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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. 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
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
High suction pressure and low superheat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

2. A party-store owner tried to adjust the water valve on his water-cooled condensing unit - then he called for assistance from an HVAC/are service technician. It was found that when servicing the unit - the outlet water temperature was too low. Technic
The superheat increases and the subcooling decreases
The superheat will increase and the low-side pressure will decrease
Technician B
A blown fuse

3. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
3 psig
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

4. Why is it unsafe to operate an air conditioning system with a low charge...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The internal overload is opened
20 to 30
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

5. 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
Bad compressor valve
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Short cycling and insufficient dehumidification
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

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

7. 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
Broken rings+broken valves+seized bearings
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The system has been overcharged+The system has air trapped in the condenser

8. A customer calls to complain that his central air conditioning system is not cooling properly. The technician arrives on the job. He or she notices that the indoor blower has adequate airflow and the outdoor condenser fan is operating - but the compr
An open internal overload protector
Whenever necessary
The sensing bulb at a lower temperature than the valve body
A sensing bulb improperly connected to the suction line

9. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A plugged filter drier
An open internal overload protector
Both technicians are correct
A dirty condenser - recirculation of condenser air - and a defective condenser fan

10. A liquid-charged TXV bulb will...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Both technicians are incorrect
Always have some liquid present in the bulb and diaphragm
Low voltage and a faulty start relay

11. 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
The internal overload is opened
Technician B
Current in the compressor circuit
A missing air filter+improper rotation of the indoor blower+blower too small

12. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
A restricted metering device
A start relay
50-65

13. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Increases starting torque
Technician B
110-120
An acid-core suction line drier

14. Insufficient airflow can be caused by...
110-120
An increase in low-side pressure
An increase of air leakage from ductwork
An undercharged system+insufficient airflow over the evaporator coil

15. A customer calls to complain that his central air conditioning system is not cooling properly. The technician arrives on the job. He or she notices that the indoor blower has adequate airflow and the outdoor condenser fan is operating - but the compr
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
An open internal overload protector

16. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
An open internal overload protector
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

17. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Technician B
Broken rings+broken valves+seized bearings
Flooding the condenser - cycling condenser fans - and dampering condenser air
The sight glass is full of liquid+the sight glass is full of gas

18. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
110-120
Flooding the condenser - cycling condenser fans - and dampering condenser air
It is used to control refrigerant pressure in the compressor crankcase
Lack of airflow

19. 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
Both technicians are correct
Both technicians are incorrect
Evaporator and compressor
20 to 30

20. 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 missing air filter+improper rotation of the indoor blower+blower too small
Technician B
Current in the compressor circuit
The system has been overcharged+The system has air trapped in the condenser

21. 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
Bad compressor valve
A blown fuse
It would cause the low-side pressure to decrease
Both technicians are incorrect

22. What type of problems can be caused by an oversized air conditioning system...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Short cycling and insufficient dehumidification
An undercharged system+insufficient airflow over the evaporator coil
A blown fuse

23. 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
The sight glass is full of liquid+the sight glass is full of gas
A missing air filter+improper rotation of the indoor blower+blower too small
An uninsulated suction line and a restricted metering device

24. 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
Clean the condenser coil
A blown fuse
An increase of air leakage from ductwork
Technician B

25. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Technician B
An increase in suction pressure and an increase in discharge pressure
An overcharged system
Flooding the condenser - cycling condenser fans - and dampering condenser air

26. 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
Clean the condenser coil
It would cause the low-side pressure to decrease
An undercharged system+insufficient airflow over the evaporator coil

27. A system that is operating with a clear sight glass shows...
It keeps a constant superheat in the evaporator
The internal overload is opened
The sight glass is full of liquid+the sight glass is full of gas
A sensing bulb improperly connected to the suction line

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
Technician B
An uninsulated TXV sensing bulb
A start capacitor and a solid-state relay

29. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
110-120
'G' to 'C'
A restricted metering device

30. A system that uses a thermal electric expansion valve...
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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Increases starting torque

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. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An undercharged system+insufficient airflow over the evaporator coil
Flooding the condenser - cycling condenser fans - and dampering condenser air
An overcharged system
The superheat increases and the subcooling decreases

33. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
Clean the condenser coil
Technician B
Rise more than normal

34. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
The external equalizer could be plugged
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
20 to 30
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

35. 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
An increase of air leakage from ductwork
An overcharged system
An uninsulated suction line and a restricted metering device

36. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
It is used to control refrigerant pressure in the compressor crankcase
The internal overload is opened
Technician A is correct
The discharge pressure increases and the amperage increases

37. 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 undercharge and low ambient conditions
The low-side pressure will decrease and the evaporator coil will be partially frosted
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

38. A hard-start kit consists of...
Technician A is correct
An increase of air leakage from ductwork
A start capacitor and a solid-state relay
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

39. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician A is correct
The oil pump pressure and the crankcase pressure

40. What are the symptoms of an air conditioning system that has a low charge...
('Y' and 'C') and ('G' and 'C')
The low-side pressure will decrease and the evaporator coil will be partially frosted
An overcharged system
Run with high head and high suction pressure

41. Which of the following is a common cause of an excessively low superheat on a TXV system...
It is used to control refrigerant pressure in the compressor crankcase
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The discharge pressure increases and the amperage increases
A sensing bulb improperly connected to the suction line

42. 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 defective circuit breaker
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

43. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An undercharge and low ambient conditions
The discharge pressure increases and the amperage increases
Contains a solenoid coil and one or more sets of contacts

44. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
An increase in suction pressure and an increase in discharge pressure
A restricted metering device
Run with high head and high suction pressure

45. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The superheat increases and the subcooling decreases
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The superheat will increase and the low-side pressure will decrease
A low refrigerant charge

46. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
'G' to 'C'
Low discharge pressure - high suction pressure - and low amp draw
Technician B
The superheat will increase and the low-side pressure will decrease

47. 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
The low-side pressure will decrease and the evaporator coil will be partially frosted
High superheat and low discharge pressure
A start relay

48. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Increases starting torque
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician A is correct

49. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase of air leakage from ductwork
An increase in suction pressure and an increase in discharge pressure
'G' to 'C'
An undercharge and low ambient conditions

50. A commercial customer calls on a 90
The superheat increases and the subcooling decreases
An undercharged system+insufficient airflow over the evaporator coil
The system has been overcharged+The system has air trapped in the condenser
Technician B