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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. What are the symptoms of a TXV air conditioning system if it has lost its charge...
3 psig
20 to 30
Evaporator and compressor
The superheat will increase and the low-side pressure will decrease

2. A restricted air filter in an air conditioning system can be identified by...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Low superheat
Technician B
The internal overload is opened

3. What are two problems that can cause an air conditioning system to have an excessively high superheat...
20 to 30
Broken rings+broken valves+seized bearings
Both technicians are incorrect
An uninsulated suction line and a restricted metering device

4. What is the common cause of a compressor burnout...
The discharge pressure increases and the amperage increases
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

5. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
It keeps a constant superheat in the evaporator
A missing air filter+improper rotation of the indoor blower+blower too small
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The superheat increases and the subcooling decreases

6. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
An open internal overload protector
High superheat and low discharge pressure
Low discharge pressure - high suction pressure - and low amp draw
An uninsulated suction line and a restricted metering device

7. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Low discharge pressure - high suction pressure - and low amp draw
Technician B
The superheat increases and the subcooling decreases

8. A hard-start kit for an air conditioning system...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Both technicians are correct
Increases starting torque
It is used to control refrigerant pressure in the compressor crankcase

9. 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 system has been overcharged+The system has air trapped in the condenser
The external equalizer could be plugged
Technician B
20 to 30

10. 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
Lack of airflow
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician A
Contains a solenoid coil and one or more sets of contacts

11. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
The internal overload is opened
A plugged filter drier
Rise more than normal
Broken rings+broken valves+seized bearings

12. A hard-start kit consists of...
A start relay
An uninsulated TXV sensing bulb
A start capacitor and a solid-state relay
Short cycling and insufficient dehumidification

13. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are correct
Technician B

14. 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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15. When using a vapor-charged TXV bulb - it is necessary to have...
An increase in low-side pressure
Run with high head and high suction pressure
The sensing bulb at a lower temperature than the valve body
High superheat and low discharge pressure

16. 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 uninsulated TXV sensing bulb
Condenser fans operating during a low ambient condition and a low suction pressure
Broken rings+broken valves+seized bearings
'G' to 'C'

17. 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
Contains a solenoid coil and one or more sets of contacts
Technician A
The oil pump pressure and the crankcase pressure
Technician B

18. A hard-start kit consists of...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An increase in low-side pressure
3 psig
A start capacitor and a solid-state relay

19. What are the operating pressures of an oil pressure safety switch...
An increase in suction pressure and an increase in discharge pressure
The oil pump pressure and the crankcase pressure
A start relay
It keeps a constant superheat in the evaporator

20. 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 start relay
High superheat and low discharge pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Condenser fans operating during a low ambient condition and a low suction pressure

21. 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 oil pump pressure and the crankcase pressure
An acid-core suction line drier
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B

22. A customer calls with an insufficient cooling complaint on a 90
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It is used to control refrigerant pressure in the compressor crankcase
Both technicians are incorrect

23. What causes the automatic expansion valve to close...
110-120
The sight glass is full of liquid+the sight glass is full of gas
Lack of airflow
An increase in low-side pressure

24. Which of the following is a possible cause for a compressor to overheat...
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A low refrigerant charge
Bad compressor valve

25. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A plugged filter drier
110-120
Technician B
The sensing bulb at a lower temperature than the valve body

26. What are the symptoms of an air conditioning system that has a low charge...
It would cause the low-side pressure to decrease
A bad thermostat
The low-side pressure will decrease and the evaporator coil will be partially frosted
An uninsulated TXV sensing bulb

27. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Technician B
It would cause the low-side pressure to decrease
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Run with high head and high suction pressure

28. When using a vapor-charged TXV bulb - it is necessary to have...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The sensing bulb at a lower temperature than the valve body
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Lack of airflow

29. What component is most often the cause of a start capacitor failure...
An uninsulated suction line and a restricted metering device
Both technicians are incorrect
A start relay
Bad compressor valve

30. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
An increase of air leakage from ductwork
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician A is correct

31. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
3 psig
20 to 30
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An increase of air leakage from ductwork

32. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Condenser fans operating during a low ambient condition and a low suction pressure
Whenever necessary
Both technicians are correct
An uninsulated suction line and a restricted metering device

33. 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 B
'G' to 'C'
It is used to control refrigerant pressure in the compressor crankcase
An undercharged system+insufficient airflow over the evaporator coil

34. 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
Clean the condenser coil
Technician A is correct
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The superheat will increase and the low-side pressure will decrease

35. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An increase in suction pressure and an increase in discharge pressure
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan

36. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Technician A
The superheat will increase and the low-side pressure will decrease
A blown fuse
It would cause the low-side pressure to decrease

37. 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
The discharge pressure increases and the amperage increases
It keeps a constant superheat in the evaporator
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

38. The best description of a relay would be...
It keeps a constant superheat in the evaporator
Contains a solenoid coil and one or more sets of contacts
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An uninsulated suction line and a restricted metering device

39. What is the purpose of an EPR valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
'G' to 'C'
Technician B
3 psig

40. 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 blown fuse
Technician B
Short cycling and insufficient dehumidification
An overcharged system

41. 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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42. Which of the following can cause low superheat in a TXV system...
An undercharge and low ambient conditions
An uninsulated TXV sensing bulb
Both technicians are correct
A start capacitor and a solid-state relay

43. 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
Run with high head and high suction pressure
The external equalizer could be plugged
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

44. A liquid-charged TXV bulb will...
Current in the compressor circuit
Always have some liquid present in the bulb and diaphragm
It would cause the low-side pressure to decrease
Clean the condenser coil

45. 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 voltage and a faulty start relay
Evaporator and compressor
An overcharged system
'G' to 'C'

46. What type of problems can be caused by an oversized air conditioning system...
Low superheat
Technician B
Short cycling and insufficient dehumidification
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

47. Air filters should be replaced...
The internal overload is opened
Whenever necessary
An overcharged system
Evaporator and compressor

48. 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
Both technicians are incorrect
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An overcharged system
A bad thermostat

49. A restricted air filter in an air conditioning system can be identified by...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Bad compressor valve
Low superheat

50. What is the purpose of an EPR valve...
A restricted metering device
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A blown fuse
Low superheat