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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. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
Both technicians are incorrect
Both technicians are correct
20 to 30

2. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Both technicians are incorrect
An uninsulated TXV sensing bulb
The discharge pressure increases and the amperage increases

3. Technician A says ' When charging a system using the superheat method - adding refrigerant to the system will increase the superheat.' Technician B says 'When charging a system using the superheat method - adding refrigerant will decrease the superhe
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B
Always have some liquid present in the bulb and diaphragm

4. If 24 volts are present to the contactor coil on an air conditioning system and the condenser fan or compressor is inoperative - which of the following could be at fault...
Both technicians are incorrect
Whenever necessary
High suction pressure and low superheat
A blown fuse

5. 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
The discharge pressure increases and the amperage increases
A restricted metering device
An open internal overload protector
Condenser fans operating during a low ambient condition and a low suction pressure

6. Which of the following can cause low superheat in a TXV system...
The oil pump pressure and the crankcase pressure
Technician B
A start relay
An uninsulated TXV sensing bulb

7. Which of the following is a possible cause for a compressor to overheat...
An uninsulated suction line and a restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A low refrigerant charge
An undercharged system+insufficient airflow over the evaporator coil

8. Why is it unsafe to operate an air conditioning system with a low charge...
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Always have some liquid present in the bulb and diaphragm
A missing air filter+improper rotation of the indoor blower+blower too small

9. A liquid-charged TXV bulb will...
Whenever necessary
Technician A
Always have some liquid present in the bulb and diaphragm
Technician B

10. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The system has been overcharged+The system has air trapped in the condenser
Technician A is correct
A vacuum test+oil traces around fittings+soap bubble solution
Low discharge pressure - high suction pressure - and low amp draw

11. What component is most often the cause of a start capacitor failure...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A bad thermostat
A start relay
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

12. Superheat is found in an air conditioning system in the...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A restricted metering device
A sensing bulb improperly connected to the suction line
Evaporator and compressor

13. Insufficient airflow can be caused by...
Current in the compressor circuit
An increase of air leakage from ductwork
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A start relay

14. What is the purpose of a CPR valve...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A blown fuse
It is used to control refrigerant pressure in the compressor crankcase
An uninsulated TXV sensing bulb

15. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A blown fuse
The low-side pressure will decrease and the evaporator coil will be partially frosted
An increase in suction pressure and an increase in discharge pressure
Both technicians are correct

16. What is the purpose of an EPR valve...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The superheat will increase and the low-side pressure will decrease
A start relay

17. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An undercharge and low ambient conditions
Lack of airflow
An overcharged system
A sensing bulb improperly connected to the suction line

18. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Both technicians are incorrect
An overcharged system
Lack of airflow
Broken rings+broken valves+seized bearings

19. 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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20. 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...
An open internal overload protector
Both technicians are incorrect
The internal overload is opened
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

21. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
The superheat will increase and the low-side pressure will decrease
Contains a solenoid coil and one or more sets of contacts
Technician B

22. What problem or problems can cause low discharge and suction pressure...
Condenser fans operating during a low ambient condition and a low suction pressure
Current in the compressor circuit
High suction pressure and low superheat
An undercharged system+insufficient airflow over the evaporator coil

23. 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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24. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
A start capacitor and a solid-state relay
Low discharge pressure - high suction pressure - and low amp draw
A missing air filter+improper rotation of the indoor blower+blower too small
The low-side pressure will decrease and the evaporator coil will be partially frosted

25. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A sensing bulb improperly connected to the suction line
Technician B
Lack of airflow
An increase in suction pressure and an increase in discharge pressure

26. 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
Technician A is correct
Both technicians are incorrect
High superheat and low discharge pressure
The external equalizer could be plugged

27. A technician receives an air conditioning service call stating that the system is operating but isn't cooling properly. When the technician arrives - she notices that the compressor has recently been changed and it is an are-22 system. She checks the
Broken rings+broken valves+seized bearings
Flooding the condenser - cycling condenser fans - and dampering condenser air
A start capacitor and a solid-state relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

28. What causes the automatic expansion valve to close...
An increase in low-side pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A vacuum test+oil traces around fittings+soap bubble solution
Clean the condenser coil

29. What causes the automatic expansion valve to close...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Current in the compressor circuit
An increase in low-side pressure
A sensing bulb improperly connected to the suction line

30. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Condenser fans operating during a low ambient condition and a low suction pressure
High suction pressure and low superheat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A restricted metering device

31. A hard-start kit for an air conditioning system...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Condenser fans operating during a low ambient condition and a low suction pressure
Increases starting torque
Technician A is correct

32. Technician A says that to manually pump down an air conditioning system with a two-position service valve - the liquid line must be front-seated and the high- and low-side pressure will decrease to 0 psig when the pump-down is complete. Technician B
Condenser fans operating during a low ambient condition and a low suction pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
An increase in suction pressure and an increase in discharge pressure
Technician A is correct

33. A hard-start kit consists of...
An overcharged system
Technician B
A start capacitor and a solid-state relay
The oil pump pressure and the crankcase pressure

34. If a rooftop air conditioning system does not have any means of low ambient protection - what will be two symptoms of the system when operating under a low ambient condition...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
High suction pressure and low superheat
High superheat and low discharge pressure
Low voltage and a faulty start relay

35. 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
An increase in suction pressure and an increase in discharge pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
High superheat and low discharge pressure
Broken rings+broken valves+seized bearings

36. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Run with high head and high suction pressure
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
110-120

37. 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 open internal overload protector
'G' to 'C'
The internal overload is opened
'G' to 'C'

38. A compressor having tight bearings would cause the current value to...
An open internal overload protector
An increase in low-side pressure
The superheat will increase and the low-side pressure will decrease
Rise more than normal

39. A customer calls with an insufficient cooling complaint on a 90
Bad compressor valve
It is used to control refrigerant pressure in the compressor crankcase
Contains a solenoid coil and one or more sets of contacts
Technician B

40. A customer who owns a split air conditioning system complains that his system has been running but his house doesn't seem to be cooling properly. When the service technician arrives on the job - he or she finds that the indoor blower is operating and
Technician B
An undercharged system+insufficient airflow over the evaporator coil
Clean the condenser coil
Low discharge pressure - high suction pressure - and low amp draw

41. A hard-start kit for an air conditioning system...
Technician B
Technician B
An undercharge and low ambient conditions
Increases starting torque

42. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An uninsulated suction line and a restricted metering device
It is used to control refrigerant pressure in the compressor crankcase
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

43. 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...
An undercharged system+insufficient airflow over the evaporator coil
Condenser fans operating during a low ambient condition and a low suction pressure
The sight glass is full of liquid+the sight glass is full of gas
A bad thermostat

44. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The internal overload is opened
Both technicians are incorrect

45. 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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46. The temperature range of the suction line from an air conditioning system should be...
Lack of airflow
An undercharge and low ambient conditions
An uninsulated suction line and a restricted metering device
50-65

47. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
The oil pump pressure and the crankcase pressure
The internal overload is opened
Rise more than normal

48. A split-system air conditioner that uses a piston-type metering device is to be charged with are-22. Technician A says that the outdoor dry-bulb temperature is needed to determine the proper superheat. Technician B says that the indoor wet-bulb tempe
Both technicians are correct
The internal overload is opened
('Y' and 'C') and ('G' and 'C')
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

49. A system that uses a thermal electric expansion valve...
20 to 30
Low voltage and a faulty start relay
Low superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

50. A customer calls and says that her air conditioning system is not cooling properly. Upon arrival - a technician notices that the suction line and compressor have frost buildup. Technician A says that the problem is probably a low charge. Technician B
An increase in low-side pressure
Lack of airflow
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B