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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 problem or problems can cause low discharge and suction pressure...
An increase of air leakage from ductwork
Technician B
Both technicians are correct
An undercharged system+insufficient airflow over the evaporator coil

2. 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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Low discharge pressure - high suction pressure - and low amp draw
It would cause the low-side pressure to decrease

3. Which of the following can cause excessive subcooling...
The internal overload is opened
An overcharged system
A sensing bulb improperly connected to the suction line
The low-side pressure will decrease and the evaporator coil will be partially frosted

4. What are two common symptoms of refrigerant leaks in an air conditioning system...
Low discharge pressure - high suction pressure - and low amp draw
Partially frosted evaporator and high superheat
An increase in low-side pressure
A start capacitor and a solid-state relay

5. 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
An undercharged system+insufficient airflow over the evaporator coil
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Both technicians are incorrect

6. 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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7. 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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8. What problem or problems can cause low discharge and suction pressure...
A missing air filter+improper rotation of the indoor blower+blower too small
The discharge pressure increases and the amperage increases
A bad thermostat
An undercharged system+insufficient airflow over the evaporator coil

9. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Technician B
('Y' and 'C') and ('G' and 'C')
Low voltage and a faulty start relay
A plugged filter drier

10. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Run with high head and high suction pressure
The oil pump pressure and the crankcase pressure
A vacuum test+oil traces around fittings+soap bubble solution

11. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A vacuum test+oil traces around fittings+soap bubble solution
An overcharged system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
'G' to 'C'

12. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
Contains a solenoid coil and one or more sets of contacts
An increase in low-side pressure
A sensing bulb improperly connected to the suction line

13. 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
An open internal overload protector
Both technicians are incorrect
Flooding the condenser - cycling condenser fans - and dampering condenser air
Condenser fans operating during a low ambient condition and a low suction pressure

14. What component is most often the cause of a start capacitor failure...
An increase in low-side pressure
A start relay
Both technicians are incorrect
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

15. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician B
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
'G' to 'C'

16. 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
High suction pressure and low superheat
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

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
A sensing bulb improperly connected to the suction line
Bad compressor valve
Technician B
High suction pressure and low superheat

18. When using a vapor-charged TXV bulb - it is necessary to have...
The superheat will increase and the low-side pressure will decrease
Bad compressor valve
The discharge pressure increases and the amperage increases
The sensing bulb at a lower temperature than the valve body

19. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
A vacuum test+oil traces around fittings+soap bubble solution
Whenever necessary
Run with high head and high suction pressure

20. 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
110-120
Clean the condenser coil
A blown fuse
Broken rings+broken valves+seized bearings

21. A hard-start kit consists of...
The internal overload is opened
A start capacitor and a solid-state relay
Low voltage and a faulty start relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

22. 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 capacitor and a solid-state relay
The superheat increases and the subcooling decreases
An overcharged system

23. Air filters should be replaced...
Whenever necessary
('Y' and 'C') and ('G' and 'C')
Both technicians are incorrect
High superheat and low discharge pressure

24. Which of the following is a possible cause for a compressor to overheat...
Evaporator and compressor
A low refrigerant charge
Partially frosted evaporator and high superheat
Short cycling and insufficient dehumidification

25. A restricted air filter in an air conditioning system can be identified by...
The oil pump pressure and the crankcase pressure
It would cause the low-side pressure to decrease
Low superheat
An undercharged system+insufficient airflow over the evaporator coil

26. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
An uninsulated suction line and a restricted metering device
Both technicians are incorrect
An undercharged system+insufficient airflow over the evaporator coil

27. 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
Technician A
An increase in low-side pressure
It would cause the low-side pressure to decrease
Run with high head and high suction pressure

28. 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...
3 psig
High superheat and low discharge pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A defective circuit breaker

29. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A blown fuse
The superheat increases and the subcooling decreases
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Lack of airflow

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
Increases starting torque
Flooding the condenser - cycling condenser fans - and dampering condenser air
An increase of air leakage from ductwork
Both technicians are incorrect

31. 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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32. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Rise more than normal
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Flooding the condenser - cycling condenser fans - and dampering condenser air
The external equalizer could be plugged

33. A liquid-charged TXV bulb will...
A plugged filter drier
Always have some liquid present in the bulb and diaphragm
An undercharge and low ambient conditions
A vacuum test+oil traces around fittings+soap bubble solution

34. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An open internal overload protector
A missing air filter+improper rotation of the indoor blower+blower too small
50-65
Technician B

35. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
Lack of airflow
It would cause the low-side pressure to decrease
Technician B

36. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
An undercharged system+insufficient airflow over the evaporator coil
20 to 30
The discharge pressure increases and the amperage increases
3 psig

37. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Low voltage and a faulty start relay
Run with high head and high suction pressure
An open internal overload protector
The system has been overcharged+The system has air trapped in the condenser

38. 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 was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
The external equalizer could be plugged
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

39. What are the symptoms of an air conditioning system that has a low charge...
Run with high head and high suction pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
The superheat will increase and the low-side pressure will decrease
The oil pump pressure and the crankcase pressure

40. 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 start relay
Technician A is correct
20 to 30
Technician B

41. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
'G' to 'C'
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The system has been overcharged+The system has air trapped in the condenser

42. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Clean the condenser coil
An uninsulated suction line and a restricted metering device

43. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Contains a solenoid coil and one or more sets of contacts
Bad compressor valve
The sensing bulb at a lower temperature than the valve body
Low superheat

44. What are the symptoms of a TXV air conditioning system if it has lost its charge...
An acid-core suction line drier
The discharge pressure increases and the amperage increases
Contains a solenoid coil and one or more sets of contacts
The superheat will increase and the low-side pressure will decrease

45. Which of the following is a common cause of an excessively low superheat on a TXV system...
Both technicians are incorrect
Short cycling and insufficient dehumidification
A sensing bulb improperly connected to the suction line
A start relay

46. Superheat is found in an air conditioning system in the...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
'G' to 'C'
Evaporator and compressor

47. Which of the following will cause excessive discharge pressures on an air conditioning system...
An undercharged system+insufficient airflow over the evaporator coil
Current in the compressor circuit
A low refrigerant charge
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

48. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
110-120
Always have some liquid present in the bulb and diaphragm
A restricted metering device

49. 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...
Technician A is correct
An increase in suction pressure and an increase in discharge pressure
The internal overload is opened
Increases starting torque

50. Air filters should be replaced...
A sensing bulb improperly connected to the suction line
An uninsulated TXV sensing bulb
Lack of airflow
Whenever necessary