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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 dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A vacuum test+oil traces around fittings+soap bubble solution
A dirty condenser - recirculation of condenser air - and a defective condenser fan

2. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A low refrigerant charge
Run with high head and high suction pressure
A bad thermostat
Whenever necessary

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
A defective circuit breaker
Both technicians are incorrect
The external equalizer could be plugged
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

4. Which of the following will cause excessive discharge pressures on an air conditioning system...
A plugged filter drier
A plugged filter drier
Short cycling and insufficient dehumidification
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

5. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Current in the compressor circuit
Current in the compressor circuit
An increase in suction pressure and an increase in discharge pressure
An increase in low-side pressure

6. What three things can prevent an air conditioning system from releasing heat at the proper rate...
'G' to 'C'
An open internal overload protector
The discharge pressure increases and the amperage increases
A dirty condenser - recirculation of condenser air - and a defective condenser fan

7. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A sensing bulb improperly connected to the suction line
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Rise more than normal
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

8. 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
A bad thermostat
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An acid-core suction line drier

9. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Both technicians are incorrect
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B

10. A system that is operating with a clear sight glass shows...
A restricted metering device
Whenever necessary
The sight glass is full of liquid+the sight glass is full of gas
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

11. 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 sensing bulb at a lower temperature than the valve body
Low superheat
The external equalizer could be plugged
A vacuum test+oil traces around fittings+soap bubble solution

12. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
Technician B
The superheat increases and the subcooling decreases
An increase of air leakage from ductwork

13. What causes the automatic expansion valve to close...
The superheat increases and the subcooling decreases
An open internal overload protector
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in low-side pressure

14. A hard-start kit for an air conditioning system...
A restricted metering device
A bad thermostat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Increases starting torque

15. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
An uninsulated TXV sensing bulb
A plugged filter drier
Whenever necessary

16. A hard-start kit consists of...
Evaporator and compressor
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Lack of airflow
A start capacitor and a solid-state relay

17. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
20 to 30
High suction pressure and low superheat
The system has been overcharged+The system has air trapped in the condenser
The external equalizer could be plugged

18. Which of the following is a common cause of an excessively low superheat on a TXV system...
Technician A
Low voltage and a faulty start relay
110-120
A sensing bulb improperly connected to the suction line

19. Superheat is found in an air conditioning system in the...
An acid-core suction line drier
Evaporator and compressor
A sensing bulb improperly connected to the suction line
High superheat and low discharge pressure

20. 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
Technician B
Contains a solenoid coil and one or more sets of contacts
Rise more than normal
A defective circuit breaker

21. A technician arrives on the job and the customer complains that there is no cooling on his rooftop unit. Troubleshooting the system - the technician finds that the compressor is faulty. He notices that there is another faulty compressor laying next t
A bad thermostat
Broken rings+broken valves+seized bearings
Technician B
Always have some liquid present in the bulb and diaphragm

22. 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
A bad thermostat
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Whenever necessary
An uninsulated suction line and a restricted metering device

23. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
Low voltage and a faulty start relay
A missing air filter+improper rotation of the indoor blower+blower too small
A start capacitor and a solid-state relay

24. The temperature range of the suction line from an air conditioning system should be...
The oil pump pressure and the crankcase pressure
A plugged filter drier
50-65
An acid-core suction line drier

25. A hard-start kit for an air conditioning system...
Both technicians are correct
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Increases starting torque
Low superheat

26. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Evaporator and compressor
Low discharge pressure - high suction pressure - and low amp draw
Current in the compressor circuit
High suction pressure and low superheat

27. 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
Technician B
A defective circuit breaker
An undercharged system+insufficient airflow over the evaporator coil
A low refrigerant charge

28. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
('Y' and 'C') and ('G' and 'C')
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Bad compressor valve
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

29. 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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30. A system that uses a thermal electric expansion valve...
An uninsulated TXV sensing bulb
An undercharge and low ambient conditions
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Short cycling and insufficient dehumidification

31. A system that uses a thermal electric expansion valve...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Current in the compressor circuit
Flooding the condenser - cycling condenser fans - and dampering condenser air

32. 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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33. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
The low-side pressure will decrease and the evaporator coil will be partially frosted
('Y' and 'C') and ('G' and 'C')
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

34. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
Clean the condenser coil
An undercharge and low ambient conditions

35. 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
Technician B
A defective circuit breaker
An undercharged system+insufficient airflow over the evaporator coil

36. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Run with high head and high suction pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
High suction pressure and low superheat
A restricted metering device

37. Air filters should be replaced...
An uninsulated suction line and a restricted metering device
Whenever necessary
50-65
50-65

38. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
The superheat will increase and the low-side pressure will decrease
Technician B
The sensing bulb at a lower temperature than the valve body
Lack of airflow

39. Why is it unsafe to operate an air conditioning system with a low charge...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The superheat increases and the subcooling decreases
Condenser fans operating during a low ambient condition and a low suction pressure
The superheat increases and the subcooling decreases

40. A hard-start kit consists of...
A start capacitor and a solid-state relay
An acid-core suction line drier
It would cause the low-side pressure to decrease
A missing air filter+improper rotation of the indoor blower+blower too small

41. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
It would cause the low-side pressure to decrease
An undercharge and low ambient conditions
The low-side pressure will decrease and the evaporator coil will be partially frosted
An increase in suction pressure and an increase in discharge pressure

42. 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
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A defective circuit breaker
The low-side pressure will decrease and the evaporator coil will be partially frosted

43. What component is most often the cause of a start capacitor failure...
An acid-core suction line drier
Run with high head and high suction pressure
Technician A
A start relay

44. A commercial customer calls on a 90
Technician B
The system has been overcharged+The system has air trapped in the condenser
Broken rings+broken valves+seized bearings
The external equalizer could be plugged

45. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A start capacitor and a solid-state relay
An uninsulated suction line and a restricted metering device
('Y' and 'C') and ('G' and 'C')
Run with high head and high suction pressure

46. A compressor having tight bearings would cause the current value to...
Rise more than normal
'G' to 'C'
A sensing bulb improperly connected to the suction line
Technician B

47. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Technician B
An undercharged system+insufficient airflow over the evaporator coil
The superheat will increase and the low-side pressure will decrease
Technician A is correct

48. 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
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
20 to 30
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

49. Why is it unsafe to operate an air conditioning system with a low charge...
Technician B
'G' to 'C'
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

50. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Condenser fans operating during a low ambient condition and a low suction pressure
A sensing bulb improperly connected to the suction line
Partially frosted evaporator and high superheat
An undercharge and low ambient conditions