NATE Air Conditioning Service Certification Practice Test

These questions are part of the practice quiz. Start practicing

• When a residential supply diffuser is noisy due to a loose vane, what should be done?
• What are the symptoms of a failing expansion valve?
• What does the acronym "NATE" stand for in the context of air conditioning certification?
• What does a "MERV" rating indicate in air filters?
• The purpose of a sequencer in an auxiliary 20 kW electric heater is to energize:
• What could a constant high discharge temperature indicate in an air conditioning system?
• Other than using a two-stage compressor, what is another method for capacity control?
• What is the role of the expansion valve in an air conditioning system?
• What is the function of a capacitor in an air conditioning system?
• In an economizer system, the enthalpy control measures which of the following?
• What would cause a voltage reading across a closed contact in a 24V control circuit?
• Why is mineral oil preferred for use with R-22 compressors?
• Which substance could create a dangerous condition when checking a refrigeration system for leaks?
• The following conditions exist in a circuit that supplies power to three phase parallel loads. What will be the total current in the circuit when operating?
• What factors should a technician determine when replacing a contactor?
• Why is it important to check the ductwork in an HVAC system?
• In a heat pump system, when is the reversing valve typically engaged?
• What is the primary function of an expansion valve in a refrigeration system?
• How should a technician evaluate the circuitry when the wiring diagram is missing?
• On a residential no cooling call, what is typically the first check that should be performed?
• What precautions need to be taken with packaged AC systems that have ductwork installed outside?
• Where are most safety controls wired?
• In which part of the cycle does the refrigerant absorb heat?
• What is the maximum acceptable supply voltage tolerance for a 120 V circuit?
• How does a programmable thermostat differ from a standard thermostat?
• What is the purpose of a crankcase heater in refrigeration systems?
• What is the main purpose of using flux when soldering?
• What does an airflow measure of 1550 CFM on a 3-ton unit installation indicate?
• What is the purpose of an evaporator coil in an air conditioning system?
• What does the minimum circuit ampacity (MCA) listed on the dataplate determine?
• What rapid suction pressure rise indicates when the power is shut off in a reciprocating compressor system?
• Which of the following can cause lower than normal suction pressure?
• What should be done to repair a noisy metal supply register with bent vanes?
• Which of the following is an essential part of troubleshooting refrigerant circuits?
• What is the rpm of a blower wheel in a direct drive blower compared to the blower motor?
• What effect does refrigerant oil in a hose have when using a manifold gauge set?
• What is a common cause of ice build-up on the evaporator coil?
• What component is used to reduce sound transmission and prevent water leaks on a rooftop air conditioner installation?
• What is the primary purpose of a compressor contactor?
• What is the standard factory setting for the indoor fan on most air conditioning units?
• How does a thermostat control the temperature in an air conditioning system?
• Which tool is best for measuring AC voltage in HVAC systems?
• When replacing a failed R-22 condensing unit with a new R-410A condensing unit, what must happen to the existing R-22 evaporator?
• What is a common effect of low refrigerant levels in an air conditioning system?
• According to fire protection codes, when should fire dampers be used?
• When an air conditioner with a thermostatic expansion valve is overcharged, how should the excess charge be removed?
• A delay on make relay delays the load from which of the following?
• In terms of energy efficiency, what does a higher SEER rating indicate?
• What is the standard refrigerant used in modern air conditioning systems?
• What safety precaution should be taken when handling refrigerants?
• The slab of a packaged air conditioner at grade level should be located:
• What is one function of the condenser in an air conditioning system?
• What is the total refrigerant charge for a system supplied with 5 pounds 10 ounces for a 15-foot line set, but has a 25-foot line set requiring additional refrigerant?
• Why might electromechanical type thermostats need connections to both the hot and common sides of the transformer?
• Which pressure does a high pressure limit control monitor in a compressor?
• In HVAC systems, what is the purpose of a TXV (Thermal Expansion Valve)?
• If a duct measures 36 in. x 24 in. and has an average velocity of 600 fpm, what is the CFM?
• Which component is primarily responsible for compressing refrigerant in a system?
• What effect does insufficient voltage have on a solenoid valve?
• In a simple refrigeration system, where does the refrigerant boil?
• What is the purpose of the grounding conductor?
• When should the refrigerant levels be checked in a system?
• What is indicated by a test of the compressor oil after a burnout?
• What can occur if a refrigerant line is improperly insulated?
• What type of refrigerant is known for being environmentally friendly and non-ozone depleting?
• What could cause a customer to complain that their home feels damp or "sticky"?
• Which instrument is used to measure refrigerant pressures in an HVAC system?
• What refrigerant is being phased out due to environmental concerns?
• Return air leakage in a hot attic will generally:
• What type of lubricating oil is primarily used with R-22 air conditioning compressors?
• When a split system air conditioner has a counterflow air handler, what are the best locations for return air grilles?
• What happens when a disc-type, close-on-rise pressure control's setpoint drifts lower?
• How do two ninety degree short radius elbows affect an air conditioner suction line?
• When troubleshooting an energized electrical circuit on an electric heat section, if 244 volts is measured across the element at points A and B but no amperage is measured, what is the likely problem?
• When performing maintenance on a split AC system, why is checking for refrigerant leaks crucial?
• Which component's operation could lead to low cooling performance if it's malfunctioning?
• A technician finds a R-410A system with a suction pressure of 105 psi and suction line temperature of 75°F. If the recommended superheat is 20°F, what does this indicate about the system?
• What kind of insulation is typically required for high-temperature refrigerant lines?
• What describes the start of the split system air conditioner's sequence of operation?
• The continuity through a de-energized relay coil is checked by measuring what?
• How must outdoor condensing units be installed in areas that are prone to flooding?
• What could an unusual noise from the air conditioning unit indicate?
• When setting the indoor blower speed on an air conditioner, what is the recommended CFM of airflow per ton of cooling?
• What is the role of a vapor barrier on insulated supply ducts?
• What is the significance of a pressure-temperature chart for refrigerants?
• When should an air conditioning system be serviced to ensure optimal performance?
• Where should a technician measure resistance to check the line voltage wiring of a compressor?
• What is the effect of an open internal overload protector in a hermetic compressor?
• What happens if the head pressure in a condenser becomes too low during low ambient conditions?
• What is the recommended method for testing the integrity of a low voltage circuit?
• What is the proper disposal method for a mercury bulb thermostat?
• In a given cooling scenario, what does a house feeling "drafty" with properly sized ductwork and high supply face velocities indicate?
• If the technician believes that a hermetic compressor has a permanently open internal overload protector, when should the technician test the compressor?
• Why is suction line insulation important?
• What is the function of a blower motor in an air conditioning system?
• With the thermostat blower switch set to ON, which measurement indicates a call for residential indoor blower operation?
• When installing a motorized economizer, it is important to ensure that:
• Which component is responsible for compressing the refrigerant in a cooling system?
• What factor affects the efficiency of an air conditioning unit the most?
• A delay on break relay delays the load from which of the following?
• What is a significant benefit of insulating supply ducts in unconditioned spaces?
• To achieve a specific SEER rating, which components must be matched?
• What is the maximum internal voltage that electronic air cleaners can operate with?
• To what minimum vacuum level should an air conditioner refrigerant circuit be evacuated?
• In what scenario should a technician be cautious when using carbon dioxide for leak detection?
• How can a technician check if a three-phase blower motor is rotating in the proper direction?
• When a technician finds a leak in a flexible duct system, what should be checked?
• Which type of compressor is known for its high efficiency and effectiveness in varying load conditions?
• What component is indicated when one experiences failure in an air conditioning system that requires prolonged cooling cycles?
• A system supply airflow check is used primarily to diagnose which issue?
• What happens to the cooling capacity of an air conditioning system due to return air leakage in a hot attic?
• How can you determine if your air conditioning system is overcharging with refrigerant?
• What is the purpose of a crankcase heater in an air conditioning system?
• What is one potential consequence of a dirty air filter in an air conditioning system?
• Which condition can result in reduced design capacity in an air conditioner?
• What can happen if ductwork has significant leaks?
• What is the primary function of a curb gasket in air conditioning installations?
• Supply ducts running through unconditioned spaces should be insulated and have what?
• Which of the following is a benefit of using a properly sized 4" pleated media filter compared to a 1" fiberglass air filter?
• What is considered a normal temperature split between supply and return air in an air conditioning system?
• What can excessive pressure in a refrigerant system indicate?
• Which type of maintenance is essential for prolonging the life of an air conditioning system?
• During the refrigeration cycle, where does the refrigerant absorb heat?
• What should be checked during a thorough air conditioning system inspection?
• Which method is effective in reducing vibration noise transmission in sheet metal ductwork?
• For indoor air quality purposes, the minimum horizontal distance between an economizer or fresh air intake and plumbing vent shall be:
• What is the recommended maximum external static pressure for heating and cooling equipment with blowers rated for 5 tons of cooling or less?
• What must be considered when installing an electronic air cleaner in terms of electrical safety?
• What component is responsible for compressing the refrigerant in an air conditioning system?
• With an R-410A condensing pressure of 397 psig and a liquid line temperature of 108°F, what is the subcooling temperature?
• What is the primary purpose of a thermal expansion valve in a refrigerant system?
• What does a thermostatic expansion valve control in a refrigeration system?
• Which instrument is used to measure duct static pressure?
• What can cause an air conditioning system to short cycle?
• What is the correct method for repairing a 1" hole in a section of duct board?
• What effect does high humidity have on the operation of an air conditioning system?
• What is the typical method of staging a two-stage compressor in an air conditioning system?
• How often should an air conditioning system's refrigerant be checked?
• Electronic air cleaners do not remove:
• What type of circuit typically uses a relay for control?
• Why is it important to regularly maintain HVAC systems?
• Which component is primarily responsible for regulating the refrigerant flow in an air conditioning system?
• What is the typical operating pressure range for R-410A in a residential air conditioning system?
• Will a Capacitor Start-Capacitor Run (CSCR) motor with an open run capacitor successfully start?
• What does moderate resistance on a "bellyband" crankcase heater indicate during a service check-up?
• What is the purpose of a disc-type control in a loss-of-charge shutdown scenario?
• According to generally accepted national codes, what is the smallest size pipe that can be used to carry condensate from the secondary drain pan?
• Which of the following microfarad values indicates a good start capacitor rated at 145-175 mfd?
• How is the SEER rating used to measure an air conditioning system?
• Which of the following are the first two checks typically made on an electronic control?
• Why is annual maintenance important for air conditioning systems?
• What is a common method to test the accuracy of a thermostat?
• What is the purpose of a drain line in an air conditioning system?
• What is the appropriate method for cleaning a two-row curved condenser coil?
• What is the airflow path of an outdoor pull-through coil?
• During a maintenance call, after discussing performance with the equipment owner, what should the technician set the FAN switch to?
• How does a variable speed blower benefit an air conditioning system?
• What is superheat in an air conditioning system?
• What is the primary purpose of the evaporator in an air conditioning system?
• What is the primary function of a condenser coil?
• What does a high head pressure in a refrigeration system usually indicate?
• What safety measure should be taken when handling refrigerants?
• What does the term "latent heat" refer to in cooling systems?
• What is the purpose of a system strain relief in an HVAC application?
• Which component regulates the temperature in the evaporator coil?
• Which of the following is a proper operation for a packaged air conditioning system using an electronic control board?
• What is the purpose of a reversing valve in heat pump systems?
• What is the formula to calculate the CFM based on velocity and area?
• What is the purpose of a suction line accumulator in a refrigeration system?
• What is a common sign of a refrigerant leak in an air conditioning system?
• What role do thermal expansion valves (TXV) play in refrigerant systems?
• What is the purpose of a combustion analyzer in a gas furnace?
• What effect does overcharging have on subcooling?
• What is the role of insulation in refrigerant lines?
• What is a probable cause for a high temperature differential across the evaporator of an air conditioner?
• What can low airflow through an EVAP coil result in?
• What do the initials "S.E.E.R." represent?
• What is a common symptom of low refrigerant levels in an air conditioning system?
• What is the function of a dual capacitor in an air conditioning unit?
• What does a bright red or orange glow from the resistance elements in a duct heater indicate?
• What commonly indicates a problem with the compressor in an air conditioning system?
• What is the recommended position for outdoor condenser units to ensure efficient operation?
• A compressor with proper voltage and a hard start relay and capacitor draws lock rotor amps on startup. What is the most likely problem?
• What type of refrigerant is typically used in most residential air conditioning systems?
• What is the purpose of an accumulator in a refrigeration system?
• A technician finds that a system does not operate when the thermostat calls for cooling. What is the first check the technician should perform?
• What is a common function of an outdoor ambient thermostat in a commercial split system air conditioner?
• Hard start kits are typically required on which type of systems?
• What is the function of the push-button or knob on electronic leak detectors?
• What do thermostatic expansion valves regulate to a coil?
• What is a common symptom of an overcharged refrigerant system?
• During the servicing of a residential air conditioning system, what should be checked first if there is no airflow from the vents?
• What does the abbreviation HVAC stand for?
• If an air conditioning system operates in a low ambient condition, what happens to condenser operation?
• Where should a technician check the voltage to an energized compressor?
• What role does insulation play in an air conditioning system?
• In what scenario would the closing action of a disc-type control be critical?
• What does a high-pressure switch in an air conditioning system do?
• Which of the following is a key indicator of proper airflow in an air conditioning system?
• What happens to supply airflow using a PSC blower motor when adding a ducted return?
• What is the expected outcome of routine maintenance on an air conditioning system?
• When checking refrigerant levels, what is a common sign of undercharging?
• The continuity reading on a functional fuse will be:
• What is an overflow pan used for in an air conditioning system?
• What is a common cause of elevated static pressure in the duct system?
• What should be done if the air conditioning system is not cooling effectively?
• What is the primary purpose of a refrigerant in an air conditioning system?
• What is the maximum current draw for a 120V x 24V step down transformer rated at 40 VA?
• What is usually the primary cause for a compressor to overheat?
• What type of metering device is generally considered for the subcooling method when checking charge?
• In a low voltage circuit, a corroded wire-to-terminal connection acts in the circuit like a(n):
• According to ANSI/ACCA Manual D, when balancing dampers are used, what is their preferred location in a duct system to reduce noise?
• What effect does a dirty air filter have on an air conditioning system?
• What is the role of the metering device in a refrigeration system?
• What environmental issue is associated with older refrigerants like CFCs?