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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. Which of the following can cause excessive subcooling...
The system has been overcharged+The system has air trapped in the condenser
Evaporator and compressor
Whenever necessary
An overcharged system

2. A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that the outdoor condensing unit is operating - but the indoor blower is not in operation. Technician A says that it is possible that it is a bad fu
A missing air filter+improper rotation of the indoor blower+blower too small
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Both technicians are incorrect
An undercharged system+insufficient airflow over the evaporator coil

3. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Current in the compressor circuit
An undercharge and low ambient conditions
An increase in suction pressure and an increase in discharge pressure
Always have some liquid present in the bulb and diaphragm

4. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
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
Contains a solenoid coil and one or more sets of contacts
An overcharged system

5. A hard-start kit consists of...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A start capacitor and a solid-state relay
A defective circuit breaker
The sensing bulb at a lower temperature than the valve body

6. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
An acid-core suction line drier
A bad thermostat
Low voltage and a faulty start relay

7. What causes the automatic expansion valve to close...
3 psig
An increase in low-side pressure
A blown fuse
A start capacitor and a solid-state relay

8. What component is most often the cause of a start capacitor failure...
A start relay
Current in the compressor circuit
A sensing bulb improperly connected to the suction line
The oil pump pressure and the crankcase pressure

9. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An open internal overload protector
A start relay
Lack of airflow
An increase in suction pressure and an increase in discharge pressure

10. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The superheat increases and the subcooling decreases
The superheat increases and the subcooling decreases
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

11. The internal overload of an air conditioning compressor senses winding temperature and...
A low refrigerant charge
Technician B
Current in the compressor circuit
The discharge pressure increases and the amperage increases

12. A compressor having tight bearings would cause the current value to...
Lack of airflow
A low refrigerant charge
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Rise more than normal

13. Which of the following will cause excessive discharge pressures on an air conditioning system...
3 psig
The external equalizer could be plugged
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

14. A compressor having tight bearings would cause the current value to...
A plugged filter drier
'G' to 'C'
Evaporator and compressor
Rise more than normal

15. What causes the automatic expansion valve to close...
3 psig
The oil pump pressure and the crankcase pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An increase in low-side pressure

16. 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
The superheat will increase and the low-side pressure will decrease
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It keeps a constant superheat in the evaporator
Technician B

17. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
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
110-120

18. 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...
Low discharge pressure - high suction pressure - and low amp draw
The internal overload is opened
Increases starting torque
Technician B

19. 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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20. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
An increase in suction pressure and an increase in discharge pressure
Evaporator and compressor
Technician B

21. 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
A start capacitor and a solid-state relay
The sight glass is full of liquid+the sight glass is full of gas
An overcharged system
Technician A

22. Air filters should be replaced...
Whenever necessary
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A start capacitor and a solid-state relay
It keeps a constant superheat in the evaporator

23. Which of the following is a possible cause for a compressor to overheat...
('Y' and 'C') and ('G' and 'C')
A low refrigerant charge
Evaporator and compressor
The discharge pressure increases and the amperage increases

24. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An acid-core suction line drier
Technician A

25. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Low discharge pressure - high suction pressure - and low amp draw
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An undercharged system+insufficient airflow over the evaporator coil

26. Which of the following can cause excessive subcooling...
Both technicians are incorrect
An overcharged system
Technician B
Low discharge pressure - high suction pressure - and low amp draw

27. Superheat is found in an air conditioning system in the...
Evaporator and compressor
An increase in suction pressure and an increase in discharge pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An uninsulated suction line and a restricted metering device

28. 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
Whenever necessary
The discharge pressure increases and the amperage increases
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The external equalizer could be plugged

29. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase of air leakage from ductwork
Broken rings+broken valves+seized bearings
An uninsulated TXV sensing bulb

30. The temperature range of the suction line from an air conditioning system should be...
Current in the compressor circuit
50-65
Technician B
It is used to control refrigerant pressure in the compressor crankcase

31. What problem can cause an increase of discharge pressure and an increase of suction pressure...
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
An overcharged system
Partially frosted evaporator and high superheat

32. 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
An overcharged system
3 psig
Technician B
A start capacitor and a solid-state relay

33. 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
It would cause the low-side pressure to decrease
Increases starting torque
Technician B
The sight glass is full of liquid+the sight glass is full of gas

34. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The oil pump pressure and the crankcase pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The superheat will increase and the low-side pressure will decrease

35. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
'G' to 'C'
Short cycling and insufficient dehumidification
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

36. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
High superheat and low discharge pressure
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B

37. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Both technicians are incorrect
The discharge pressure increases and the amperage increases

38. 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
Partially frosted evaporator and high superheat
Both technicians are incorrect
The low-side pressure will decrease and the evaporator coil will be partially frosted
Clean the condenser coil

39. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Evaporator and compressor
The superheat will increase and the low-side pressure will decrease
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

40. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
A restricted metering device
The discharge pressure increases and the amperage increases
Low voltage and a faulty start relay
A vacuum test+oil traces around fittings+soap bubble solution

41. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
An uninsulated TXV sensing bulb
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
110-120

42. What is the purpose of an EPR valve...
A missing air filter+improper rotation of the indoor blower+blower too small
Short cycling and insufficient dehumidification
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
50-65

43. 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 low refrigerant charge
The internal overload is opened
The external equalizer could be plugged

44. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Low voltage and a faulty start relay
An overcharged system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

45. Which of the following is a common cause of an excessively low superheat on a TXV system...
A sensing bulb improperly connected to the suction line
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The sensing bulb at a lower temperature than the valve body
Partially frosted evaporator and high superheat

46. A system that is operating with a clear sight glass shows...
Technician A
A vacuum test+oil traces around fittings+soap bubble solution
The sight glass is full of liquid+the sight glass is full of gas
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

47. 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
A sensing bulb improperly connected to the suction line
Technician B
'G' to 'C'

48. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Technician A
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Whenever necessary
110-120

49. 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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50. The temperature range of the suction line from an air conditioning system should be...
Rise more than normal
The low-side pressure will decrease and the evaporator coil will be partially frosted
50-65
The sensing bulb at a lower temperature than the valve body