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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 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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2. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Both technicians are correct
An uninsulated suction line and a restricted metering device
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Whenever necessary

3. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An overcharged system
Bad compressor valve

4. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
Lack of airflow
Bad compressor valve
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

5. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Whenever necessary
Technician B
The superheat will increase and the low-side pressure will decrease
An increase in suction pressure and an increase in discharge pressure

6. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Lack of airflow
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in suction pressure and an increase in discharge pressure

7. 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
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A defective circuit breaker
('Y' and 'C') and ('G' and 'C')

8. Which of the following can cause excessive subcooling...
A plugged filter drier
An overcharged system
('Y' and 'C') and ('G' and 'C')
Lack of airflow

9. The best description of a relay would be...
An increase of air leakage from ductwork
Broken rings+broken valves+seized bearings
Whenever necessary
Contains a solenoid coil and one or more sets of contacts

10. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
Low discharge pressure - high suction pressure - and low amp draw
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An uninsulated TXV sensing bulb

11. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An increase in low-side pressure
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
110-120

12. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
20 to 30
An overcharged system

13. What are the symptoms of an air conditioning system that has a low charge...
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
Partially frosted evaporator and high superheat
A sensing bulb improperly connected to the suction line

14. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
Technician A is correct
The discharge pressure increases and the amperage increases
Lack of airflow

15. 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
Increases starting torque
Contains a solenoid coil and one or more sets of contacts
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

16. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
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
An undercharge and low ambient conditions

17. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An undercharge and low ambient conditions
Technician B
Contains a solenoid coil and one or more sets of contacts

18. 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
Partially frosted evaporator and high superheat
It would cause the low-side pressure to decrease
Low superheat
Both technicians are incorrect

19. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Technician B
An increase in suction pressure and an increase in discharge pressure
An overcharged system
An increase of air leakage from ductwork

20. Which of the following is a possible cause for a compressor to overheat...
An uninsulated suction line and a restricted metering device
Both technicians are correct
A low refrigerant charge
A plugged filter drier

21. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

22. What component is most often the cause of a start capacitor failure...
The system has been overcharged+The system has air trapped in the condenser
A start relay
Evaporator and compressor
Both technicians are correct

23. Insufficient airflow can be caused by...
The superheat increases and the subcooling decreases
An increase of air leakage from ductwork
It is used to control refrigerant pressure in the compressor crankcase
Technician B

24. 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
The sight glass is full of liquid+the sight glass is full of gas
A plugged filter drier
A low refrigerant charge
A defective circuit breaker

25. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A blown fuse
The system has been overcharged+The system has air trapped in the condenser

26. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Flooding the condenser - cycling condenser fans - and dampering condenser air
A sensing bulb improperly connected to the suction line

27. 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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28. 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
Both technicians are correct
An acid-core suction line drier
Increases starting torque

29. 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 vacuum test+oil traces around fittings+soap bubble solution
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

30. A system that is operating with a clear sight glass shows...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The sight glass is full of liquid+the sight glass is full of gas
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A low refrigerant charge

31. What problem or problems can cause low discharge and suction pressure...
('Y' and 'C') and ('G' and 'C')
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Always have some liquid present in the bulb and diaphragm
An undercharged system+insufficient airflow over the evaporator coil

32. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
The low-side pressure will decrease and the evaporator coil will be partially frosted
An increase in low-side pressure
A missing air filter+improper rotation of the indoor blower+blower too small

33. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A plugged filter drier
Bad compressor valve
Technician B
Whenever necessary

34. Which of the following could be the cause for a system's discharge and suction pressure being low...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A restricted metering device
An overcharged system
Lack of airflow

35. Which of the following will cause excessive discharge pressures on an air conditioning system...
Increases starting torque
Technician B
A start capacitor and a solid-state relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

36. When using a vapor-charged TXV bulb - it is necessary to have...
Short cycling and insufficient dehumidification
Both technicians are incorrect
The sensing bulb at a lower temperature than the valve body
A dirty condenser - recirculation of condenser air - and a defective condenser fan

37. 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
Both technicians are correct
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Broken rings+broken valves+seized bearings

38. What is the common cause of a compressor burnout...
Both technicians are incorrect
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
'G' to 'C'
Technician A

39. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
('Y' and 'C') and ('G' and 'C')
It would cause the low-side pressure to decrease
High suction pressure and low superheat
The system has been overcharged+The system has air trapped in the condenser

40. 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...
Lack of airflow
Both technicians are incorrect
A defective circuit breaker
The internal overload is opened

41. Which of the following is a common cause of an excessively low superheat on a TXV system...
A missing air filter+improper rotation of the indoor blower+blower too small
Partially frosted evaporator and high superheat
A sensing bulb improperly connected to the suction line
Whenever necessary

42. 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
A vacuum test+oil traces around fittings+soap bubble solution
The discharge pressure increases and the amperage increases
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Clean the condenser coil

43. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A plugged filter drier
Whenever necessary
A missing air filter+improper rotation of the indoor blower+blower too small

44. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
An increase in low-side pressure
A vacuum test+oil traces around fittings+soap bubble solution
The system has been overcharged+The system has air trapped in the condenser

45. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Both technicians are incorrect
An uninsulated suction line and a restricted metering device
Bad compressor valve
20 to 30

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 uninsulated TXV sensing bulb
Contains a solenoid coil and one or more sets of contacts
Both technicians are incorrect
An undercharge and low ambient conditions

47. A commercial customer calls on a 90
An overcharged system
A restricted metering device
The system has been overcharged+The system has air trapped in the condenser
Both technicians are incorrect

48. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A bad thermostat
It is used to control refrigerant pressure in the compressor crankcase
The superheat increases and the subcooling decreases
The discharge pressure increases and the amperage increases

49. 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
110-120
An overcharged system
It keeps a constant superheat in the evaporator
Technician A

50. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An increase of air leakage from ductwork
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
('Y' and 'C') and ('G' and 'C')
Evaporator and compressor