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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 common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
An uninsulated TXV sensing bulb
Technician A is correct
Both technicians are incorrect

2. When using a vapor-charged TXV bulb - it is necessary to have...
A vacuum test+oil traces around fittings+soap bubble solution
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Low superheat
The sensing bulb at a lower temperature than the valve body

3. 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
'G' to 'C'
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Both technicians are correct

4. What causes the automatic expansion valve to close...
'G' to 'C'
The sight glass is full of liquid+the sight glass is full of gas
An increase in low-side pressure
'G' to 'C'

5. What are two problems that can cause an air conditioning system to have an excessively high superheat...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
50-65
An uninsulated suction line and a restricted metering device

6. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
('Y' and 'C') and ('G' and 'C')
A low refrigerant charge
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
'G' to 'C'

7. 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
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
The external equalizer could be plugged

8. Insufficient airflow can be caused by...
An increase in low-side pressure
Both technicians are incorrect
Flooding the condenser - cycling condenser fans - and dampering condenser air
An increase of air leakage from ductwork

9. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
An increase of air leakage from ductwork
Technician B
A sensing bulb improperly connected to the suction line
A missing air filter+improper rotation of the indoor blower+blower too small

10. Which of the following can cause low superheat in a TXV system...
A restricted metering device
An uninsulated TXV sensing bulb
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The superheat will increase and the low-side pressure will decrease

11. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
20 to 30
The oil pump pressure and the crankcase pressure

12. 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...
The internal overload is opened
Lack of airflow
A blown fuse
Technician B

13. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The sensing bulb at a lower temperature than the valve body
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Low discharge pressure - high suction pressure - and low amp draw
50-65

14. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
A start capacitor and a solid-state relay
An increase of air leakage from ductwork
Run with high head and high suction pressure

15. Why is it unsafe to operate an air conditioning system with a low charge...
110-120
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
The sensing bulb at a lower temperature than the valve body

16. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
It would cause the low-side pressure to decrease
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A plugged filter drier

17. What is the purpose of the TXV...
Rise more than normal
It keeps a constant superheat in the evaporator
The internal overload is opened
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

18. 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
An overcharged system
Current in the compressor circuit
An uninsulated TXV sensing bulb
Technician B

19. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
110-120
An acid-core suction line drier
Both technicians are correct
The superheat will increase and the low-side pressure will decrease

20. 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
Lack of airflow
20 to 30
Technician B

21. What are two problems that can cause an air conditioning system to have an excessively high superheat...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An uninsulated suction line and a restricted metering device
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

22. 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...
The internal overload is opened
Lack of airflow
50-65
3 psig

23. A system that uses a thermal electric expansion valve...
The superheat will increase and the low-side pressure will decrease
The internal overload is opened
Whenever necessary
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

24. What is the common cause of a compressor burnout...
An undercharge and low ambient conditions
A sensing bulb improperly connected to the suction line
Contains a solenoid coil and one or more sets of contacts
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

25. 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 sensing bulb improperly connected to the suction line
Technician B
Broken rings+broken valves+seized bearings
Low voltage and a faulty start relay

26. What are two common symptoms of refrigerant leaks in an air conditioning system...
The superheat will increase and the low-side pressure will decrease
An overcharged system
Partially frosted evaporator and high superheat
('Y' and 'C') and ('G' and 'C')

27. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
The system has been overcharged+The system has air trapped in the condenser
Evaporator and compressor
High suction pressure and low superheat
('Y' and 'C') and ('G' and 'C')

28. What are two common symptoms of refrigerant leaks in an air conditioning system...
The system has been overcharged+The system has air trapped in the condenser
An overcharged system
Partially frosted evaporator and high superheat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

29. Air filters should be replaced...
Low discharge pressure - high suction pressure - and low amp draw
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Whenever necessary
Technician B

30. What are common methods that are used for leak-testing a system...
A missing air filter+improper rotation of the indoor blower+blower too small
A vacuum test+oil traces around fittings+soap bubble solution
'G' to 'C'
Technician A

31. A customer calls with an insufficient cooling complaint on a 90
A plugged filter drier
Technician B
Contains a solenoid coil and one or more sets of contacts
An undercharged system+insufficient airflow over the evaporator coil

32. 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
Technician B
The internal overload is opened
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The external equalizer could be plugged

33. A 220-volt 30-amp motor circuit keeps tripping the breaker after the motor is started. The starting amperage is 60 amps. When measuring the amperage of the circuit - This is drawn for a brief moment. After startup - the amperage drops to 22 amps and
Low discharge pressure - high suction pressure - and low amp draw
A defective circuit breaker
The external equalizer could be plugged
High suction pressure and low superheat

34. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The sensing bulb at a lower temperature than the valve body
Technician B

35. A liquid-charged TXV bulb will...
Partially frosted evaporator and high superheat
A sensing bulb improperly connected to the suction line
An acid-core suction line drier
Always have some liquid present in the bulb and diaphragm

36. What three things can prevent an air conditioning system from releasing heat at the proper rate...
50-65
High superheat and low discharge pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in low-side pressure

37. A compressor having tight bearings would cause the current value to...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A restricted metering device
Rise more than normal
Technician B

38. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A restricted metering device
An increase of air leakage from ductwork
Always have some liquid present in the bulb and diaphragm
A dirty condenser - recirculation of condenser air - and a defective condenser fan

39. 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
A start relay
A defective circuit breaker
The sight glass is full of liquid+the sight glass is full of gas

40. 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
Both technicians are incorrect
Technician B
Partially frosted evaporator and high superheat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

41. The best description of a relay would be...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A start relay
Contains a solenoid coil and one or more sets of contacts

42. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
An increase in low-side pressure
Low discharge pressure - high suction pressure - and low amp draw
Bad compressor valve

43. 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...
It would cause the low-side pressure to decrease
3 psig
High superheat and low discharge pressure
It keeps a constant superheat in the evaporator

44. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
Short cycling and insufficient dehumidification
Both technicians are incorrect
Clean the condenser coil
Technician B

45. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
An uninsulated TXV sensing bulb
20 to 30
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Dirty condenser - bent condenser fins - and air recirculating over the condenser

46. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An undercharged system+insufficient airflow over the evaporator coil
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A start relay
A missing air filter+improper rotation of the indoor blower+blower too small

47. Insufficient airflow can be caused by...
('Y' and 'C') and ('G' and 'C')
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
An increase of air leakage from ductwork

48. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Lack of airflow
The sensing bulb at a lower temperature than the valve body

49. What are the symptoms of a TXV air conditioning system if it has lost its charge...
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
The superheat will increase and the low-side pressure will decrease
Run with high head and high suction pressure

50. What are the symptoms of an air conditioning system that has a low charge...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An undercharge and low ambient conditions
It keeps a constant superheat in the evaporator
The low-side pressure will decrease and the evaporator coil will be partially frosted

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NATE Air Conditioning Troubleshooting

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