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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 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
Technician B
Current in the compressor circuit
It would cause the low-side pressure to decrease

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
An undercharged system+insufficient airflow over the evaporator coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Broken rings+broken valves+seized bearings
Technician A

3. 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
Technician B
It would cause the low-side pressure to decrease
Both technicians are incorrect
Technician B

4. Why is it unsafe to operate an air conditioning system with a low charge...
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
20 to 30
Technician B

5. An air conditioning system that uses a fan center has an inoperable indoor blower. When the thermostat is set for cooling and dialed below room temperature - a test with the voltmeter shows that there is 24 volts across terminals 'are' and 'G' at the
An uninsulated TXV sensing bulb
A missing air filter+improper rotation of the indoor blower+blower too small
A bad thermostat
It is used to control refrigerant pressure in the compressor crankcase

6. What component is most often the cause of a start capacitor failure...
The superheat will increase and the low-side pressure will decrease
Technician A
An increase of air leakage from ductwork
A start relay

7. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
A defective circuit breaker
A defective circuit breaker
A sensing bulb improperly connected to the suction line

8. A hard-start kit consists of...
Clean the condenser coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The oil pump pressure and the crankcase pressure
A start capacitor and a solid-state relay

9. If 24 volts are present to the contactor coil on an air conditioning system and the condenser fan or compressor is inoperative - which of the following could be at fault...
A blown fuse
Whenever necessary
The low-side pressure will decrease and the evaporator coil will be partially frosted
Broken rings+broken valves+seized bearings

10. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An increase in low-side pressure
The superheat increases and the subcooling decreases
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The discharge pressure increases and the amperage increases

11. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
50-65
A defective circuit breaker
An increase in suction pressure and an increase in discharge pressure

12. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Low superheat
An open internal overload protector
An increase in suction pressure and an increase in discharge pressure
Technician A is correct

13. When using a vapor-charged TXV bulb - it is necessary to have...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
3 psig
High suction pressure and low superheat
The sensing bulb at a lower temperature than the valve body

14. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
An undercharge and low ambient conditions
An increase of air leakage from ductwork

15. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Short cycling and insufficient dehumidification
Low discharge pressure - high suction pressure - and low amp draw
A defective circuit breaker
The superheat increases and the subcooling decreases

16. 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
Low superheat
Low discharge pressure - high suction pressure - and low amp draw
50-65
Technician B

17. A liquid-charged TXV bulb will...
Lack of airflow
A plugged filter drier
Always have some liquid present in the bulb and diaphragm
Both technicians are correct

18. What is the purpose of the TXV...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An open internal overload protector
Condenser fans operating during a low ambient condition and a low suction pressure
It keeps a constant superheat in the evaporator

19. 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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20. Which of the following is a common cause of an excessively low superheat on a TXV system...
Low superheat
A sensing bulb improperly connected to the suction line
A start relay
High suction pressure and low superheat

21. 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
110-120
3 psig
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

22. 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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23. 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
High suction pressure and low superheat
An open internal overload protector
50-65
The external equalizer could be plugged

24. Which of the following can cause excessive subcooling...
Low voltage and a faulty start relay
An overcharged system
The oil pump pressure and the crankcase pressure
The sensing bulb at a lower temperature than the valve body

25. Why is it unsafe to operate an air conditioning system with a low charge...
Both technicians are incorrect
The system has been overcharged+The system has air trapped in the condenser
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An overcharged system

26. When using a vapor-charged TXV bulb - it is necessary to have...
Always have some liquid present in the bulb and diaphragm
It is used to control refrigerant pressure in the compressor crankcase
A restricted metering device
The sensing bulb at a lower temperature than the valve body

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
The internal overload is opened
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An overcharged system

28. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Technician B
The superheat will increase and the low-side pressure will decrease
20 to 30
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

29. 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
Partially frosted evaporator and high superheat
It would cause the low-side pressure to decrease
An open internal overload protector
Contains a solenoid coil and one or more sets of contacts

30. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A blown fuse
An open internal overload protector
Run with high head and high suction pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser

31. A commercial customer calls on a 90
The internal overload is opened
The system has been overcharged+The system has air trapped in the condenser
Condenser fans operating during a low ambient condition and a low suction pressure
110-120

32. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A plugged filter drier
A vacuum test+oil traces around fittings+soap bubble solution
It is used to control refrigerant pressure in the compressor crankcase

33. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
The superheat increases and the subcooling decreases
Lack of airflow
Both technicians are incorrect
Low discharge pressure - high suction pressure - and low amp draw

34. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Condenser fans operating during a low ambient condition and a low suction pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
High suction pressure and low superheat

35. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Lack of airflow
Technician A
3 psig

36. What is the common cause of a compressor burnout...
A plugged filter drier
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The external equalizer could be plugged

37. The temperature range of the suction line from an air conditioning system should be...
Technician A
50-65
Broken rings+broken valves+seized bearings
Bad compressor valve

38. Which of the following will cause excessive discharge pressures on an air conditioning 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
Contains a solenoid coil and one or more sets of contacts
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

39. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Technician A
Technician B
The internal overload is opened
Bad compressor valve

40. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Both technicians are incorrect
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Dirty condenser - bent condenser fins - and air recirculating over the condenser

41. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Condenser fans operating during a low ambient condition and a low suction pressure
Always have some liquid present in the bulb and diaphragm
A dirty condenser - recirculation of condenser air - and a defective condenser fan
20 to 30

42. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
20 to 30
An uninsulated suction line and a restricted metering device
The superheat increases and the subcooling decreases

43. 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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44. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Low voltage and a faulty start relay
A start capacitor and a solid-state relay
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Partially frosted evaporator and high superheat

45. 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
3 psig
Both technicians are correct
Low voltage and a faulty start relay
An acid-core suction line drier

46. Which of the following is a common cause of an excessively low superheat on a TXV system...
Contains a solenoid coil and one or more sets of contacts
A sensing bulb improperly connected to the suction line
The low-side pressure will decrease and the evaporator coil will be partially frosted
The system has been overcharged+The system has air trapped in the condenser

47. 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
It is used to control refrigerant pressure in the compressor crankcase
It keeps a constant superheat in the evaporator
The superheat increases and the subcooling decreases

48. 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...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The internal overload is opened
High superheat and low discharge pressure
An open internal overload protector

49. The temperature range of the suction line from an air conditioning system should be...
A blown fuse
The sight glass is full of liquid+the sight glass is full of gas
Contains a solenoid coil and one or more sets of contacts
50-65

50. 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
The low-side pressure will decrease and the evaporator coil will be partially frosted
A missing air filter+improper rotation of the indoor blower+blower too small
An increase in low-side pressure