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NATE AC Service Certification With 99
Questions
The slab of a packaged air conditioner at grade level should be:
A. up against the structure to provide added support. B. on a frame attached to the structure to improve service access. C. where it can be bonded to the structure to prevent sinking of the slab. D. isolated from the structure to minimize noise transmission. - โ โ *D What precautions need to be taken with packaged AC system with ductwork installed outside?
A. The duct must be sized with .2 friction rate B. Elbows must have turning vanes C. It must have seismic bracing D. It must be insulated and weatherproofed - โ โ *D What do the initials "S.E.E.R." represent?
A. Summer Energy Efficiency Rating
B. Seasonal Energy Efficiency Ratio C. Supplementary Energy Efficiency Rating D. Summer Energy Efficiency Ratio - โ โ B. Seasonal Energy Efficiency Ratio Which of the following is a benefit in using a properly sized 4" pleated media filter compared to a 1" fiberglass air filter?
A. Equipment efficiency will be cleaned and reused B. The media filter can be cleaned and reused C. Indoor air quality will be improved D. Removes odors and particles - โ โ *C What does the minimum circuit ampacity (MCA) listed on the dataplate is used to determine the:
A. size of the branch circuit conductors that supply the equipment. B. measured amp draw of the equipment. C. maximum fuse or circuit breaker size. D. electric power in watts used by the equipment. - โ โ A. size of the branch circuit conductors that supply the equipment. Which measures duct static pressure?
B. Spray the coil from the inside and the outside of the condenser with an acid base cleaner C. Brush the outside of the condenser with a bristle brush and water flush D. Separate the two rows of coils, spray all surfaces with proper coil cleaner and water flush - โ โ *D. Separate the two rows of coils, spray all surfaces with proper coil cleaner and water flush A residential supply diffuser that is noisy because of a loose vane is best serviced by:
A. reducing the air volume. B. changing the fan speed. C. replacing the noisy vane. D. replacing the diffuser. - โ โ D. replacing the diffuser. Which of the following is a likely problem if the air across the evaporator of an air conditioner has a high temperature differential?
A. Too much charge B. Clogged expansion valve C. Dirty filter or evaporator D. Dirty condenser coil - โ โ *C
When performing a cycling check during a maintenance call, the technician should first check with the owner of the equipment for their opinion of performance. The next step is to turn the unit off at the thermostat SYSTEM switch. The technician should set the FAN switch to:
A. AUTO and measure the voltage from the R to G terminal. B. ON and measure the voltage from the R to the W1 terminal. C. ON and check that the blower is running. D. AUTO and check that the blower is running. - โ โ *C To properly check the computer and its line voltage wiring the technician should measure resistance at the:
A. load side of the compressor contactor. B. compressor terminals. C. capacitor. D. crankcase heater. - โ โ *A On a residential no cooling call, typically the first check would be:
A. the air filter. B. the control voltage at the transformer.
This indicates the system:
A. is overcharged. B. has excess airflow C. is undercharged. D. has low airflow - โ โ C. is undercharged. What effect does overcharging have on subcooling?
A. It depends on which type of refrigerant is used B. It increases it C. It decreases it D. It depends on the metering device used - โ โ *D It depends on the metering device used When an air conditioner with a thermostatic expansion valve installed is overcharged, the excess charge should be removed by recovering some charge and checking:
A. system pressures. B. superheat. C. subcooling. D. head pressure. - โ โ *C. subcooling
With an R-410A condensing pressure of 397 psig and a liquid line temperature of 108degF, what is the subcooling temperature?
A. 36degF B. 24degF C. 16degF D. 8degF - โ โ D. 8degF What is the maximum acceptable supply voltage tolerance for a 120 V circuit?
A. +/-3% B. +/-5% C. +/-10% D. +10% / -15% - โ โ B. +/-5% a compressor with proper voltage and a hard start relay and capacitor draws lock rotor amps on startup. Which of the following is most likely the problem?
A. The unit is overcharged. B. The potential relay is open. C. The start and run windings are open.
C. Supply wires are oversized. D. Duct heaters are operating properly. - โ โ A. Flow of air is insufficient. During an annual service check up, it is discovered that there is a moderate amount of resistance on a "bellyband" crankcase heater. What does this condition indicate?
A. The crankcase heater will operate B. Line voltage is insufficient. C. Supply wires are oversized. D. Duct heaters are operating properly. - โ โ *A If an air conditioning system needs to operate in a low ambient condition, the condenser may become too efficient. What happens to condenser operation and what can be done to counteract this condition?
A. The head pressure becomes too low and the superheat needs to be lowered B. The head pressure becomes too low and the superheat needs to be raised C. The head pressure becomes too low and the condenser fan motor needs to be slowed or stopped
D. The suction pressure becomes too high and a low ambient controller will lower it - โ โ *B Will a Capacitor Start-Capacitor Run (CSCR) motor that has an open run capacitor start?
A. No, it would be unable to start without the run capacitor B. It may start, but it draws a higher than normal running current C. Yes, it will start, but it will run backwards D. It can only start if the voltage is higher - โ โ *A Which microfarad value indicates a good start capacitor rated at 145- 175 mfd?
A. 130 B. 160 C. 180 D. 190 - โ โ B. 160 What effect does insufficient voltage have on a solenoid valve?
A. It causes flash gas formation B. The valve will operate normally C. The valve will remain half open
D. A crankcase heater that is open - โ โ A. An undersized suction line What would cause a voltage reading accross a closed contact in a 24V control circuit?
A. Can only be read with a true RMS meter B. 24V is "sneaking" from another part of the circuit C. Pitted or dirty contacts D. Normal operation - โ โ C. Pitted or dirty contacts Which of the following are the first two checks typically made on an electronic control?
A. Presence of proper input signals and proper output voltages B. Presence of any on board transformer voltages and proper output voltages C. Ohm check of all sensors and solder side continuity checks D. Continuity of all terminals and component side checks - โ โ A. Presence of proper input signals and proper output voltages How should a technician evaluate the circuitry when the wiring diagram is missing?
A. Use a diagram from a similar equipment model
B. Completely rewire the unit C. Redraw the circuits on a sketch pad D. All equipment is wired the same - โ โ *A In a low voltage circuit, a corroded wire-to-terminal connection acts in the circuit like a(n):
A. additional inductor. B. additional capacitor. C. additional resistor. D. low ohm short. - โ โ C. additional resistor The continuity reading on a functional fuse will be:
A. 0 ohms. B. 50 - 100 ohms C. 500 - 1000 ohms D. infinite ohms. - โ โ *A Where should a technician check the voltage to an energized compressor?
A. At the main electrical panel
B. bypassed. C. hot. D. running. - โ โ A. cool. diagram #50 missing page # Using the diagram above, what is the voltage across T1 & L1 with the compressor contactor de-energized and compressor winding intact?
A. 0V B. Less than 120V C. 120V D. 230V - โ โ * diagram Refer to the diagram above and answer the question: When troubleshooting an energized electrical circuit on an electric heat section, 244 volts is measured across the element at points A and B and no amperage is measured. What is the problem with this system?
A. The element has a short in it B. The element is shorted to ground C. A fuse link is open
D. The electric element is open - โ โ * The continuity through a de-energized relay coil is checked by measuring:
A. volts. B. amps. C. ohms. D. watts. - โ โ C. ohms. When replacing a failed R-22 condensing unit with a new R-410A condensing unit:
A. existing R-22 evaporator must be replaced. B. suction line must be increased one pipe size. C. suction line insulation must be 3/4" D. existing R-22 evaporator can be reused. - โ โ A. existing R- evaporator must be replaced. Which of the following should be done to reduce vibration noise transmission in sheet metal ductwork?
A. Decrease fan speed to boost CFM B. Rigidly anchor ductwork to the structure
A. Cover the backside of the misaligned vanes with ducts tape B. None, the entire register should be replaced C. Reduce airflow to the noisy register D. Realign the misaligned van with pliers - โ โ *B The technician has determined a supply in a flexible duct system is leaking. Which of the following should be checked?
A. All connections and outer layers of duct only B. All take-off connections and outer layers of duct only C. All connections and longitudinal seams D. All connections including inner and outer layers - โ โ D. All connections including inner and outer layers How would a technician repair a 1" hole in a section of duct board?
A. Cut out the hole, and fabricate, staple and tape a plug in place to fill the hole B. Cut out the hole and fabricate and tape a plug in place to fill the hole C. Cut out the hole and seal over the location with foil tape and mastic D. Replace the entire section of duct board - โ โ *C Service site conditions are:
*House feels "drafty" in cooling, *Properly sized 3-1/2 ton split system, *High supply face velocities *Ductwork is properly sized, *Total CFM 1400 What do these readings indicate?
A. The system is operating normally and there is nothing wrong B. The returns are undersized C. The system is operating normally but the supply registers are too restrictive D. The blower is set at too high CFM - โ โ C. The system is operating normally but the supply registers are too restrictive In a simple refrigeration system, the refrigerant boils in the:
A. metering device. B. compressor. C. evaporator. D. condenser. - โ โ C. evaporator. To achieve a specific SEER rating, which components must be matched?
