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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. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An open internal overload protector
The superheat increases and the subcooling decreases
Condenser fans operating during a low ambient condition and a low suction pressure
Lack of airflow

2. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Clean the condenser coil
Both technicians are correct
Whenever necessary
3 psig

3. Superheat is found in an air conditioning system in the...
The system has been overcharged+The system has air trapped in the condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Evaporator and compressor

4. 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
An overcharged system
A bad thermostat
Increases starting torque
The system has been overcharged+The system has air trapped in the condenser

5. 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
Technician B
Whenever necessary
3 psig
The external equalizer could be plugged

6. Which of the following can cause low superheat in a TXV system...
It keeps a constant superheat in the evaporator
An uninsulated TXV sensing bulb
A missing air filter+improper rotation of the indoor blower+blower too small
The low-side pressure will decrease and the evaporator coil will be partially frosted

7. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
Technician B
A restricted metering device
The superheat will increase and the low-side pressure will decrease

8. A technician receives an air conditioning service call stating that the system is operating but isn't cooling properly. When the technician arrives - she notices that the compressor has recently been changed and it is an are-22 system. She checks the
Technician B
Both technicians are correct
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An uninsulated TXV sensing bulb

9. A system that uses a thermal electric expansion valve...
Technician B
The sight glass is full of liquid+the sight glass is full of gas
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A plugged filter drier

10. Which of the following is a possible cause for a compressor to overheat...
Technician B
Whenever necessary
('Y' and 'C') and ('G' and 'C')
A low refrigerant charge

11. Why is it unsafe to operate an air conditioning system with a low charge...
Lack of airflow
'G' to 'C'
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B

12. Which of the following can cause excessive subcooling...
An overcharged system
The superheat will increase and the low-side pressure will decrease
Both technicians are incorrect
An increase in low-side pressure

13. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Bad compressor valve
110-120
Partially frosted evaporator and high superheat

14. 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
It keeps a constant superheat in the evaporator
An uninsulated suction line and a restricted metering device
Technician B

15. A customer calls with an insufficient cooling complaint on a 90
'G' to 'C'
A defective circuit breaker
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B

16. A hard-start kit for an air conditioning system...
Increases starting torque
'G' to 'C'
Technician B
Technician A is correct

17. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
The low-side pressure will decrease and the evaporator coil will be partially frosted
50-65
An overcharged system
High suction pressure and low superheat

18. 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
50-65
Low voltage and a faulty start relay
It would cause the low-side pressure to decrease
Technician B

19. Air filters should be replaced...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An undercharge and low ambient conditions
It is used to control refrigerant pressure in the compressor crankcase
Whenever necessary

20. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Technician B
The discharge pressure increases and the amperage increases
Rise more than normal
High superheat and low discharge pressure

21. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Short cycling and insufficient dehumidification
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
High suction pressure and low superheat
An overcharged system

22. A restricted air filter in an air conditioning system can be identified by...
An overcharged system
Low superheat
A plugged filter drier
20 to 30

23. Which of the following will cause excessive discharge pressures on an air conditioning system...
Broken rings+broken valves+seized bearings
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Condenser fans operating during a low ambient condition and a low suction pressure
The superheat will increase and the low-side pressure will decrease

24. What is the purpose of the TXV...
Flooding the condenser - cycling condenser fans - and dampering condenser air
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A start relay
It keeps a constant superheat in the evaporator

25. 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
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An uninsulated TXV sensing bulb
A bad thermostat

26. Which of the following can cause excessive subcooling...
An overcharged system
A low refrigerant charge
A restricted metering device
A vacuum test+oil traces around fittings+soap bubble solution

27. What are the operating pressures of an oil pressure safety switch...
Current in the compressor circuit
The superheat will increase and the low-side pressure will decrease
Both technicians are incorrect
The oil pump pressure and the crankcase pressure

28. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Low superheat
Low voltage and a faulty start relay
20 to 30

29. A compressor having tight bearings would cause the current value to...
The internal overload is opened
Rise more than normal
A low refrigerant charge
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

30. A system that uses a thermal electric expansion valve...
The sight glass is full of liquid+the sight glass is full of gas
Technician A is correct
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

31. 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...
An uninsulated TXV sensing bulb
Condenser fans operating during a low ambient condition and a low suction pressure
A start relay
A missing air filter+improper rotation of the indoor blower+blower too small

32. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated suction line and a restricted metering device
It would cause the low-side pressure to decrease
Partially frosted evaporator and high superheat
Technician A is correct

33. 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
It would cause the low-side pressure to decrease
Broken rings+broken valves+seized bearings
A vacuum test+oil traces around fittings+soap bubble solution

34. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
20 to 30
Low superheat
The sensing bulb at a lower temperature than the valve body

35. The internal overload of an air conditioning compressor senses winding temperature and...
An increase in low-side pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Current in the compressor circuit
A missing air filter+improper rotation of the indoor blower+blower too small

36. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A start capacitor and a solid-state relay
The superheat increases and the subcooling decreases
Clean the condenser coil
Both technicians are correct

37. 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...
Rise more than normal
Condenser fans operating during a low ambient condition and a low suction pressure
3 psig
A missing air filter+improper rotation of the indoor blower+blower too small

38. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
A defective circuit breaker
Partially frosted evaporator and high superheat
A restricted metering device

39. Which of the following is a common cause of an excessively low superheat on a TXV system...
A plugged filter drier
A sensing bulb improperly connected to the suction line
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
High suction pressure and low superheat

40. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Always have some liquid present in the bulb and diaphragm
50-65
A dirty condenser - recirculation of condenser air - and a defective condenser fan
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

41. The best description of a relay would be...
The discharge pressure increases and the amperage increases
Contains a solenoid coil and one or more sets of contacts
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
High suction pressure and low superheat

42. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Both technicians are incorrect
Technician B
An uninsulated suction line and a restricted metering device
An open internal overload protector

43. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Run with high head and high suction pressure
A missing air filter+improper rotation of the indoor blower+blower too small
Whenever necessary

44. What is the purpose of a CPR valve...
A blown fuse
Evaporator and compressor
An open internal overload protector
It is used to control refrigerant pressure in the compressor crankcase

45. The temperature range of the suction line from an air conditioning system should be...
An increase of air leakage from ductwork
50-65
A defective circuit breaker
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

46. A split-system air conditioner that uses a piston-type metering device is to be charged with are-22. Technician A says that the outdoor dry-bulb temperature is needed to determine the proper superheat. Technician B says that the indoor wet-bulb tempe
Clean the condenser coil
Technician B
Both technicians are correct
The sight glass is full of liquid+the sight glass is full of gas

47. 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
An open internal overload protector
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Both technicians are incorrect
'G' to 'C'

48. What are three methods for controlling a system's high-side pressure during low ambient conditions...
An overcharged system
Flooding the condenser - cycling condenser fans - and dampering condenser air
The system has been overcharged+The system has air trapped in the condenser
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

49. A compressor having tight bearings would cause the current value to...
An uninsulated suction line and a restricted metering device
Lack of airflow
Both technicians are incorrect
Rise more than normal

50. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A restricted metering device
High superheat and low discharge pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil