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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. Which of the following will cause excessive discharge pressures on an air conditioning system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An increase in suction pressure and an increase in discharge pressure
Technician A is correct
The system has been overcharged+The system has air trapped in the condenser

2. 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 open internal overload protector
Both technicians are correct
Technician B
Current in the compressor circuit

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 blown fuse
Lack of airflow
Low discharge pressure - high suction pressure - and low amp draw
Both technicians are incorrect

4. 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
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The oil pump pressure and the crankcase pressure

5. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
A missing air filter+improper rotation of the indoor blower+blower too small
The superheat will increase and the low-side pressure will decrease

6. A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that the system is using are-22 with the high-side pressure at 290 psig and the low-side pressure at 85 psig. The ambient temperature is 85
20 to 30
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An acid-core suction line drier
Technician A

7. What type of problems can be caused by an oversized air conditioning system...
Increases starting torque
Short cycling and insufficient dehumidification
Increases starting torque
20 to 30

8. Technician A says ' When charging a system using the superheat method - adding refrigerant to the system will increase the superheat.' Technician B says 'When charging a system using the superheat method - adding refrigerant will decrease the superhe
Whenever necessary
The internal overload is opened
Technician B
An increase in low-side pressure

9. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
The oil pump pressure and the crankcase pressure
The internal overload is opened
Short cycling and insufficient dehumidification

10. What is the purpose of a CPR valve...
Technician B
Low voltage and a faulty start relay
It is used to control refrigerant pressure in the compressor crankcase
Current in the compressor circuit

11. 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
The sensing bulb at a lower temperature than the valve body
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Current in the compressor circuit

12. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Rise more than normal
An overcharged system
Lack of airflow
The sight glass is full of liquid+the sight glass is full of gas

13. What are common methods that are used for leak-testing a system...
Short cycling and insufficient dehumidification
It keeps a constant superheat in the evaporator
A vacuum test+oil traces around fittings+soap bubble solution
An undercharge and low ambient conditions

14. What is the purpose of an EPR valve...
Technician B
An overcharged system
'G' to 'C'
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

15. Why is it unsafe to operate an air conditioning system with a low charge...
Lack of airflow
Technician A is correct
Increases starting torque
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

16. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
High suction pressure and low superheat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Run with high head and high suction pressure

17. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The superheat will increase and the low-side pressure will decrease
The discharge pressure increases and the amperage increases
Run with high head and high suction pressure
An overcharged system

18. 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...
Broken rings+broken valves+seized bearings
('Y' and 'C') and ('G' and 'C')
Rise more than normal
Low voltage and a faulty start relay

19. What are two problems that can cause an air conditioning system to have an excessively high superheat...
The superheat increases and the subcooling decreases
The sight glass is full of liquid+the sight glass is full of gas
An uninsulated suction line and a restricted metering device
A restricted metering device

20. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A sensing bulb improperly connected to the suction line
A low refrigerant charge
Rise more than normal

21. The best description of a relay would be...
The sensing bulb at a lower temperature than the valve body
Technician A is correct
Contains a solenoid coil and one or more sets of contacts
Low superheat

22. 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
The oil pump pressure and the crankcase pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A plugged filter drier

23. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Low discharge pressure - high suction pressure - and low amp draw

24. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Always have some liquid present in the bulb and diaphragm
Both technicians are correct
The sensing bulb at a lower temperature than the valve body
The discharge pressure increases and the amperage increases

25. 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
Both technicians are incorrect
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
Increases starting torque

26. 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 defective circuit breaker
Both technicians are incorrect
Low discharge pressure - high suction pressure - and low amp draw

27. A hard-start kit for an air conditioning system...
An undercharged system+insufficient airflow over the evaporator coil
Condenser fans operating during a low ambient condition and a low suction pressure
Increases starting torque
A low refrigerant charge

28. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
The oil pump pressure and the crankcase pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
('Y' and 'C') and ('G' and 'C')
It would cause the low-side pressure to decrease

29. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
50-65
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An overcharged system

30. 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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31. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
Technician B
Rise more than normal
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

32. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A defective circuit breaker
Both technicians are incorrect
An overcharged system
An increase in suction pressure and an increase in discharge pressure

33. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
An open internal overload protector
High superheat and low discharge pressure
A bad thermostat

34. What component is most often the cause of a start capacitor failure...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A start relay
Low voltage and a faulty start relay
Contains a solenoid coil and one or more sets of contacts

35. A hard-start kit for an air conditioning system...
A restricted metering device
An increase in low-side pressure
A sensing bulb improperly connected to the suction line
Increases starting torque

36. 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
Condenser fans operating during a low ambient condition and a low suction pressure
The discharge pressure increases and the amperage increases
An increase in suction pressure and an increase in discharge pressure

37. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
It keeps a constant superheat in the evaporator
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B

38. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
A blown fuse
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The low-side pressure will decrease and the evaporator coil will be partially frosted

39. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
The oil pump pressure and the crankcase pressure
The system has been overcharged+The system has air trapped in the condenser
It would cause the low-side pressure to decrease
An undercharge and low ambient conditions

40. 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
High suction pressure and low superheat
A defective circuit breaker
Condenser fans operating during a low ambient condition and a low suction pressure

41. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An increase of air leakage from ductwork
Technician B
An overcharged system
Technician B

42. What causes the automatic expansion valve to close...
Technician B
An increase in low-side pressure
Technician B
Lack of airflow

43. 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
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in low-side pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

44. What is the purpose of an EPR valve...
Technician A
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Low voltage and a faulty start relay
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

45. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Technician A is correct
Run with high head and high suction pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

46. Which of the following is a common cause of an excessively low superheat on a TXV system...
Run with high head and high suction pressure
A restricted metering device
An undercharge and low ambient conditions
A sensing bulb improperly connected to the suction line

47. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The discharge pressure increases and the amperage increases
A dirty condenser - recirculation of condenser air - and a defective condenser fan
110-120
Partially frosted evaporator and high superheat

48. Air filters should be replaced...
Always have some liquid present in the bulb and diaphragm
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
3 psig
Whenever necessary

49. 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'
Run with high head and high suction pressure
An acid-core suction line drier
An open internal overload protector

50. 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
An uninsulated suction line and a restricted metering device
Rise more than normal
It keeps a constant superheat in the evaporator