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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 an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
A start relay
Lack of airflow
Clean the condenser coil

2. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Flooding the condenser - cycling condenser fans - and dampering condenser air
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Whenever necessary

3. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Low superheat
Technician B
Technician B

4. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
A missing air filter+improper rotation of the indoor blower+blower too small
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
3 psig

5. 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 thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
It keeps a constant superheat in the evaporator
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

6. What is the common cause of a compressor burnout...
Always have some liquid present in the bulb and diaphragm
Bad compressor valve
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Both technicians are incorrect

7. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The low-side pressure will decrease and the evaporator coil will be partially frosted
110-120
Technician B
A bad thermostat

8. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
An undercharged system+insufficient airflow over the evaporator coil
Run with high head and high suction pressure
The sight glass is full of liquid+the sight glass is full of gas
High suction pressure and low superheat

9. What is the common cause of a compressor burnout...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The superheat increases and the subcooling decreases
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The sight glass is full of liquid+the sight glass is full of gas

10. What is the purpose of an EPR valve...
An acid-core suction line drier
Contains a solenoid coil and one or more sets of contacts
It is used to control refrigerant pressure in the compressor crankcase
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

11. What component is most often the cause of a start capacitor failure...
A start relay
Low voltage and a faulty start relay
Always have some liquid present in the bulb and diaphragm
Run with high head and high suction pressure

12. The temperature range of the suction line from an air conditioning system should be...
An undercharged system+insufficient airflow over the evaporator coil
50-65
The superheat increases and the subcooling decreases
Technician B

13. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Run with high head and high suction pressure
A sensing bulb improperly connected to the suction line
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

14. A hard-start kit consists of...
Condenser fans operating during a low ambient condition and a low suction pressure
A low refrigerant charge
A start capacitor and a solid-state relay
An overcharged system

15. A customer calls with an insufficient cooling complaint on a 90
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A blown fuse
Technician B
The discharge pressure increases and the amperage increases

16. 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
The oil pump pressure and the crankcase pressure
An undercharged system+insufficient airflow over the evaporator coil
Both technicians are incorrect
The oil pump pressure and the crankcase pressure

17. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Whenever necessary
A restricted metering device
A start relay

18. 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
An increase in low-side pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The external equalizer could be plugged
A bad thermostat

19. What type of problems can be caused by an oversized air conditioning system...
A start relay
Short cycling and insufficient dehumidification
'G' to 'C'
Technician B

20. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
A plugged filter drier
An overcharged system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

21. Superheat is found in an air conditioning system in the...
A blown fuse
20 to 30
Evaporator and compressor
Contains a solenoid coil and one or more sets of contacts

22. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Low discharge pressure - high suction pressure - and low amp draw
Flooding the condenser - cycling condenser fans - and dampering condenser air
High superheat and low discharge pressure
An increase in suction pressure and an increase in discharge pressure

23. What causes the automatic expansion valve to close...
The system has been overcharged+The system has air trapped in the condenser
An increase in low-side pressure
A low refrigerant charge
It keeps a constant superheat in the evaporator

24. 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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25. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
The external equalizer could be plugged
The sensing bulb at a lower temperature than the valve body
Lack of airflow
A bad thermostat

26. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
Technician B

27. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Always have some liquid present in the bulb and diaphragm
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician A
A plugged filter drier

28. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A sensing bulb improperly connected to the suction line
Run with high head and high suction pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

29. 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
An uninsulated TXV sensing bulb
A blown fuse
The sensing bulb at a lower temperature than the valve body
Technician A is correct

30. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
It is used to control refrigerant pressure in the compressor crankcase
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
110-120

31. 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...
It keeps a constant superheat in the evaporator
Short cycling and insufficient dehumidification
Low voltage and a faulty start relay
('Y' and 'C') and ('G' and 'C')

32. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
50-65

33. 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...
20 to 30
Always have some liquid present in the bulb and diaphragm
The internal overload is opened
Technician B

34. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
It would cause the low-side pressure to decrease
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The superheat increases and the subcooling decreases

35. 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...
An acid-core suction line drier
A blown fuse
The oil pump pressure and the crankcase pressure
A start relay

36. 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...
Clean the condenser coil
A missing air filter+improper rotation of the indoor blower+blower too small
Low voltage and a faulty start relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

37. What are the symptoms of an air conditioning system that has a low charge...
The oil pump pressure and the crankcase pressure
Condenser fans operating during a low ambient condition and a low suction pressure
It would cause the low-side pressure to decrease
The low-side pressure will decrease and the evaporator coil will be partially frosted

38. A liquid-charged TXV bulb will...
The internal overload is opened
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Always have some liquid present in the bulb and diaphragm
An acid-core suction line drier

39. 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
A sensing bulb improperly connected to the suction line
A vacuum test+oil traces around fittings+soap bubble solution
Technician B
Partially frosted evaporator and high superheat

40. A system that is operating with a clear sight glass shows...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Both technicians are correct
The internal overload is opened
The sight glass is full of liquid+the sight glass is full of gas

41. Which of the following is a common cause of an excessively low superheat on a TXV system...
The system has been overcharged+The system has air trapped in the condenser
A sensing bulb improperly connected to the suction line
The superheat will increase and the low-side pressure will decrease
Technician B

42. 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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43. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Evaporator and compressor
It would cause the low-side pressure to decrease
A missing air filter+improper rotation of the indoor blower+blower too small
An undercharge and low ambient conditions

44. The temperature range of the suction line from an air conditioning system should be...
Run with high head and high suction pressure
Low superheat
50-65
Both technicians are incorrect

45. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Bad compressor valve
An increase of air leakage from ductwork

46. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An overcharged system
110-120
The external equalizer could be plugged

47. 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
A missing air filter+improper rotation of the indoor blower+blower too small
A low refrigerant charge
A vacuum test+oil traces around fittings+soap bubble solution

48. What is the purpose of a CPR valve...
An uninsulated suction line and a restricted metering device
The sight glass is full of liquid+the sight glass is full of gas
It is used to control refrigerant pressure in the compressor crankcase
'G' to 'C'

49. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
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
The superheat will increase and the low-side pressure will decrease

50. Which of the following can cause excessive subcooling...
An overcharged system
Technician B
An acid-core suction line drier
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure