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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. When using a vapor-charged TXV bulb - it is necessary to have...
The superheat increases and the subcooling decreases
The sensing bulb at a lower temperature than the valve body
50-65
Technician B

2. The temperature range of the suction line from an air conditioning system should be...
Current in the compressor circuit
The superheat will increase and the low-side pressure will decrease
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
50-65

3. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A plugged filter drier
An increase in suction pressure and an increase in discharge pressure

4. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
The superheat increases and the subcooling decreases
50-65
An increase in suction pressure and an increase in discharge pressure

5. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
An acid-core suction line drier
Technician B

6. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
The superheat will increase and the low-side pressure will decrease
An undercharged system+insufficient airflow over the evaporator coil
Run with high head and high suction pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air

7. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An overcharged system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The discharge pressure increases and the amperage increases
Always have some liquid present in the bulb and diaphragm

8. What causes the automatic expansion valve to close...
An increase in low-side pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Bad compressor valve
Increases starting torque

9. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician A
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

10. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Short cycling and insufficient dehumidification
Both technicians are incorrect
A low refrigerant charge
It would cause the low-side pressure to decrease

11. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
An increase in low-side pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

12. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Technician B
Clean the condenser coil
Flooding the condenser - cycling condenser fans - and dampering condenser air
Condenser fans operating during a low ambient condition and a low suction pressure

13. What are two common symptoms of refrigerant leaks in an air conditioning system...
Lack of airflow
Partially frosted evaporator and high superheat
3 psig
Evaporator and compressor

14. 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...
Low voltage and a faulty start relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An overcharged system
An undercharge and low ambient conditions

15. What is the purpose of a CPR valve...
Whenever necessary
The superheat will increase and the low-side pressure will decrease
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It is used to control refrigerant pressure in the compressor crankcase

16. What type of problems can be caused by an oversized air conditioning system...
It would cause the low-side pressure to decrease
Broken rings+broken valves+seized bearings
Short cycling and insufficient dehumidification
Technician B

17. Which of the following could be the cause for a system's discharge and suction pressure being low...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A restricted metering device
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A blown fuse

18. Which of the following will cause excessive discharge pressures on an air conditioning system...
Clean the condenser coil
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
('Y' and 'C') and ('G' and 'C')
An overcharged system

19. 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...
Both technicians are incorrect
The internal overload is opened
A defective circuit breaker
Evaporator and compressor

20. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An open internal overload protector
Clean the condenser coil
Both technicians are incorrect

21. 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
A restricted metering device
The external equalizer could be plugged
Technician B
An undercharged system+insufficient airflow over the evaporator coil

22. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Bad compressor valve
The superheat increases and the subcooling decreases
The internal overload is opened
Increases starting torque

23. Which of the following can cause excessive subcooling...
An undercharged system+insufficient airflow over the evaporator coil
Rise more than normal
High superheat and low discharge pressure
An overcharged system

24. 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
Both technicians are correct
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Low superheat

25. A hard-start kit consists of...
An acid-core suction line drier
Both technicians are incorrect
A sensing bulb improperly connected to the suction line
A start capacitor and a solid-state relay

26. What component is most often the cause of a start capacitor failure...
A start relay
An undercharged system+insufficient airflow over the evaporator coil
Bad compressor valve
A low refrigerant charge

27. 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
Technician A
Partially frosted evaporator and high superheat
Both technicians are incorrect
Lack of airflow

28. 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
High superheat and low discharge pressure
The external equalizer could be plugged
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B

29. What are the symptoms of a TXV air conditioning system if it has lost its charge...
An increase in suction pressure and an increase in discharge pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A plugged filter drier
The superheat will increase and the low-side pressure will decrease

30. A system that uses a thermal electric expansion valve...
An open internal overload protector
Broken rings+broken valves+seized bearings
The sight glass is full of liquid+the sight glass is full of gas
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

31. What problem can cause an increase of discharge pressure and an increase of suction pressure...
High suction pressure and low superheat
It keeps a constant superheat in the evaporator
It keeps a constant superheat in the evaporator
An overcharged system

32. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
3 psig
A start capacitor and a solid-state relay
Technician B

33. What are the operating pressures of an oil pressure safety switch...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It would cause the low-side pressure to decrease
A start relay
The oil pump pressure and the crankcase pressure

34. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Condenser fans operating during a low ambient condition and a low suction pressure
A missing air filter+improper rotation of the indoor blower+blower too small
Both technicians are correct

35. Which of the following can cause low superheat in a TXV system...
Technician B
An uninsulated TXV sensing bulb
The superheat will increase and the low-side pressure will decrease
An undercharge and low ambient conditions

36. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B
An uninsulated TXV sensing bulb

37. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
Evaporator and compressor
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

38. What are the symptoms of a TXV air conditioning system if it has lost its charge...
'G' to 'C'
The superheat will increase and the low-side pressure will decrease
Short cycling and insufficient dehumidification
Run with high head and high suction pressure

39. What are the operating pressures of an oil pressure safety switch...
Technician B
Contains a solenoid coil and one or more sets of contacts
The oil pump pressure and the crankcase pressure
An undercharged system+insufficient airflow over the evaporator coil

40. What type of problems can be caused by an oversized air conditioning system...
The oil pump pressure and the crankcase pressure
High superheat and low discharge pressure
Whenever necessary
Short cycling and insufficient dehumidification

41. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Broken rings+broken valves+seized bearings
The oil pump pressure and the crankcase pressure
Bad compressor valve
Low superheat

42. What are three methods for controlling a system's high-side pressure during low ambient conditions...
The superheat increases and the subcooling decreases
An uninsulated suction line and a restricted metering device
Low voltage and a faulty start relay
Flooding the condenser - cycling condenser fans - and dampering condenser air

43. The temperature range of the suction line from an air conditioning system should be...
Rise more than normal
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Condenser fans operating during a low ambient condition and a low suction pressure
50-65

44. Why is it unsafe to operate an air conditioning system with a low charge...
3 psig
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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

45. A compressor having tight bearings would cause the current value to...
The system has been overcharged+The system has air trapped in the condenser
The sensing bulb at a lower temperature than the valve body
Technician B
Rise more than normal

46. A restricted air filter in an air conditioning system can be identified by...
An increase in low-side pressure
A low refrigerant charge
Low superheat
High superheat and low discharge pressure

47. 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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48. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
It keeps a constant superheat in the evaporator
Lack of airflow
High superheat and low discharge pressure

49. 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...
Always have some liquid present in the bulb and diaphragm
High superheat and low discharge pressure
Clean the condenser coil
'G' to 'C'

50. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase of air leakage from ductwork
An undercharge and low ambient conditions