system, with a 125,000 BTH/H horizontal furnace, and you had a low suction pressure, low discharge pressure, high superheat, and high subcooling, what is wrong with the system? a. low refrigerant charge b. overcharged system c. overfeeding metering device d. restricted liquid line filter/drier c (overfeeding metering device) - Correct Answer-If you were working on a 3.5 ton split system, with a 125,000 BTU/H horizontal furnace, and you had high suction pressure, low discharge pressure, low superheat, and low subcooling, what is wrong with the system? a. low refrigerant charge b. overcharged system c. overfeeding metering device d. restricted liquid line filter/drier a (weak compressor valves) - Correct Answer-If you were working on a 3.5 ton split system, with a 125,000 BTU/H horizontal furnace, and you had high suction pressure, low discharge pressure, high superheat, and low subcooling, what is wrong with the system? a. weak compressor valves b. stuck reversing valve c. bad indoor check valve d. bad outdoor check valve b (overcharge system) - Correct Answer-If you were working on a 3.5 ton split system, with a 125,000 BTU/H horizontal furnace, and you had high suction pressure, high discharge pressure, low superheat, and high subcooling, what is wrong with the system? a. low refrigerant charge b. overcharged system c. overfeeding metering device d. restricted liquid line filter/drier

d (to compensate charge in the cooling cycle) - Correct Answer-You are working on a heat pump package unit and come across a charge compensator, what is it used for? a. to compensate for a low refrigerant charge b. to compensate for an overcharged system c. to compensate charge in the heating cycle d. to compensate charge in the cooling cycle b (three connections, between the reversing valve and outdoor coil, and the liquid line) - Correct Answer-You are working on a heat pump package unit with a charge compensator, how is the charge compensator connected to the refrigeration system? a. two connection, both the suction and discharge lines between the compressor and reversing valve b. three connections, between the reversing valve and outdoor coil, and the liquid line c. four connections, between the reversing valve, outdoor coil, and upstream and downstream of the metering device. d. four connections, between the reversing valve, indoor coil, and upstream and downstream of the metering device. b (constant enthalpy valve) - Correct Answer-A thermal expansion valve is also considered what type of valve? a. constant entropy valve b. constant enthalpy valve c. constant temperature valve d. constant pressure valve d (electronic air cleaner) - Correct Answer-Which of the following is an optional accessory in a split residential HVAC system? a. thermostat b. line set c. condenser fan d. electronic air cleaner d (modulates to maintain suction superheat) - Correct Answer-A thermostatic expansion valve? a. is a fixed orifice b. modulates to maintain suction pressure c. modulates to maintain suction temperature d. modulates to maintain suction superheat

c (a heat pump system) - Correct Answer-A suction line accumulator would most likely be installed in? a. an air conditioning system b. a fan coil unit c. a heat pump system d. a gas furnace a (0.5 inches water gauge) - Correct Answer-Most residential equipment can deliver rated air flow against an external static pressure of? a. 0.5 inches water gauge b. 0.5 inches mercury gauge c. 0.5 inches PSIG d. 0.5 inches of PSIA c (protect the compressor from liquid refrigerant) - Correct Answer-A suction line accumulator is used to do what? a. store liquid refrigerant during the off cycle b. store liquid refrigerant during the on cycle c. protect the compressor from liquid refrigerant d. protect the reversing valve a (store liquid refrigerant during the off cycle) - Correct Answer-A liquid line receiver is used to do what? a. store liquid refrigerant during the off cycle b. protect the compressor from liquid refrigerant c. protect the reversing valve d. accumulate debris from the system c (condenser fan control) - Correct Answer-Many metering devices require a minimum pressure difference to operate, this can be maintained by which of the following system components? a. a crankcase heater b. evaporator fan control c. condenser fan control d. compressor capacity control b (lubricates compressor) - Correct Answer-Refrigeration oil in a refrigerant system a. helps circulate the refrigerant b. lubricates the compressor

c. improves the evaporator heat transfer d. evaporates and condenses with the refrigerant b (outdoor fan) - Correct Answer-What component is never energized in the heat pump defrost mode? a. indoor fan b. outdoor fan c. reversing valve d. crankcase heater b (an indoor coil and an outdoor coil) - Correct Answer-An air to air heat pump has a. an indoor coil and a condenser coil b. an indoor coil and an outdoor coil c. an electric heater and a receiver d. a reversing valve and an inducer fan d (low pressure sensing switch) - Correct Answer-Heat pumps typically do not have a a. suction line accumulator b. reversing valve c. compressor crankcase heater d. low pressure sensing switch c (it may not dehumidify the space) - Correct Answer-If an air conditioner system that is too large is installed in a residence a. it will not cool the space b. it will over cool the space c. it may not dehumidify the space d. it may over dehumidify the space a (the suction pressure may be too low) - Correct Answer-If an energized cool reversing valve sticks in mid position a. the suction pressure may be too low b. the discharge pressure may be too high c. the system may be overcharged d. the system may be in defrost a (work performed divided by energy used) - Correct Answer-COP refers to a. work performed divided by energy used b. energy used divided by work performed c. heating capacity divided by cooling capacity

d. cooling capacity divided by heating capacity d (dust) - Correct Answer-An electronic air cleaner is designed to remove a. ozone b. odors c. carbon monoxide d. dust c (a supply plenum) - Correct Answer-A chamber for distributing air in an HVAC system is a. a diffuser b. an air duct c. a supply plenum d. a trunk or branch d (a square corner square 90) - Correct Answer-All of the following air duct & fittings have the same girth measurement, which has the highest pressure drop a. a one-foot section of straight duct b. a long-radius round 90 c. a short-radius round 90 d. a square corner square 90 a (in the supply air) - Correct Answer-Registers and diffusers are normally a. in the supply air b. in the return air c. in either the supply or return air d. normally mounted at high level a (1,000 - 2,000 FPM) - Correct Answer-Low velocity air flow HVAC systems have airflow in what range? a. 1,000 - 2,000 FPM b. 2,000 - 3,000 FPM c. 3,000 - 4,000 FPM d. 4,000 - 5,000 FPM d (using several thousand volts DC) - Correct Answer-Electronic air cleaners add an electrical charge to dirt particles in the air a. using 230V AC d. using 230V DC c. using several thousand volts AC

d. using several thousand volts DC b (Mineral oil) - Correct Answer-CFC and HCFC refrigerants normally use a. AKB oil b. Mineral oil c. PAG oil d. POE oil b (230/1/60) - Correct Answer-Residential fan coils typically require what power? a. 115/1/ b. 230/1/ c. 230/3/ d. 460/3/ b (10%) - Correct Answer-Most HVAC electrical components have a voltage tolerance of what percent? a. 5% b. 10% c. 15% d. 20% a (a fixed orifice) - Correct Answer-Suction superheat is used to charge a system with what type of metering device? a. fixed orifice b. an automatic expansion valve c. a thermostatic expansion valve d. a high side float b (use the piston from the condensing unit) - Correct Answer-If a fan coil arrives with one size piston, and the condensing unit arrives with a different size piston, which one should you use? a. use the piston from the fan coil b. use the piston from the condensing unit c. always use the larger size piston d. always use the smaller size piston b (an ammeter) - Correct Answer-When a compressor is energized you would measure its work load with what test instrument? a. a voltmeter b. an ammeter

c. an ohmmeter d. a megohmmeter c (open at this time) - Correct Answer-When a voltmeter shows 230V across the contacts of a switch, the switch is? a. normally open b. normally closed c. open at this time d. closed at this time b (3/8" OD tubing) - Correct Answer-Most residential liquid lines: a. should be insulated if they go thru the attic b. are 3/8" OD tubing c. transmit noise and vibration d. use flare fittings a (which may be transmitted to a building) - Correct Answer-Refrigerant leaves a residential or light commercial HVAC unit's compressor in pulses: a. which may be transmitted to a building b. which require a muffler c. except for scroll compressors d. which affect reversing valve operation b (all refrigerant components are already assembled and sealed) - Correct Answer-A common advantage of a one-piece packaged air conditioner is: a. that it is smaller than a split system b. all refrigerant components are already assembled and sealed c. less expensive than a split system d. that the air ducts can be made smaller a (to avoid condensing air re-circulation) - Correct Answer-A condensing unit should be installed: a. to avoid condensing unit air re-circulation b. close to the structure it is servicing c. above the air handler if possible d. in the shade if possible a (be sloped toward the drain) - Correct Answer-A commercial condensate drain line should: a. be sloped toward the drain

b. always have an external trap c. be at least 1 inch in diameter d. be made of copper c (a thermostatic expansion valve) - Correct Answer-Condensing unit sub-cooling is used to charge a system with what type of metering device? a. a fixed orifice b. replaceable pistons c. a thermostatic expansion valve d. a high side float c (voltage to the holding coil is low) - Correct Answer-A contactor may make an excessive noise when: a. voltage to the contacts are low b. amperage to the contacts are high c. voltage to the holding coil is low d. amperage to the holding coil is high c (a bad compressor run capacitor) - Correct Answer-If a compressor motor hums, and trips a few seconds later, the root cause may be: a. a bad crankcase heater b. a compressor internal overload c. a bad compressor run capacitor d. an automatic high pressure switch b (it is undercharged) - Correct Answer-A system with a fixed rate orifice should have 15°F suction superheat, but has 25°F suction superheat, what does that mean? a. it is overcharged b. it is undercharged c. it is correctly charged d. it is running satisfactory c (low indoor airflow) - Correct Answer-Low suction pressure and low suction superheat may be caused by: a. refrigerant undercharge b. refrigerant overcharge c. low indoor airflow d. high indoor airflow a (refrigerant undercharge) - Correct Answer-Low suction pressure and high suction superheat may be caused by:

a. refrigerant undercharge b. refrigerant overcharge c. low indoor airflow d. high indoor airflow b (refrigerant overcharge) - Correct Answer-High suction pressure and low suction superheat may be caused by: a. refrigerant undercharge b. refrigerant overcharge c. low indoor airflow d. high indoor airflow d (high indoor airflow) - Correct Answer-High suction pressure and high suction superheat may be caused by: a. refrigerant undercharge b. refrigerant overcharge c. low indoor airflow d. high indoor airflow c (indoor fan) - Correct Answer-If a high pressure switch trips on a heat pump while in the heating mode, check the: a. evaporator fan b. condenser fan c. indoor fan d. outdoor fan c (indoor fan) - Correct Answer-If a low pressure switch trips on a heat pump while in the cooling mode, check the: a. evaporator fan b. condenser fan c. indoor fan d. outdoor fan a (high superheat and low sub-cooling) - Correct Answer-If a fixed orifice HVAC system is undercharged, you should expect: a. high superheat and low sub-cooling b. high superheat and high sub-cooling c. low superheat and low sub-cooling d. low superheat and high sub-cooling

d (decreases off-cycle migration to compressor) - Correct Answer-A compressor's crankcase heater: a. prevents refrigerant flood back b. prevents the oil from getting too thick c. prevents liquid migration to the compressor d. decreases off-cycle migration to compressor d (ductwork problems) - Correct Answer-If a grille or register is noisy, suspect: a. air flow is too low b. air flow is too hot c. bent or broken damper d. ductwork problems d (The lowest OSA temperature it can efficienctly heat the structure) - Correct Answer- The balance point of a heat pump system is: a. The lowest OSA temperature it can operate at b. The hightest OSA temperature it can operate at c. The highest OSA temperature it can efficiently heat the structure d. The lowest OSA temperature it can efficiently heat the structure