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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. Insufficient airflow can be caused by...
Both technicians are correct
An increase of air leakage from ductwork
A sensing bulb improperly connected to the suction line
Technician B

2. Insufficient airflow can be caused by...
3 psig
A bad thermostat
An overcharged system
An increase of air leakage from ductwork

3. What are the symptoms of an air conditioning system that has a low charge...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Increases starting torque
Always have some liquid present in the bulb and diaphragm
A defective circuit breaker

4. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
It is used to control refrigerant pressure in the compressor crankcase
Technician B
Technician B
110-120

5. 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
Both technicians are incorrect
Run with high head and high suction pressure
Clean the condenser coil
The system has been overcharged+The system has air trapped in the condenser

6. 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
An uninsulated suction line and a restricted metering device
Increases starting torque
A missing air filter+improper rotation of the indoor blower+blower too small

7. 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
The external equalizer could be plugged
Both technicians are correct
An undercharge and low ambient conditions
Clean the condenser coil

8. Air filters should be replaced...
50-65
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
High suction pressure and low superheat
Whenever necessary

9. What component is most often the cause of a start capacitor failure...
A start relay
('Y' and 'C') and ('G' and 'C')
The system has been overcharged+The system has air trapped in the condenser
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

10. 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
Evaporator and compressor
Technician A is correct
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B

11. What causes the automatic expansion valve to close...
An increase in low-side pressure
Low discharge pressure - high suction pressure - and low amp draw
An increase in suction pressure and an increase in discharge pressure
The superheat increases and the subcooling decreases

12. 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
High suction pressure and low superheat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are correct
Technician A is correct

13. A hard-start kit for an air conditioning system...
Rise more than normal
Both technicians are correct
Increases starting torque
A dirty condenser - recirculation of condenser air - and a defective condenser fan

14. Why is it unsafe to operate an air conditioning system with a low charge...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
Technician B

15. 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
Current in the compressor circuit
The low-side pressure will decrease and the evaporator coil will be partially frosted
A bad thermostat
Both technicians are correct

16. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
'G' to 'C'
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

17. The best description of a relay would be...
An increase in suction pressure and an increase in discharge pressure
The discharge pressure increases and the amperage increases
It keeps a constant superheat in the evaporator
Contains a solenoid coil and one or more sets of contacts

18. Which of the following is a common cause of an excessively low superheat on a TXV system...
Condenser fans operating during a low ambient condition and a low suction pressure
Contains a solenoid coil and one or more sets of contacts
A bad thermostat
A sensing bulb improperly connected to the suction line

19. Which of the following can cause low superheat in a TXV system...
Technician B
A blown fuse
The external equalizer could be plugged
An uninsulated TXV sensing bulb

20. 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
Whenever necessary
Broken rings+broken valves+seized bearings
Lack of airflow
Technician B

21. 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...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Condenser fans operating during a low ambient condition and a low suction pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Both technicians are incorrect

22. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An increase in suction pressure and an increase in discharge pressure
'G' to 'C'
Condenser fans operating during a low ambient condition and a low suction pressure

23. 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
High superheat and low discharge pressure
The internal overload is opened
A bad thermostat

24. What is the purpose of an EPR valve...
20 to 30
Bad compressor valve
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The discharge pressure increases and the amperage increases

25. 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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26. Air filters should be replaced...
Partially frosted evaporator and high superheat
Whenever necessary
A vacuum test+oil traces around fittings+soap bubble solution
A dirty condenser - recirculation of condenser air - and a defective condenser fan

27. A restricted air filter in an air conditioning system can be identified by...
Low superheat
A vacuum test+oil traces around fittings+soap bubble solution
3 psig
High superheat and low discharge pressure

28. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Condenser fans operating during a low ambient condition and a low suction pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
'G' to 'C'
Run with high head and high suction pressure

29. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician A
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are incorrect
The superheat increases and the subcooling decreases

30. The temperature range of the suction line from an air conditioning system should be...
3 psig
50-65
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

31. What are the symptoms of a TXV air conditioning system if it has lost its charge...
50-65
Technician B
The superheat will increase and the low-side pressure will decrease
An undercharge and low ambient conditions

32. 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
Both technicians are incorrect
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An increase in suction pressure and an increase in discharge pressure
An overcharged system

33. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are incorrect
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Both technicians are correct

34. 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
The external equalizer could be plugged
Low voltage and a faulty start relay
Technician B
Technician B

35. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Always have some liquid present in the bulb and diaphragm
'G' to 'C'
Technician B
3 psig

36. A hard-start kit consists of...
An uninsulated TXV sensing bulb
A start capacitor and a solid-state relay
'G' to 'C'
Short cycling and insufficient dehumidification

37. What are common methods that are used for leak-testing a system...
A low refrigerant charge
An uninsulated suction line and a restricted metering device
A vacuum test+oil traces around fittings+soap bubble solution
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

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
Technician B
A bad thermostat
It keeps a constant superheat in the evaporator
The superheat increases and the subcooling decreases

39. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
The low-side pressure will decrease and the evaporator coil will be partially frosted
The low-side pressure will decrease and the evaporator coil will be partially frosted
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

40. Which of the following can cause excessive subcooling...
A low refrigerant charge
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An overcharged system
Technician B

41. What are two problems that can cause an air conditioning system to have an excessively high superheat...
20 to 30
Technician B
An uninsulated suction line and a restricted metering device
Technician B

42. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Technician B
A plugged filter drier
Rise more than normal
A start relay

43. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
The low-side pressure will decrease and the evaporator coil will be partially frosted
Increases starting torque
An undercharged system+insufficient airflow over the evaporator coil

44. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
50-65
An uninsulated suction line and a restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An undercharge and low ambient conditions

45. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
50-65
An open internal overload protector

46. 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
An overcharged system
Lack of airflow
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Both technicians are incorrect

47. Which of the following is a possible cause for a compressor to overheat...
An undercharged system+insufficient airflow over the evaporator coil
A missing air filter+improper rotation of the indoor blower+blower too small
A low refrigerant charge
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

48. A restricted air filter in an air conditioning system can be identified by...
The sight glass is full of liquid+the sight glass is full of gas
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Low superheat
A bad thermostat

49. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
High superheat and low discharge pressure
A start relay
It would cause the low-side pressure to decrease

50. 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
Both technicians are incorrect
The low-side pressure will decrease and the evaporator coil will be partially frosted
Whenever necessary