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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 is the common cause of a compressor burnout...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician A
Low discharge pressure - high suction pressure - and low amp draw

2. Which of the following could be the cause for a system's discharge and suction pressure being low...
It would cause the low-side pressure to decrease
A missing air filter+improper rotation of the indoor blower+blower too small
A restricted metering device
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

3. 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
50-65
Increases starting torque

4. What type of problems can be caused by an oversized air conditioning system...
Both technicians are incorrect
Broken rings+broken valves+seized bearings
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Short cycling and insufficient dehumidification

5. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Technician B
High suction pressure and low superheat
A bad thermostat
A defective circuit breaker

6. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Both technicians are incorrect
Partially frosted evaporator and high superheat
An undercharge and low ambient conditions
High superheat and low discharge pressure

7. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Both technicians are correct
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
20 to 30

8. What are three methods for controlling a system's high-side pressure during low ambient conditions...
An uninsulated suction line and a restricted metering device
An undercharged system+insufficient airflow over the evaporator coil
Low superheat
Flooding the condenser - cycling condenser fans - and dampering condenser air

9. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Current in the compressor circuit
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A plugged filter drier
A dirty condenser - recirculation of condenser air - and a defective condenser fan

10. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Both technicians are correct
Low voltage and a faulty start relay
The superheat increases and the subcooling decreases
An uninsulated suction line and a restricted metering device

11. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
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
It would cause the low-side pressure to decrease
Technician A is correct

12. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
High superheat and low discharge pressure
Clean the condenser coil
The discharge pressure increases and the amperage increases

13. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
Evaporator and compressor
An undercharged system+insufficient airflow over the evaporator coil
A low refrigerant charge

14. When using a vapor-charged TXV bulb - it is necessary to have...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An uninsulated suction line and a restricted metering device
The sensing bulb at a lower temperature than the valve body
Bad compressor valve

15. 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
A plugged filter drier
Whenever necessary
Technician B
'G' to 'C'

16. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The discharge pressure increases and the amperage increases
Technician B
Partially frosted evaporator and high superheat

17. 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 external equalizer could be plugged
3 psig
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

18. 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
Rise more than normal
Contains a solenoid coil and one or more sets of contacts
3 psig

19. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A sensing bulb improperly connected to the suction line
An increase in suction pressure and an increase in discharge pressure
A start capacitor and a solid-state relay
It is used to control refrigerant pressure in the compressor crankcase

20. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
('Y' and 'C') and ('G' and 'C')
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

21. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are incorrect

22. Which of the following is a common cause of an excessively low superheat on a TXV system...
An increase in suction pressure and an increase in discharge pressure
It keeps a constant superheat in the evaporator
An increase of air leakage from ductwork
A sensing bulb improperly connected to the suction line

23. 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...
A restricted metering device
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure
The internal overload is opened

24. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Bad compressor valve
An overcharged system
Low superheat

25. 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
110-120
A restricted metering device
The external equalizer could be plugged
Evaporator and compressor

26. 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...

27. 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...
High superheat and low discharge pressure
An overcharged system
Technician A is correct
A vacuum test+oil traces around fittings+soap bubble solution

28. 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...
High superheat and low discharge pressure
Technician A
The internal overload is opened
An undercharge and low ambient conditions

29. 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 oil pump pressure and the crankcase pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
An increase in low-side pressure

30. 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...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The internal overload is opened
Evaporator and compressor
The system has been overcharged+The system has air trapped in the condenser

31. What is the purpose of an EPR valve...
A bad thermostat
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The sight glass is full of liquid+the sight glass is full of gas

32. What problem or problems can cause low discharge and suction pressure...
Current in the compressor circuit
An undercharged system+insufficient airflow over the evaporator coil
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

33. 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
Both technicians are correct
Technician A is correct
Short cycling and insufficient dehumidification
An acid-core suction line drier

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
Evaporator and compressor
An increase of air leakage from ductwork
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

35. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Whenever necessary
It would cause the low-side pressure to decrease
The internal overload is opened
A vacuum test+oil traces around fittings+soap bubble solution

36. 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
Technician B
A defective circuit breaker
Always have some liquid present in the bulb and diaphragm
Both technicians are incorrect

37. What causes the automatic expansion valve to close...
An uninsulated suction line and a restricted metering device
Short cycling and insufficient dehumidification
An increase in low-side pressure
3 psig

38. Why is it unsafe to operate an air conditioning system with a low charge...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
50-65
A low refrigerant charge
Lack of airflow

39. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An undercharged system+insufficient airflow over the evaporator coil
The external equalizer could be plugged

40. 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
A bad thermostat
Both technicians are correct
'G' to 'C'
Evaporator and compressor

41. 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
A bad thermostat
The sensing bulb at a lower temperature than the valve body
Both technicians are incorrect
Lack of airflow

42. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
Increases starting torque
Technician A is correct
An increase in low-side pressure

43. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The system has been overcharged+The system has air trapped in the condenser
20 to 30
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It keeps a constant superheat in the evaporator

44. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
An acid-core suction line drier

45. 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
Lack of airflow
A sensing bulb improperly connected to the suction line
Rise more than normal
Broken rings+broken valves+seized bearings

46. What component is most often the cause of a start capacitor failure...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A start relay
Clean the condenser coil

47. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
A vacuum test+oil traces around fittings+soap bubble solution
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician A is correct

48. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
An uninsulated suction line and a restricted metering device
It would cause the low-side pressure to decrease
An overcharged system
A start relay

49. A hard-start kit for an air conditioning system...
Increases starting torque
A start capacitor and a solid-state relay
20 to 30
Both technicians are incorrect

50. A compressor motor starts and operates for a short period of time and cycles on the external overload protector. What are two possible problems that could cause this...
An increase in suction pressure and an increase in discharge pressure
Low voltage and a faulty start relay
An overcharged system
A sensing bulb improperly connected to the suction line