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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 operating with a clear sight glass shows...
An uninsulated TXV sensing bulb
The sight glass is full of liquid+the sight glass is full of gas
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The system has been overcharged+The system has air trapped in the condenser

2. A restricted air filter in an air conditioning system can be identified by...
Low superheat
'G' to 'C'
An increase in low-side pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

3. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
Partially frosted evaporator and high superheat
Technician B
It is used to control refrigerant pressure in the compressor crankcase

4. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat will increase and the low-side pressure will decrease
A restricted metering device
A low refrigerant charge
The superheat increases and the subcooling decreases

5. Why is it unsafe to operate an air conditioning system with a low charge...
Increases starting torque
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An undercharge and low ambient conditions
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

6. A hard-start kit consists of...
A start capacitor and a solid-state relay
The internal overload is opened
It keeps a constant superheat in the evaporator
The superheat will increase and the low-side pressure will decrease

7. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Increases starting torque
An overcharged 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

8. 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
A blown fuse
It is used to control refrigerant pressure in the compressor crankcase
A missing air filter+improper rotation of the indoor blower+blower too small
Clean the condenser coil

9. A system that uses a thermal electric expansion valve...
Technician B
'G' to 'C'
('Y' and 'C') and ('G' and 'C')
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

10. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Rise more than normal
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An open internal overload protector
An increase in suction pressure and an increase in discharge pressure

11. Air filters should be replaced...
An uninsulated TXV sensing bulb
20 to 30
Low superheat
Whenever necessary

12. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
Partially frosted evaporator and high superheat
Clean the condenser coil
Contains a solenoid coil and one or more sets of contacts

13. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The discharge pressure increases and the amperage increases
The internal overload is opened
20 to 30
Bad compressor valve

14. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
An overcharged system
Technician A is correct
Technician B

15. The best description of a relay would be...
Short cycling and insufficient dehumidification
Contains a solenoid coil and one or more sets of contacts
Both technicians are incorrect
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

16. 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
An uninsulated suction line and a restricted metering device
The external equalizer could be plugged

17. 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 blown fuse
Whenever necessary
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician A is correct

18. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
An increase in suction pressure and an increase in discharge pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A plugged filter drier
Current in the compressor circuit

19. What are two common symptoms of refrigerant leaks in an air conditioning system...
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
Technician B
Partially frosted evaporator and high superheat

20. Which of the following can cause excessive subcooling...
A sensing bulb improperly connected to the suction line
The superheat increases and the subcooling decreases
Rise more than normal
An overcharged system

21. 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
Always have some liquid present in the bulb and diaphragm
A sensing bulb improperly connected to the suction line
An uninsulated suction line and a restricted metering device

22. A customer calls with an insufficient cooling complaint on a 90
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
Technician A is correct
A blown fuse

23. 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 overcharged system
Low discharge pressure - high suction pressure - and low amp draw
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

24. What problem or problems can cause low discharge and suction pressure...
Technician A is correct
A low refrigerant charge
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An undercharged system+insufficient airflow over the evaporator coil

25. 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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26. A compressor having tight bearings would cause the current value to...
Technician A is correct
It is used to control refrigerant pressure in the compressor crankcase
Rise more than normal
A restricted metering device

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
Bad compressor valve
Always have some liquid present in the bulb and diaphragm
A start relay

28. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Technician B
Rise more than normal
Contains a solenoid coil and one or more sets of contacts
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

29. The temperature range of the suction line from an air conditioning system should be...
Current in the compressor circuit
A dirty condenser - recirculation of condenser air - and a defective condenser fan
110-120
50-65

30. What are the operating pressures of an oil pressure safety switch...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The oil pump pressure and the crankcase pressure
Bad compressor valve
Bad compressor valve

31. A liquid-charged TXV bulb will...
110-120
Always have some liquid present in the bulb and diaphragm
Increases starting torque
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

32. A system that uses a thermal electric expansion valve...
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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A start capacitor and a solid-state relay

33. 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
An increase in low-side pressure
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are incorrect

34. 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
Technician B
Both technicians are correct
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
50-65

35. 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
Technician B
It keeps a constant superheat in the evaporator
Clean the condenser coil

36. What is the purpose of a CPR valve...
The system has been overcharged+The system has air trapped in the condenser
Technician B
It is used to control refrigerant pressure in the compressor crankcase
3 psig

37. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
The superheat will increase and the low-side pressure will decrease
An undercharge and low ambient conditions
The external equalizer could be plugged
The oil pump pressure and the crankcase pressure

38. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
An overcharged system
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An acid-core suction line drier

39. 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...
The internal overload is opened
A start capacitor and a solid-state relay
High superheat and low discharge pressure
Both technicians are incorrect

40. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small
An uninsulated suction line and a restricted metering device
An open internal overload protector

41. Which of the following can cause low superheat in a TXV system...
It would cause the low-side pressure to decrease
An uninsulated TXV sensing bulb
A missing air filter+improper rotation of the indoor blower+blower too small
An increase in suction pressure and an increase in discharge pressure

42. 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 sensing bulb at a lower temperature than the valve body
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Clean the condenser coil
('Y' and 'C') and ('G' and 'C')

43. Which of the following can cause low superheat in a TXV system...
The discharge pressure increases and the amperage increases
The sight glass is full of liquid+the sight glass is full of gas
Whenever necessary
An uninsulated TXV sensing bulb

44. 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 sight glass is full of liquid+the sight glass is full of gas
Both technicians are incorrect
Technician B
The system has been overcharged+The system has air trapped in the condenser

45. 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 in low-side pressure
An increase in suction pressure and an increase in discharge pressure
An acid-core suction line drier
The low-side pressure will decrease and the evaporator coil will be partially frosted

46. Superheat is found in an air conditioning system in the...
Technician B
A plugged filter drier
Evaporator and compressor
An increase of air leakage from ductwork

47. What component is most often the cause of a start capacitor failure...
Low discharge pressure - high suction pressure - and low amp draw
A start relay
Evaporator and compressor
The system has been overcharged+The system has air trapped in the condenser

48. 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
Both technicians are incorrect
Clean the condenser coil
Both technicians are correct
Flooding the condenser - cycling condenser fans - and dampering condenser air

49. A restricted air filter in an air conditioning system can be identified by...
Technician B
Low superheat
The external equalizer could be plugged
Clean the condenser coil

50. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An increase in suction pressure and an increase in discharge pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An undercharge and low ambient conditions
('Y' and 'C') and ('G' and 'C')