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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 controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Rise more than normal
A blown fuse
The internal overload is opened
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

2. 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
Technician B
An increase of air leakage from ductwork
An uninsulated TXV sensing bulb
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

3. What is the purpose of a CPR valve...
Short cycling and insufficient dehumidification
It is used to control refrigerant pressure in the compressor crankcase
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Low voltage and a faulty start relay

4. What causes the automatic expansion valve to close...
Whenever necessary
An increase in low-side pressure
Partially frosted evaporator and high superheat
Short cycling and insufficient dehumidification

5. What problem or problems can cause low discharge and suction pressure...
The sight glass is full of liquid+the sight glass is full of gas
20 to 30
An undercharged system+insufficient airflow over the evaporator coil
A sensing bulb improperly connected to the suction line

6. 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...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Evaporator and compressor
Low voltage and a faulty start relay
Clean the condenser coil

7. Superheat is found in an air conditioning system in the...
50-65
Evaporator and compressor
The sight glass is full of liquid+the sight glass is full of gas
Both technicians are incorrect

8. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A missing air filter+improper rotation of the indoor blower+blower too small
A plugged filter drier
Flooding the condenser - cycling condenser fans - and dampering condenser air
High suction pressure and low superheat

9. A system that uses a thermal electric expansion valve...
An increase in low-side pressure
A restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B

10. 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
The superheat will increase and the low-side pressure will decrease
A missing air filter+improper rotation of the indoor blower+blower too small
('Y' and 'C') and ('G' and 'C')

11. What are the symptoms of an air conditioning system that has a low charge...
A defective circuit breaker
A start capacitor and a solid-state relay
Contains a solenoid coil and one or more sets of contacts
The low-side pressure will decrease and the evaporator coil will be partially frosted

12. A hard-start kit consists of...
Run with high head and high suction pressure
Technician B
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

13. When using a vapor-charged TXV bulb - it is necessary to have...
An acid-core suction line drier
The sensing bulb at a lower temperature than the valve body
Technician B
Technician A

14. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
Current in the compressor circuit
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Partially frosted evaporator and high superheat

15. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The internal overload is opened
Lack of airflow
'G' to 'C'

16. Which of the following can cause low superheat in a TXV system...
High superheat and low discharge pressure
('Y' and 'C') and ('G' and 'C')
An acid-core suction line drier
An uninsulated TXV sensing bulb

17. Insufficient airflow can be caused by...
Partially frosted evaporator and high superheat
The sensing bulb at a lower temperature than the valve body
An increase in low-side pressure
An increase of air leakage from ductwork

18. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
A restricted metering device
Technician B
Technician B

19. Which of the following will cause excessive discharge pressures on an air conditioning system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician A
The sensing bulb at a lower temperature than the valve body
Dirty condenser - bent condenser fins - and air recirculating over the condenser

20. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

21. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
It would cause the low-side pressure to decrease
An uninsulated suction line and a restricted metering device
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

22. What causes the automatic expansion valve to close...
An increase in low-side pressure
Increases starting torque
Technician B
'G' to 'C'

23. Which of the following is a common cause of an excessively low superheat on a TXV system...
High suction pressure and low superheat
Low voltage and a faulty start relay
A sensing bulb improperly connected to the suction line
Broken rings+broken valves+seized bearings

24. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
An increase in low-side pressure
Run with high head and high suction pressure
High superheat and low discharge pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

25. What is the common cause of a compressor burnout...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Low discharge pressure - high suction pressure - and low amp draw
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

26. A liquid-charged TXV bulb will...
The external equalizer could be plugged
Technician B
Always have some liquid present in the bulb and diaphragm
An increase in suction pressure and an increase in discharge pressure

27. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated suction line and a restricted metering device
A start relay
A plugged filter drier
The superheat increases and the subcooling decreases

28. 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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29. The best description of a relay would be...
It keeps a constant superheat in the evaporator
Contains a solenoid coil and one or more sets of contacts
110-120
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

30. What problem or problems can cause low discharge and suction pressure...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An open internal overload protector
The superheat increases and the subcooling decreases
An undercharged system+insufficient airflow over the evaporator coil

31. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
An overcharged system
Partially frosted evaporator and high superheat
('Y' and 'C') and ('G' and 'C')

32. What type of problems can be caused by an oversized air conditioning system...
Whenever necessary
Short cycling and insufficient dehumidification
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The sensing bulb at a lower temperature than the valve body

33. 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...
A blown fuse
Condenser fans operating during a low ambient condition and a low suction pressure
Technician A
Low voltage and a faulty start relay

34. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An uninsulated TXV sensing bulb
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A missing air filter+improper rotation of the indoor blower+blower too small

35. 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
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
A low refrigerant charge
Clean the condenser coil

36. 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 vacuum test+oil traces around fittings+soap bubble solution
Both technicians are incorrect
Technician B
20 to 30

37. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Always have some liquid present in the bulb and diaphragm
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It is used to control refrigerant pressure in the compressor crankcase
An undercharge and low ambient conditions

38. What is the purpose of an EPR valve...
The oil pump pressure and the crankcase pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
A defective circuit breaker
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

39. What is the common cause of a compressor burnout...
50-65
Always have some liquid present in the bulb and diaphragm
An uninsulated TXV sensing bulb
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

40. 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...
'G' to 'C'
An undercharged system+insufficient airflow over the evaporator coil
High superheat and low discharge pressure
An increase in suction pressure and an increase in discharge pressure

41. A restricted air filter in an air conditioning system can be identified by...
The sensing bulb at a lower temperature than the valve body
Low superheat
An overcharged system
50-65

42. 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
110-120
The sight glass is full of liquid+the sight glass is full of gas
Technician B
Run with high head and high suction pressure

43. What component is most often the cause of a start capacitor failure...
The superheat will increase and the low-side pressure will decrease
A start relay
It is used to control refrigerant pressure in the compressor crankcase
A sensing bulb improperly connected to the suction line

44. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The sensing bulb at a lower temperature than the valve body
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

45. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A vacuum test+oil traces around fittings+soap bubble solution
Whenever necessary
110-120
Run with high head and high suction pressure

46. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
Both technicians are correct
A start capacitor and a solid-state relay
A blown fuse

47. 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
Technician A is correct
A sensing bulb improperly connected to the suction line
Both technicians are incorrect

48. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
The discharge pressure increases and the amperage increases
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Short cycling and insufficient dehumidification

49. Which of the following can cause excessive subcooling...
Short cycling and insufficient dehumidification
The sight glass is full of liquid+the sight glass is full of gas
An overcharged system
Technician B

50. A liquid-charged TXV bulb will...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Always have some liquid present in the bulb and diaphragm
Technician A is correct
Technician B