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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 component is most often the cause of a start capacitor failure...
The system has been overcharged+The system has air trapped in the condenser
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A start relay
High superheat and low discharge pressure

2. A liquid-charged TXV bulb will...
A defective circuit breaker
An increase in low-side pressure
Always have some liquid present in the bulb and diaphragm
An increase in suction pressure and an increase in discharge pressure

3. 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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4. 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...
110-120
Low discharge pressure - high suction pressure - and low amp draw
An increase of air leakage from ductwork
The internal overload is opened

5. 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
Bad compressor valve
'G' to 'C'
The sight glass is full of liquid+the sight glass is full of gas
Technician A

6. 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 overcharged system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

7. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
'G' to 'C'
Low superheat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Partially frosted evaporator and high superheat

8. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
'G' to 'C'
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The discharge pressure increases and the amperage increases

9. What are common methods that are used for leak-testing a system...
Always have some liquid present in the bulb and diaphragm
A vacuum test+oil traces around fittings+soap bubble solution
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It would cause the low-side pressure to decrease

10. A system that is operating with a clear sight glass shows...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The sight glass is full of liquid+the sight glass is full of gas
An increase in suction pressure and an increase in discharge pressure

11. What problem or problems can cause low discharge and suction pressure...
An overcharged system
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
An undercharged system+insufficient airflow over the evaporator coil

12. 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
It keeps a constant superheat in the evaporator
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A blown fuse
The sensing bulb at a lower temperature than the valve body

13. 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...
A start capacitor and a solid-state relay
High superheat and low discharge pressure
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

14. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
Technician B
The external equalizer could be plugged
An acid-core suction line drier

15. The best description of a relay would be...
An uninsulated TXV sensing bulb
Low voltage and a faulty start relay
A restricted metering device
Contains a solenoid coil and one or more sets of contacts

16. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
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

17. Insufficient airflow can be caused by...
Short cycling and insufficient dehumidification
An increase of air leakage from ductwork
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

18. 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...
Current in the compressor circuit
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
Low voltage and a faulty start relay

19. 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
High superheat and low discharge pressure
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
Current in the compressor circuit

20. What are two common symptoms of refrigerant leaks in an air conditioning system...
A low refrigerant charge
High suction pressure and low superheat
Partially frosted evaporator and high superheat
Bad compressor valve

21. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
An open internal overload protector
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Lack of airflow
An acid-core suction line drier

22. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
('Y' and 'C') and ('G' and 'C')
It keeps a constant superheat in the evaporator
Technician B

23. What are the operating pressures of an oil pressure safety switch...
3 psig
Flooding the condenser - cycling condenser fans - and dampering condenser air
It would cause the low-side pressure to decrease
The oil pump pressure and the crankcase pressure

24. 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
Broken rings+broken valves+seized bearings
Both technicians are correct
The system has been overcharged+The system has air trapped in the condenser

25. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
A missing air filter+improper rotation of the indoor blower+blower too small
Technician A is correct
A vacuum test+oil traces around fittings+soap bubble solution

26. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
An open internal overload protector
An increase in suction pressure and an increase in discharge pressure
An increase in suction pressure and an increase in discharge pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

27. A liquid-charged TXV bulb will...
The discharge pressure increases and the amperage increases
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Always have some liquid present in the bulb and diaphragm
Technician B

28. A compressor having tight bearings would cause the current value to...
Current in the compressor circuit
Rise more than normal
A defective circuit breaker
A dirty condenser - recirculation of condenser air - and a defective condenser fan

29. 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
The external equalizer could be plugged
A sensing bulb improperly connected to the suction line

30. What type of problems can be caused by an oversized air conditioning system...
An open internal overload protector
The low-side pressure will decrease and the evaporator coil will be partially frosted
Short cycling and insufficient dehumidification
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

31. Which of the following can cause excessive subcooling...
An undercharged system+insufficient airflow over the evaporator coil
An overcharged system
An increase in low-side pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

32. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An acid-core suction line drier
A missing air filter+improper rotation of the indoor blower+blower too small
Short cycling and insufficient dehumidification
It would cause the low-side pressure to decrease

33. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
Technician A is correct
Contains a solenoid coil and one or more sets of contacts
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

34. 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
A sensing bulb improperly connected to the suction line
Technician B
It is used to control refrigerant pressure in the compressor crankcase
Condenser fans operating during a low ambient condition and a low suction pressure

35. 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
Evaporator and compressor
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air

36. Superheat is found in an air conditioning system in the...
Evaporator and compressor
The discharge pressure increases and the amperage increases
Run with high head and high suction pressure
Whenever necessary

37. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The system has been overcharged+The system has air trapped in the condenser
An increase of air leakage from ductwork
Flooding the condenser - cycling condenser fans - and dampering condenser air

38. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The sight glass is full of liquid+the sight glass is full of gas
The external equalizer could be plugged

39. 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 increase of air leakage from ductwork
An undercharge and low ambient conditions
'G' to 'C'
An acid-core suction line drier

40. 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
The system has been overcharged+The system has air trapped in the condenser
Both technicians are incorrect
An increase in suction pressure and an increase in discharge pressure
Both technicians are correct

41. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
'G' to 'C'
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
Lack of airflow

42. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A blown fuse
It would cause the low-side pressure to decrease
An increase in suction pressure and an increase in discharge pressure
20 to 30

43. 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
3 psig
High superheat and low discharge pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

44. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Short cycling and insufficient dehumidification
Condenser fans operating during a low ambient condition and a low suction pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
'G' to 'C'

45. 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
A blown fuse
Low superheat
The superheat will increase and the low-side pressure will decrease

46. A hard-start kit consists of...
A start capacitor and a solid-state relay
It keeps a constant superheat in the evaporator
Lack of airflow
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

47. A hard-start kit for an air conditioning system...
Increases starting torque
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Short cycling and insufficient dehumidification
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

48. 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
Rise more than normal
A start relay
('Y' and 'C') and ('G' and 'C')
The external equalizer could be plugged

49. What are two common symptoms of refrigerant leaks in an air conditioning system...
Lack of airflow
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Partially frosted evaporator and high superheat
Short cycling and insufficient dehumidification

50. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Always have some liquid present in the bulb and diaphragm
A missing air filter+improper rotation of the indoor blower+blower too small
Current in the compressor circuit
An acid-core suction line drier