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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. A customer calls with an insufficient cooling complaint on a 90
The system has been overcharged+The system has air trapped in the condenser
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
An uninsulated suction line and a restricted metering device

2. 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
The oil pump pressure and the crankcase pressure
50-65
The oil pump pressure and the crankcase pressure

3. 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
It would cause the low-side pressure to decrease
Evaporator and compressor
Technician B
A restricted metering device

4. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An uninsulated TXV sensing bulb
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

5. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Both technicians are incorrect
Technician A is correct

6. Superheat is found in an air conditioning system in the...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Contains a solenoid coil and one or more sets of contacts
High superheat and low discharge pressure
Evaporator and compressor

7. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Condenser fans operating during a low ambient condition and a low suction pressure
Technician A is correct
Short cycling and insufficient dehumidification
High suction pressure and low superheat

8. A liquid-charged TXV bulb will...
Both technicians are incorrect
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Always have some liquid present in the bulb and diaphragm

9. 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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10. A system that uses a thermal electric expansion valve...
The low-side pressure will decrease and the evaporator coil will be partially frosted
The superheat increases and the subcooling decreases
It would cause the low-side pressure to decrease
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

11. 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
A plugged filter drier
An overcharged system
Bad compressor valve

12. Why is it unsafe to operate an air conditioning system with a low charge...
A plugged filter drier
An overcharged system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The external equalizer could be plugged

13. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Technician A is correct
The sensing bulb at a lower temperature than the valve body
20 to 30
50-65

14. A system that is operating with a clear sight glass shows...
Run with high head and high suction pressure
The sight glass is full of liquid+the sight glass is full of gas
An acid-core suction line drier
Contains a solenoid coil and one or more sets of contacts

15. Which of the following is a common cause of an excessively low superheat on a TXV system...
Technician B
A sensing bulb improperly connected to the suction line
Clean the condenser coil
An increase in low-side pressure

16. 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
Technician B
An overcharged system
Evaporator and compressor

17. 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 oil pump pressure and the crankcase pressure
An uninsulated suction line and a restricted metering device
Both technicians are correct
A blown fuse

18. What is the common cause of a compressor burnout...
Low superheat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An uninsulated TXV sensing bulb

19. Which of the following is a common cause of an excessively low superheat on a TXV system...
A sensing bulb improperly connected to the suction line
Clean the condenser coil
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Evaporator and compressor

20. Which of the following will cause excessive discharge pressures on an air conditioning system...
A sensing bulb improperly connected to the suction line
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
'G' to 'C'
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

21. What are two common symptoms of refrigerant leaks in an air conditioning system...
Lack of airflow
Partially frosted evaporator and high superheat
110-120
It keeps a constant superheat in the evaporator

22. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
A start capacitor and a solid-state relay
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Low discharge pressure - high suction pressure - and low amp draw

23. A system that uses a thermal electric expansion valve...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An uninsulated suction line and a restricted metering device

24. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
Broken rings+broken valves+seized bearings
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are incorrect

25. A liquid-charged TXV bulb will...
Technician B
Both technicians are incorrect
An undercharged system+insufficient airflow over the evaporator coil
Always have some liquid present in the bulb and diaphragm

26. What are two common symptoms of refrigerant leaks in an air conditioning system...
Technician B
Partially frosted evaporator and high superheat
The superheat increases and the subcooling decreases
A plugged filter drier

27. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A restricted metering device
Lack of airflow
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B

28. What problem or problems can cause low discharge and suction pressure...
The superheat increases and the subcooling decreases
An undercharged system+insufficient airflow over the evaporator coil
It would cause the low-side pressure to decrease
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

29. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An overcharged system
Clean the condenser coil
Condenser fans operating during a low ambient condition and a low suction pressure

30. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
High suction pressure and low superheat
It would cause the low-side pressure to decrease
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Contains a solenoid coil and one or more sets of contacts

31. 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
The low-side pressure will decrease and the evaporator coil will be partially frosted
A missing air filter+improper rotation of the indoor blower+blower too small
The external equalizer could be plugged

32. Insufficient airflow can be caused by...
The system has been overcharged+The system has air trapped in the condenser
Always have some liquid present in the bulb and diaphragm
An increase of air leakage from ductwork
The sight glass is full of liquid+the sight glass is full of gas

33. 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 overcharged system
Clean the condenser coil

34. 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
Technician A is correct
A defective circuit breaker
An uninsulated TXV sensing bulb
The external equalizer could be plugged

35. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
High superheat and low discharge pressure
Technician B
Technician A is correct
A missing air filter+improper rotation of the indoor blower+blower too small

36. 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 external equalizer could be plugged
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The system has been overcharged+The system has air trapped in the condenser

37. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
('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
A plugged filter drier

38. A restricted air filter in an air conditioning system can be identified by...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Low superheat
High suction pressure and low superheat

39. Which of the following can cause low superheat in a TXV system...
An overcharged system
An uninsulated TXV sensing bulb
Both technicians are incorrect
It would cause the low-side pressure to decrease

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
An undercharged system+insufficient airflow over the evaporator coil
50-65
('Y' and 'C') and ('G' and 'C')
Technician B

41. Which of the following can cause excessive subcooling...
It would cause the low-side pressure to decrease
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
An overcharged system

42. 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...
An acid-core suction line drier
Run with high head and high suction pressure
An undercharged system+insufficient airflow over the evaporator coil
The internal overload is opened

43. 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 B
Increases starting torque
Technician A is correct
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

44. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Condenser fans operating during a low ambient condition and a low suction pressure
Both technicians are incorrect
Flooding the condenser - cycling condenser fans - and dampering condenser air
A bad thermostat

45. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
An overcharged system
Always have some liquid present in the bulb and diaphragm
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

46. What causes the automatic expansion valve to close...
Technician B
An increase in low-side pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Dirty condenser - bent condenser fins - and air recirculating over the condenser

47. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
'G' to 'C'
Technician A
Contains a solenoid coil and one or more sets of contacts

48. What problem or problems can cause low discharge and suction pressure...
An increase of air leakage from ductwork
50-65
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An undercharged system+insufficient airflow over the evaporator coil

49. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
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
Technician B

50. What type of problems can be caused by an oversized air conditioning system...
An increase in low-side pressure
50-65
Low voltage and a faulty start relay
Short cycling and insufficient dehumidification