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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. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Technician B
Run with high head and high suction pressure
Technician B
Both technicians are incorrect

2. What causes the automatic expansion valve to close...
Partially frosted evaporator and high superheat
Flooding the condenser - cycling condenser fans - and dampering condenser air
3 psig
An increase in low-side pressure

3. A compressor motor starts and operates for a short period of time and cycles on the external overload protector. What are two possible problems that could cause this...
Low superheat
Low voltage and a faulty start relay
It would cause the low-side pressure to decrease
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

4. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
50-65
An uninsulated TXV sensing bulb
An open internal overload protector
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

5. What are the operating pressures of an oil pressure safety switch...
Rise more than normal
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The oil pump pressure and the crankcase pressure
Technician A is correct

6. A compressor having tight bearings would cause the current value to...
Technician A is correct
Rise more than normal
A defective circuit breaker
Always have some liquid present in the bulb and diaphragm

7. Air filters should be replaced...
Whenever necessary
Run with high head and high suction pressure
Broken rings+broken valves+seized bearings
Technician B

8. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Contains a solenoid coil and one or more sets of contacts
High suction pressure and low superheat
Technician B
An overcharged system

9. Which of the following can cause excessive subcooling...
A start relay
A low refrigerant charge
An overcharged system
Low superheat

10. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
An increase in low-side pressure
A defective circuit breaker
The superheat increases and the subcooling decreases

11. 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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12. What are the symptoms of a TXV air conditioning system if it has lost its charge...
A start capacitor and a solid-state relay
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The external equalizer could be plugged
The superheat will increase and the low-side pressure will decrease

13. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
Technician B
It is used to control refrigerant pressure in the compressor crankcase
Technician B

14. Insufficient airflow can be caused by...
Both technicians are incorrect
An increase of air leakage from ductwork
The oil pump pressure and the crankcase pressure
'G' to 'C'

15. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
Bad compressor valve
Technician A
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

16. When using a vapor-charged TXV bulb - it is necessary to have...
Both technicians are incorrect
An open internal overload protector
The system has been overcharged+The system has air trapped in the condenser
The sensing bulb at a lower temperature than the valve body

17. A compressor motor starts and operates for a short period of time and cycles on the external overload protector. What are two possible problems that could cause this...
An overcharged system
Technician B
Broken rings+broken valves+seized bearings
Low voltage and a faulty start relay

18. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
An increase in suction pressure and an increase in discharge pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser
50-65
Technician B

19. The temperature range of the suction line from an air conditioning system should be...
Technician B
The sight glass is full of liquid+the sight glass is full of gas
50-65
An undercharge and low ambient conditions

20. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An overcharged system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The superheat will increase and the low-side pressure will decrease
The superheat increases and the subcooling decreases

21. What component is most often the cause of a start capacitor failure...
An undercharge and low ambient conditions
A start relay
The sensing bulb at a lower temperature than the valve body
Technician B

22. A customer calls with an insufficient cooling complaint on a 90
Technician B
Bad compressor valve
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
'G' to 'C'

23. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated suction line and a restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The superheat increases and the subcooling decreases

24. Which of the following is a common cause of an excessively low superheat on a TXV system...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A sensing bulb improperly connected to the suction line
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Both technicians are incorrect

25. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
Broken rings+broken valves+seized bearings
20 to 30
110-120

26. 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
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
Technician A is correct
Partially frosted evaporator and high superheat

27. What is the common cause of a compressor burnout...
Rise more than normal
It is used to control refrigerant pressure in the compressor crankcase
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B

28. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Low superheat
('Y' and 'C') and ('G' and 'C')

29. A system that uses a thermal electric expansion valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
20 to 30
The superheat will increase and the low-side pressure will decrease
A start relay

30. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are incorrect
Partially frosted evaporator and high superheat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

31. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
'G' to 'C'
A start relay
Broken rings+broken valves+seized bearings
A plugged filter drier

32. A system that uses a thermal electric expansion valve...
Technician B
High superheat and low discharge pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The low-side pressure will decrease and the evaporator coil will be partially frosted

33. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
An increase in low-side pressure
Short cycling and insufficient dehumidification
Technician B

34. A restricted air filter in an air conditioning system can be identified by...
Evaporator and compressor
Whenever necessary
The external equalizer could be plugged
Low superheat

35. A system that is operating with a clear sight glass shows...
A blown fuse
The sight glass is full of liquid+the sight glass is full of gas
Evaporator and compressor
Run with high head and high suction pressure

36. 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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37. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
A bad thermostat
Broken rings+broken valves+seized bearings

38. A liquid-charged TXV bulb will...
It would cause the low-side pressure to decrease
High suction pressure and low superheat
Always have some liquid present in the bulb and diaphragm
Low discharge pressure - high suction pressure - and low amp draw

39. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Increases starting torque
Evaporator and compressor
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A sensing bulb improperly connected to the suction line

40. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It would cause the low-side pressure to decrease
Increases starting torque
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Low superheat

41. Which of the following can cause excessive subcooling...
A blown fuse
The system has been overcharged+The system has air trapped in the condenser
An overcharged system
A restricted metering device

42. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Increases starting torque
Run with high head and high suction pressure
Low voltage and a faulty start relay

43. Which of the following will cause excessive discharge pressures on an air conditioning system...
Lack of airflow
The sight glass is full of liquid+the sight glass is full of gas
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B

44. Superheat is found in an air conditioning system in the...
20 to 30
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Evaporator and compressor

45. 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
Both technicians are incorrect
A restricted metering device
Technician B
'G' to 'C'

46. 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
A sensing bulb improperly connected to the suction line
Both technicians are correct
An overcharged system
A plugged filter drier

47. A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that the system is using are-22 with the high-side pressure at 290 psig and the low-side pressure at 85 psig. The ambient temperature is 85
The superheat will increase and the low-side pressure will decrease
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician A
The sight glass is full of liquid+the sight glass is full of gas

48. Why is it unsafe to operate an air conditioning system with a low charge...
Technician B
A bad thermostat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A blown fuse

49. Why is it unsafe to operate an air conditioning system with a low charge...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An overcharged system
An acid-core suction line drier
An increase of air leakage from ductwork

50. 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 discharge pressure increases and the amperage increases
It is used to control refrigerant pressure in the compressor crankcase
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure