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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. 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
An increase in low-side pressure
Low discharge pressure - high suction pressure - and low amp draw
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

2. 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
Technician B
Bad compressor valve
The external equalizer could be plugged
A missing air filter+improper rotation of the indoor blower+blower too small

3. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Condenser fans operating during a low ambient condition and a low suction pressure
Increases starting torque
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty condenser - recirculation of condenser air - and a defective condenser fan

4. What are common methods that are used for leak-testing a system...
An acid-core suction line drier
A vacuum test+oil traces around fittings+soap bubble solution
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A blown fuse

5. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The superheat will increase and the low-side pressure will decrease
Technician B
Clean the condenser coil
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

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. A restricted air filter in an air conditioning system can be identified by...
('Y' and 'C') and ('G' and 'C')
Short cycling and insufficient dehumidification
Low superheat
A sensing bulb improperly connected to the suction line

8. What problem can cause an increase of discharge pressure and an increase of suction pressure...
The oil pump pressure and the crankcase pressure
An overcharged system
Rise more than normal
Bad compressor valve

9. What problem or problems can cause low discharge and suction pressure...
An increase of air leakage from ductwork
'G' to 'C'
Technician B
An undercharged system+insufficient airflow over the evaporator coil

10. 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...
('Y' and 'C') and ('G' and 'C')
Condenser fans operating during a low ambient condition and a low suction pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The oil pump pressure and the crankcase pressure

11. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An undercharged system+insufficient airflow over the evaporator coil
A bad thermostat

12. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
Always have some liquid present in the bulb and diaphragm
Contains a solenoid coil and one or more sets of contacts
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

13. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
3 psig
Lack of airflow
Clean the condenser coil
An uninsulated suction line and a restricted metering device

14. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
The external equalizer could be plugged
Bad compressor valve
Both technicians are incorrect
A plugged filter drier

15. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Low discharge pressure - high suction pressure - and low amp draw
A start relay
The superheat will increase and the low-side pressure will decrease
Evaporator and compressor

16. The temperature range of the suction line from an air conditioning system should be...
Both technicians are incorrect
50-65
Technician B
Run with high head and high suction pressure

17. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
('Y' and 'C') and ('G' and 'C')
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Rise more than normal

18. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Lack of airflow
An increase in suction pressure and an increase in discharge pressure
It keeps a constant superheat in the evaporator
Flooding the condenser - cycling condenser fans - and dampering condenser air

19. What causes the automatic expansion valve to close...
An increase in low-side pressure
The internal overload is opened
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
50-65

20. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
The system has been overcharged+The system has air trapped in the condenser
A low refrigerant charge
Rise more than normal

21. 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
The superheat increases and the subcooling decreases
Clean the condenser coil
It would cause the low-side pressure to decrease
Run with high head and high suction pressure

22. A system that uses a thermal electric expansion valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An overcharged system
The superheat will increase and the low-side pressure will decrease
Run with high head and high suction pressure

23. What are two common symptoms of refrigerant leaks in an air conditioning system...
An uninsulated TXV sensing bulb
Partially frosted evaporator and high superheat
Technician B
An uninsulated TXV sensing bulb

24. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
An undercharge and low ambient conditions

25. A restricted air filter in an air conditioning system can be identified by...
Always have some liquid present in the bulb and diaphragm
Low superheat
The system has been overcharged+The system has air trapped in the condenser
The discharge pressure increases and the amperage increases

26. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
A blown fuse
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

27. Which of the following can cause low superheat in a TXV system...
A sensing bulb improperly connected to the suction line
The external equalizer could be plugged
Technician B
An uninsulated TXV sensing bulb

28. 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 external equalizer could be plugged
Technician A
A bad thermostat

29. Which of the following can cause excessive subcooling...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An overcharged system
Technician B
'G' to 'C'

30. 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
Rise more than normal
Technician A is correct
Whenever necessary
It keeps a constant superheat in the evaporator

31. 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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32. What is the common cause of a compressor burnout...
Technician B
110-120
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
3 psig

33. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
Technician A is correct
3 psig
Contains a solenoid coil and one or more sets of contacts

34. Air filters should be replaced...
A defective circuit breaker
Whenever necessary
3 psig
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

35. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Rise more than normal
An acid-core suction line drier
A low refrigerant charge

36. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A sensing bulb improperly connected to the suction line
The superheat increases and the subcooling decreases
Technician A
Broken rings+broken valves+seized bearings

37. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An uninsulated TXV sensing bulb
Technician B
The oil pump pressure and the crankcase pressure

38. Why is it unsafe to operate an air conditioning system with a low charge...
Technician B
Both technicians are incorrect
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

39. Which of the following will cause excessive discharge pressures on an air conditioning system...
Lack of airflow
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The system has been overcharged+The system has air trapped in the condenser
Broken rings+broken valves+seized bearings

40. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
A start capacitor and a solid-state relay
Partially frosted evaporator and high superheat
It is used to control refrigerant pressure in the compressor crankcase

41. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The internal overload is opened
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
High superheat and low discharge pressure
Run with high head and high suction pressure

42. Air filters should be replaced...
Contains a solenoid coil and one or more sets of contacts
Run with high head and high suction pressure
Bad compressor valve
Whenever necessary

43. 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
Both technicians are correct
The sensing bulb at a lower temperature than the valve body
Technician B
An acid-core suction line drier

44. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Broken rings+broken valves+seized bearings
A start relay
Dirty condenser - bent condenser fins - and air recirculating over the condenser

45. 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...
The internal overload is opened
20 to 30
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A blown fuse

46. 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
Both technicians are incorrect
An overcharged system
An open internal overload protector
Technician B

47. 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
20 to 30
Technician B
Technician A is correct
Both technicians are incorrect

48. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
An increase of air leakage from ductwork
Low voltage and a faulty start relay
20 to 30

49. What three things can prevent an air conditioning system from releasing heat at the proper rate...
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 incorrect
It would cause the low-side pressure to decrease
A dirty condenser - recirculation of condenser air - and a defective condenser fan

50. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
A missing air filter+improper rotation of the indoor blower+blower too small
A restricted metering device
A plugged filter drier