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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. The internal overload of an air conditioning compressor senses winding temperature and...
Both technicians are incorrect
Run with high head and high suction pressure
Contains a solenoid coil and one or more sets of contacts
Current in the compressor circuit

2. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
An increase in suction pressure and an increase in discharge pressure
Bad compressor valve
An open internal overload protector

3. What are common methods that are used for leak-testing a system...
Technician B
An overcharged system
A vacuum test+oil traces around fittings+soap bubble solution
A dirty condenser - recirculation of condenser air - and a defective condenser fan

4. Which of the following is a common cause of an excessively low superheat on a TXV system...
A bad thermostat
A sensing bulb improperly connected to the suction line
Technician B
The superheat increases and the subcooling decreases

5. 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
Low voltage and a faulty start relay
Technician B
An open internal overload protector
The oil pump pressure and the crankcase pressure

6. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
It would cause the low-side pressure to decrease
Both technicians are incorrect
The superheat increases and the subcooling decreases
Technician B

7. 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
Technician A is correct
High suction pressure and low superheat
('Y' and 'C') and ('G' and 'C')
Clean the condenser coil

8. 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 missing air filter+improper rotation of the indoor blower+blower too small
A blown fuse
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B

9. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The external equalizer could be plugged

10. 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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11. A commercial customer calls on a 90
It keeps a constant superheat in the evaporator
The system has been overcharged+The system has air trapped in the condenser
An acid-core suction line drier
High superheat and low discharge pressure

12. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Rise more than normal
Low voltage and a faulty start relay
An uninsulated suction line and a restricted metering device
Bad compressor valve

13. A customer calls with an insufficient cooling complaint on a 90
Technician B
Current in the compressor circuit
110-120
It keeps a constant superheat in the evaporator

14. Air filters should be replaced...
Whenever necessary
Both technicians are incorrect
Condenser fans operating during a low ambient condition and a low suction pressure
Clean the condenser coil

15. 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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16. 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
The superheat will increase and the low-side pressure will decrease
A restricted metering device
Technician B
Increases starting torque

17. 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...
Whenever necessary
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The internal overload is opened
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

18. What are two problems that can cause an air conditioning system to have an excessively high superheat...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An uninsulated suction line and a restricted metering device
Technician B
The superheat increases and the subcooling decreases

19. Superheat is found in an air conditioning system in the...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase of air leakage from ductwork
Evaporator and compressor
Contains a solenoid coil and one or more sets of contacts

20. What component is most often the cause of a start capacitor failure...
A start relay
The discharge pressure increases and the amperage increases
Clean the condenser coil
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

21. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
High suction pressure and low superheat
20 to 30
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are correct

22. 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 dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
Whenever necessary

23. 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 blown fuse
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Both technicians are incorrect

24. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An undercharge and low ambient conditions
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B

25. When using a vapor-charged TXV bulb - it is necessary to have...
An uninsulated suction line and a restricted metering device
Dirty condenser - bent condenser fins - and air recirculating over the condenser
'G' to 'C'
The sensing bulb at a lower temperature than the valve body

26. The temperature range of the suction line from an air conditioning system should be...
It is used to control refrigerant pressure in the compressor crankcase
The discharge pressure increases and the amperage increases
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
50-65

27. A compressor having tight bearings would cause the current value to...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Rise more than normal
Both technicians are incorrect
Evaporator and compressor

28. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
High suction pressure and low superheat
The external equalizer could be plugged
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

29. What are the symptoms of an air conditioning system that has a low charge...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Contains a solenoid coil and one or more sets of contacts
The internal overload is opened

30. 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
Both technicians are incorrect
The oil pump pressure and the crankcase pressure
Technician B
Technician B

31. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Always have some liquid present in the bulb and diaphragm
A low refrigerant charge
A bad thermostat
3 psig

32. 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 missing air filter+improper rotation of the indoor blower+blower too small
It is used to control refrigerant pressure in the compressor crankcase
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B

33. A system that uses a thermal electric expansion valve...
3 psig
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

34. 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
Contains a solenoid coil and one or more sets of contacts
A plugged filter drier
A bad thermostat
A missing air filter+improper rotation of the indoor blower+blower too small

35. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Run with high head and high suction pressure
Bad compressor valve
The superheat increases and the subcooling decreases
A start capacitor and a solid-state relay

36. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
An overcharged system

37. 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
Lack of airflow
An open internal overload protector
The superheat increases and the subcooling decreases
An increase of air leakage from ductwork

38. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Technician B
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An undercharge and low ambient conditions

39. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
50-65
('Y' and 'C') and ('G' and 'C')
Condenser fans operating during a low ambient condition and a low suction pressure

40. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Lack of airflow
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A bad thermostat
Both technicians are incorrect

41. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The external equalizer could be plugged
An acid-core suction line drier
The superheat increases and the subcooling decreases
A blown fuse

42. A commercial customer calls on a 90
('Y' and 'C') and ('G' and 'C')
The system has been overcharged+The system has air trapped in the condenser
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

43. 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 suction pressure and low superheat
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A bad thermostat
The internal overload is opened

44. 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
An increase in suction pressure and an increase in discharge pressure
The sensing bulb at a lower temperature than the valve body

45. Insufficient airflow can be caused by...
An uninsulated suction line and a restricted metering device
An increase of air leakage from ductwork
3 psig
A sensing bulb improperly connected to the suction line

46. 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...
Technician B
Low voltage and a faulty start relay
The low-side pressure will decrease and the evaporator coil will be partially frosted
The sight glass is full of liquid+the sight glass is full of gas

47. A hard-start kit consists of...
Run with high head and high suction pressure
A start capacitor and a solid-state relay
An overcharged system
The internal overload is opened

48. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A bad thermostat
Always have some liquid present in the bulb and diaphragm
An uninsulated suction line and a restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

49. 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
Both technicians are correct
Clean the condenser coil
A restricted metering device
Technician A

50. What causes the automatic expansion valve to close...
Whenever necessary
Rise more than normal
Technician B
An increase in low-side pressure