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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 an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
Rise more than normal
Current in the compressor circuit
110-120

2. What is the purpose of the TXV...
Run with high head and high suction pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It keeps a constant superheat in the evaporator
20 to 30

3. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A start relay
A sensing bulb improperly connected to the suction line
An acid-core suction line drier

4. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
An open internal overload protector
An undercharged system+insufficient airflow over the evaporator coil
3 psig

5. 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
The sensing bulb at a lower temperature than the valve body
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Bad compressor valve
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

6. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Low superheat
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
An overcharged system

7. A system that is being serviced has been evacuated down to 500 microns. When the gauges are closed and the vacuum pump is turned off - the pressure starts to increase and stops at 1000 microns. Technician A says that the system has a leak and needs t
The discharge pressure increases and the amperage increases
('Y' and 'C') and ('G' and 'C')
An increase in suction pressure and an increase in discharge pressure
Technician B

8. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
High superheat and low discharge pressure
Whenever necessary
The system has been overcharged+The system has air trapped in the condenser
The superheat increases and the subcooling decreases

9. 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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10. A restricted air filter in an air conditioning system can be identified by...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Low superheat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An acid-core suction line drier

11. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
3 psig
The sight glass is full of liquid+the sight glass is full of gas
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

12. What is the common cause of a compressor burnout...
Low discharge pressure - high suction pressure - and low amp draw
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Lack of airflow

13. Which of the following can cause low superheat in a TXV system...
'G' to 'C'
Technician B
An overcharged system
An uninsulated TXV sensing bulb

14. 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
The system has been overcharged+The system has air trapped in the condenser
The superheat increases and the subcooling decreases
The oil pump pressure and the crankcase pressure

15. 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
A restricted metering device
Technician B
Run with high head and high suction pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

16. What are the symptoms of an air conditioning system that has a low charge...
The superheat increases and the subcooling decreases
Technician B
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted

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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Both technicians are incorrect
The sensing bulb at a lower temperature than the valve body

18. 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
110-120
Technician A is correct
An open internal overload protector
The low-side pressure will decrease and the evaporator coil will be partially frosted

19. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
High superheat and low discharge pressure
A missing air filter+improper rotation of the indoor blower+blower too small
The oil pump pressure and the crankcase pressure
High suction pressure and low superheat

20. Which of the following could be the cause for a system's discharge and suction pressure being low...
Clean the condenser coil
A restricted metering device
Low superheat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

21. 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
Lack of airflow
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An increase in suction pressure and an increase in discharge pressure
An open internal overload protector

22. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Increases starting torque
High superheat and low discharge pressure
An increase in suction pressure and an increase in discharge pressure
High suction pressure and low superheat

23. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
An acid-core suction line drier
Whenever necessary
Low discharge pressure - high suction pressure - and low amp draw
Technician A

24. Why is it unsafe to operate an air conditioning system with a low charge...
A defective circuit breaker
Always have some liquid present in the bulb and diaphragm
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Lack of airflow

25. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Short cycling and insufficient dehumidification
110-120
An undercharged system+insufficient airflow over the evaporator coil
High superheat and low discharge pressure

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
It keeps a constant superheat in the evaporator
Technician B
Evaporator and compressor
Technician A is correct

27. A system that is operating with a clear sight glass shows...
Technician B
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
The sight glass is full of liquid+the sight glass is full of gas

28. Which of the following can cause excessive subcooling...
Current in the compressor circuit
Technician A is correct
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An overcharged system

29. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
It keeps a constant superheat in the evaporator
Bad compressor valve
A restricted metering device
A plugged filter drier

30. 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...
A blown fuse
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
3 psig

31. What is the purpose of an EPR valve...
The internal overload is opened
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system has been overcharged+The system has air trapped in the condenser
Technician B

32. What type of problems can be caused by an oversized air conditioning system...
3 psig
Technician B
Technician B
Short cycling and insufficient dehumidification

33. 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
The sight glass is full of liquid+the sight glass is full of gas
A bad thermostat
Low discharge pressure - high suction pressure - and low amp draw
A defective circuit breaker

34. What is the purpose of an EPR valve...
Low discharge pressure - high suction pressure - and low amp draw
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An increase in suction pressure and an increase in discharge pressure
A start relay

35. 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
3 psig
A vacuum test+oil traces around fittings+soap bubble solution
A start capacitor and a solid-state relay
Technician A

36. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
3 psig
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

37. 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
Clean the condenser coil
Both technicians are correct
An open internal overload protector
Low superheat

38. 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
Technician B
The discharge pressure increases and the amperage increases
Contains a solenoid coil and one or more sets of contacts
A start capacitor and a solid-state relay

39. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
An uninsulated suction line and a restricted metering device
An acid-core suction line drier
It is used to control refrigerant pressure in the compressor crankcase

40. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
An undercharged system+insufficient airflow over the evaporator coil
3 psig
Whenever necessary

41. What are three methods for controlling a system's high-side pressure during low ambient conditions...
An open internal overload protector
A start capacitor and a solid-state relay
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B

42. Which of the following will cause excessive discharge pressures on an air conditioning system...
Bad compressor valve
A plugged filter drier
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Contains a solenoid coil and one or more sets of contacts

43. A hard-start kit for an air conditioning system...
Technician B
High suction pressure and low superheat
Partially frosted evaporator and high superheat
Increases starting torque

44. 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
The external equalizer could be plugged
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Current in the compressor circuit
High superheat and low discharge pressure

45. What component is most often the cause of a start capacitor failure...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
High suction pressure and low superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A start relay

46. Why is it unsafe to operate an air conditioning system with a low charge...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Evaporator and compressor
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The discharge pressure increases and the amperage increases

47. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

48. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A plugged filter drier
A start capacitor and a solid-state relay

49. What are two common symptoms of refrigerant leaks in an air conditioning system...
Low voltage and a faulty start relay
3 psig
Partially frosted evaporator and high superheat
Lack of airflow

50. When using a vapor-charged TXV bulb - it is necessary to have...
20 to 30
The sensing bulb at a lower temperature than the valve body
A vacuum test+oil traces around fittings+soap bubble solution
An uninsulated TXV sensing bulb