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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 three things can prevent an air conditioning system from releasing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The external equalizer could be plugged
A defective circuit breaker
Technician B

2. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An uninsulated TXV sensing bulb
An acid-core suction line drier
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

3. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
110-120
A missing air filter+improper rotation of the indoor blower+blower too small

4. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Technician B
An undercharge and low ambient conditions
A low refrigerant charge
Run with high head and high suction pressure

5. 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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6. A liquid-charged TXV bulb will...
Low discharge pressure - high suction pressure - and low amp draw
Always have some liquid present in the bulb and diaphragm
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
('Y' and 'C') and ('G' and 'C')

7. 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...
The oil pump pressure and the crankcase pressure
High superheat and low discharge pressure
The superheat will increase and the low-side pressure will decrease
The low-side pressure will decrease and the evaporator coil will be partially frosted

8. A system that is operating with a clear sight glass shows...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The sight glass is full of liquid+the sight glass is full of gas
An acid-core suction line drier
Lack of airflow

9. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Technician B
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
Technician B

10. What are common methods that are used for leak-testing a system...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A vacuum test+oil traces around fittings+soap bubble solution
'G' to 'C'
Technician B

11. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Whenever necessary
Rise more than normal
An acid-core suction line drier
Technician B

12. 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
Low voltage and a faulty start relay
Low superheat
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

13. Which of the following is a common cause of an excessively low superheat on a TXV system...
Both technicians are correct
A sensing bulb improperly connected to the suction line
The sensing bulb at a lower temperature than the valve body
A restricted metering device

14. A commercial customer calls on a 90
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
110-120
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

15. A commercial customer calls on a 90
Technician B
A plugged filter drier
The system has been overcharged+The system has air trapped in the condenser
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

16. A system that is operating with a clear sight glass shows...
An increase of air leakage from ductwork
The sight glass is full of liquid+the sight glass is full of gas
A sensing bulb improperly connected to the suction line
An open internal overload protector

17. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
Lack of airflow
The internal overload is opened
Low superheat

18. What component is most often the cause of a start capacitor failure...
An open internal overload protector
A start relay
Increases starting torque
Low voltage and a faulty start relay

19. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A sensing bulb improperly connected to the suction line
Lack of airflow
Current in the compressor circuit
'G' to 'C'

20. What are two problems that can cause an air conditioning system to have an excessively high superheat...
'G' to 'C'
An uninsulated suction line and a restricted metering device
Clean the condenser coil
A missing air filter+improper rotation of the indoor blower+blower too small

21. A liquid-charged TXV bulb will...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Always have some liquid present in the bulb and diaphragm
A bad thermostat
Technician A is correct

22. 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
'G' to 'C'
An open internal overload protector
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Lack of airflow

23. Air filters should be replaced...
An undercharged system+insufficient airflow over the evaporator coil
A vacuum test+oil traces around fittings+soap bubble solution
The system has been overcharged+The system has air trapped in the condenser
Whenever necessary

24. A compressor having tight bearings would cause the current value to...
An overcharged system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Rise more than normal
It is used to control refrigerant pressure in the compressor crankcase

25. The internal overload of an air conditioning compressor senses winding temperature and...
An uninsulated suction line and a restricted metering device
Broken rings+broken valves+seized bearings
Current in the compressor circuit
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

26. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
Partially frosted evaporator and high superheat
3 psig
High suction pressure and low superheat

27. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
The internal overload is opened
An open internal overload protector
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

28. 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...
Contains a solenoid coil and one or more sets of contacts
Broken rings+broken valves+seized bearings
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

29. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Always have some liquid present in the bulb and diaphragm
Both technicians are incorrect
20 to 30
It is used to control refrigerant pressure in the compressor crankcase

30. What type of problems can be caused by an oversized air conditioning system...
An increase in low-side pressure
Short cycling and insufficient dehumidification
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Current in the compressor circuit

31. 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
Technician B
Always have some liquid present in the bulb and diaphragm
Clean the condenser coil
Evaporator and compressor

32. 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
Evaporator and compressor
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

33. What component is most often the cause of a start capacitor failure...
Rise more than normal
It would cause the low-side pressure to decrease
'G' to 'C'
A start relay

34. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
Broken rings+broken valves+seized bearings
Technician B
Technician A

35. A compressor having tight bearings would cause the current value to...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A plugged filter drier
Rise more than normal
A restricted metering device

36. The temperature range of the suction line from an air conditioning system should be...
50-65
20 to 30
It keeps a constant superheat in the evaporator
An overcharged system

37. 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 system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The internal overload is opened
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The external equalizer could be plugged

38. 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
Evaporator and compressor
'G' to 'C'
A bad thermostat
The oil pump pressure and the crankcase pressure

39. 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
Contains a solenoid coil and one or more sets of contacts
Technician B
The sensing bulb at a lower temperature than the valve body
Technician A is correct

40. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
'G' to 'C'
Low superheat
A missing air filter+improper rotation of the indoor blower+blower too small
The system has been overcharged+The system has air trapped in the condenser

41. Which of the following could be the cause for a system's discharge and suction pressure being low...
Flooding the condenser - cycling condenser fans - and dampering condenser air
High suction pressure and low superheat
It keeps a constant superheat in the evaporator
A restricted metering device

42. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The sensing bulb at a lower temperature than the valve body
An increase in suction pressure and an increase in discharge pressure
Low discharge pressure - high suction pressure - and low amp draw
Bad compressor valve

43. When using a vapor-charged TXV bulb - it is necessary to have...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The sensing bulb at a lower temperature than the valve body
A bad thermostat
The discharge pressure increases and the amperage increases

44. A restricted air filter in an air conditioning system can be identified by...
The external equalizer could be plugged
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
Low superheat

45. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Low voltage and a faulty start relay
Evaporator and compressor
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The external equalizer could be plugged

46. 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
Contains a solenoid coil and one or more sets of contacts
A plugged filter drier
A bad thermostat

47. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Clean the condenser coil
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B

48. 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 suction pressure and low superheat
Low voltage and a faulty start relay
The external equalizer could be plugged
The system has been overcharged+The system has air trapped in the condenser

49. Which of the following is a common cause of an excessively low superheat on a TXV system...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
'G' to 'C'
A sensing bulb improperly connected to the suction line
A plugged filter drier

50. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
50-65
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
3 psig