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NATE Air Conditioning Troubleshooting

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. When troubleshooting a split-system air conditioner - it is found that the compressor motor is humming but not starting. Technician A says that it could be an open internal overload protector. Technician B says that it could be a blown fuse. Which te
An uninsulated suction line and a restricted metering device
The superheat increases and the subcooling decreases
Both technicians are incorrect
The oil pump pressure and the crankcase pressure

2. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
It would cause the low-side pressure to decrease
Low discharge pressure - high suction pressure - and low amp draw

3. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
The sensing bulb at a lower temperature than the valve body
Technician B
The superheat increases and the subcooling decreases

4. Which of the following will cause excessive discharge pressures on an air conditioning system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Both technicians are correct
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An increase in suction pressure and an increase in discharge pressure

5. An air conditioning system that uses a fan center has an inoperable indoor blower. When the thermostat is set for cooling and dialed below room temperature - a test with the voltmeter shows that there is 24 volts across terminals 'are' and 'G' at the
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
High superheat and low discharge pressure
A bad thermostat

6. What component is most often the cause of a start capacitor failure...
A start relay
Current in the compressor circuit
Both technicians are incorrect
Bad compressor valve

7. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
The superheat will increase and the low-side pressure will decrease
Low voltage and a faulty start relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The oil pump pressure and the crankcase pressure

8. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An increase of air leakage from ductwork
An undercharge and low ambient conditions
A low refrigerant charge
Whenever necessary

9. A technician arrives on the job and the customer complains that there is no cooling on his rooftop unit. Troubleshooting the system - the technician finds that the compressor is faulty. He notices that there is another faulty compressor laying next t
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Current in the compressor circuit
Broken rings+broken valves+seized bearings
An open internal overload protector

10. A customer calls and complains that her high-efficiency air conditioning system is operating - but is not cooling properly. Further investigation shows that the system is using a TXV type of metering device. A subcooling check shows that the system a
Run with high head and high suction pressure
An increase in suction pressure and an increase in discharge pressure
The external equalizer could be plugged
Evaporator and compressor

11. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
High suction pressure and low superheat
A start relay

12. What are the symptoms of an air conditioning system that has a low charge...
Whenever necessary
3 psig
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The low-side pressure will decrease and the evaporator coil will be partially frosted

13. Insufficient airflow can be caused by...
High superheat and low discharge pressure
Technician B
The superheat will increase and the low-side pressure will decrease
An increase of air leakage from ductwork

14. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
20 to 30
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Short cycling and insufficient dehumidification
The sensing bulb at a lower temperature than the valve body

15. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
Technician A is correct
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The superheat increases and the subcooling decreases
Technician B

16. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
An increase of air leakage from ductwork
Run with high head and high suction pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Partially frosted evaporator and high superheat

17. A customer calls and complains that his air conditioning system is not operating properly. It is noticed that the compressor is not operating. A check on the run capacitor shows that there is 33 uf and the rating on the capacitor is 40 uf. Technician
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Condenser fans operating during a low ambient condition and a low suction pressure
Low voltage and a faulty start relay

18. What are two problems that can cause an air conditioning system to have an excessively high superheat...
The sight glass is full of liquid+the sight glass is full of gas
An uninsulated suction line and a restricted metering device
The external equalizer could be plugged
Short cycling and insufficient dehumidification

19. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
110-120
Technician A is correct

20. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...

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21. A commercial customer calls on a 90
Technician B
Technician B
The external equalizer could be plugged
The system has been overcharged+The system has air trapped in the condenser

22. A commercial customer calls complaining that her rooftop air conditioning system is not operating. The technician arrives on the job and sets the thermostat to cooling - then notices that the indoor fan is not operating. The technician then sets the

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23. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
50-65
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Low discharge pressure - high suction pressure - and low amp draw
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

24. A restricted air filter in an air conditioning system can be identified by...
A low refrigerant charge
Low superheat
The sight glass is full of liquid+the sight glass is full of gas
Technician B

25. What are the operating pressures of an oil pressure safety switch...
An increase of air leakage from ductwork
The oil pump pressure and the crankcase pressure
An overcharged system
A start relay

26. Superheat is found in an air conditioning system in the...
A defective circuit breaker
Evaporator and compressor
Technician B
Whenever necessary

27. A customer calls to complain that his central air conditioning system is not cooling properly. The technician arrives on the job. He or she notices that the indoor blower has adequate airflow and the outdoor condenser fan is operating - but the compr
An undercharge and low ambient conditions
An open internal overload protector
Partially frosted evaporator and high superheat
Increases starting torque

28. The temperature range of the suction line from an air conditioning system should be...
A sensing bulb improperly connected to the suction line
An overcharged system
50-65
Short cycling and insufficient dehumidification

29. A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that the outdoor condensing unit is operating - but the indoor blower is not in operation. Technician A says that it is possible that it is a bad fu
Both technicians are incorrect
Technician B
Technician A
A sensing bulb improperly connected to the suction line

30. Air filters should be replaced...
Whenever necessary
It keeps a constant superheat in the evaporator
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

31. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
An undercharge and low ambient conditions
A blown fuse
Technician B

32. What problem can cause an increase of discharge pressure and an increase of suction pressure...
The system has been overcharged+The system has air trapped in the condenser
An overcharged system
A bad thermostat
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

33. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Technician A
Low superheat
The sight glass is full of liquid+the sight glass is full of gas
The superheat increases and the subcooling decreases

34. A customer calls and complains that her high-efficiency air conditioning system is operating - but is not cooling properly. Further investigation shows that the system is using a TXV type of metering device. A subcooling check shows that the system a
Contains a solenoid coil and one or more sets of contacts
Both technicians are correct
Technician B
The external equalizer could be plugged

35. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
Technician A
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B

36. When troubleshooting a split-system air conditioner - it is found that the compressor motor is humming but not starting. Technician A says that it could be an open internal overload protector. Technician B says that it could be a blown fuse. Which te
Both technicians are incorrect
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The oil pump pressure and the crankcase pressure
An overcharged system

37. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser

38. The technician observes that the compressor is not operating. The compressor windings read 5 ohms start to run - run to common is opened - and start to common is opened. The technician concludes that...
A defective circuit breaker
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The internal overload is opened
A sensing bulb improperly connected to the suction line

39. Which of the following could be the cause for a system's discharge and suction pressure being low...
The sight glass is full of liquid+the sight glass is full of gas
Technician B
A low refrigerant charge
A restricted metering device

40. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Both technicians are incorrect
3 psig
Always have some liquid present in the bulb and diaphragm
('Y' and 'C') and ('G' and 'C')

41. A system that is operating with a clear sight glass shows...
An increase in low-side pressure
The sight glass is full of liquid+the sight glass is full of gas
Technician B
'G' to 'C'

42. What causes the automatic expansion valve to close...
50-65
An increase in suction pressure and an increase in discharge pressure
The oil pump pressure and the crankcase pressure
An increase in low-side pressure

43. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
Technician B
A restricted metering device
Technician B

44. A hard-start kit consists of...
Technician A is correct
An undercharge and low ambient conditions
Low discharge pressure - high suction pressure - and low amp draw
A start capacitor and a solid-state relay

45. The best description of a relay would be...
Lack of airflow
Technician B
A sensing bulb improperly connected to the suction line
Contains a solenoid coil and one or more sets of contacts

46. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The internal overload is opened
Current in the compressor circuit
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

47. What are two common symptoms of a rooftop air conditioning system that operates with a reverse-acting high-pressure control stuck in the closed position...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Low discharge pressure - high suction pressure - and low amp draw
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B

48. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
A blown fuse
An undercharge and low ambient conditions
Technician B
A start capacitor and a solid-state relay

49. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The superheat will increase and the low-side pressure will decrease
The discharge pressure increases and the amperage increases
An increase in low-side pressure
('Y' and 'C') and ('G' and 'C')

50. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
Run with high head and high suction pressure