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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. 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
Short cycling and insufficient dehumidification
An overcharged system
Both technicians are correct
Technician B

2. Which of the following can cause excessive subcooling...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An overcharged system
An increase of air leakage from ductwork
Both technicians are incorrect

3. A restricted air filter in an air conditioning system can be identified by...
Technician B
Low superheat
A blown fuse
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

4. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An acid-core suction line drier

5. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Technician A is correct
The superheat will increase and the low-side pressure will decrease
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Bad compressor valve

6. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
It would cause the low-side pressure to decrease
The system has been overcharged+The system has air trapped in the condenser
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Partially frosted evaporator and high superheat

7. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
Always have some liquid present in the bulb and diaphragm
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted

8. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An undercharge and low ambient conditions
The sight glass is full of liquid+the sight glass is full of gas
A low refrigerant charge

9. 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
Always have some liquid present in the bulb and diaphragm
'G' to 'C'
Both technicians are incorrect

10. Air filters should be replaced...
An uninsulated TXV sensing bulb
Flooding the condenser - cycling condenser fans - and dampering condenser air
Short cycling and insufficient dehumidification
Whenever necessary

11. A technician arrives on the job and the customer complains that there is no cooling on his rooftop unit. Troubleshooting the system - the technician finds that the compressor is faulty. He notices that there is another faulty compressor laying next t
Run with high head and high suction pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
Broken rings+broken valves+seized bearings
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

12. 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
An increase of air leakage from ductwork
High suction pressure and low superheat
Technician A is correct

13. What component is most often the cause of a start capacitor failure...
A start relay
An acid-core suction line drier
Increases starting torque
'G' to 'C'

14. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
An undercharge and low ambient conditions
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A vacuum test+oil traces around fittings+soap bubble solution

15. 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
Technician B
Both technicians are correct
The sight glass is full of liquid+the sight glass is full of gas
Clean the condenser coil

16. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An acid-core suction line drier
Both technicians are incorrect
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

17. What is the purpose of a CPR valve...
('Y' and 'C') and ('G' and 'C')
It is used to control refrigerant pressure in the compressor crankcase
Low voltage and a faulty start relay
An overcharged system

18. Which of the following will cause excessive discharge pressures on an air conditioning system...
An uninsulated TXV sensing bulb
Evaporator and compressor
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

19. 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
Whenever necessary
Lack of airflow
Technician B
Technician A is correct

20. 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
Technician B
Run with high head and high suction pressure
It is used to control refrigerant pressure in the compressor crankcase
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

21. Why is it unsafe to operate an air conditioning system with a low charge...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

22. What are the symptoms of an air conditioning system that has a low charge...
A blown fuse
Current in the compressor circuit
The low-side pressure will decrease and the evaporator coil will be partially frosted
A sensing bulb improperly connected to the suction line

23. A technician arrives on the job and the customer complains that there is no cooling on his rooftop unit. Troubleshooting the system - the technician finds that the compressor is faulty. He notices that there is another faulty compressor laying next t
Technician B
An uninsulated suction line and a restricted metering device
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Broken rings+broken valves+seized bearings

24. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
An increase in low-side pressure
The external equalizer could be plugged
A defective circuit breaker

25. The best description of a relay would be...
Clean the condenser coil
Contains a solenoid coil and one or more sets of contacts
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Current in the compressor circuit

26. A restricted air filter in an air conditioning system can be identified by...
Technician B
The external equalizer could be plugged
Low superheat
An overcharged system

27. 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 low-side pressure will decrease and the evaporator coil will be partially frosted
An overcharged system
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

28. 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
Technician A
Technician B
An open internal overload protector
Technician B

29. What are common methods that are used for leak-testing a system...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A vacuum test+oil traces around fittings+soap bubble solution
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

30. 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 superheat increases and the subcooling decreases
An uninsulated TXV sensing bulb
The internal overload is opened
Low superheat

31. What are two common symptoms of refrigerant leaks in an air conditioning system...
The sight glass is full of liquid+the sight glass is full of gas
The internal overload is opened
Partially frosted evaporator and high superheat
The system has been overcharged+The system has air trapped in the condenser

32. 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
Clean the condenser coil
Short cycling and insufficient dehumidification
Whenever necessary
It keeps a constant superheat in the evaporator

33. What causes the automatic expansion valve to close...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Current in the compressor circuit
An increase in low-side pressure
Technician B

34. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
An increase of air leakage from ductwork
It is used to control refrigerant pressure in the compressor crankcase
110-120
Technician A

35. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
A blown fuse
Technician B
Lack of airflow

36. A system that uses a thermal electric expansion valve...
Low discharge pressure - high suction pressure - and low amp draw
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The discharge pressure increases and the amperage increases
A missing air filter+improper rotation of the indoor blower+blower too small

37. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Both technicians are incorrect
A blown fuse
The system has been overcharged+The system has air trapped in the condenser
110-120

38. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Technician A is correct
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A missing air filter+improper rotation of the indoor blower+blower too small

39. Which of the following will cause excessive discharge pressures on an air conditioning system...
The sensing bulb at a lower temperature than the valve body
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Rise more than normal

40. What causes the automatic expansion valve to close...
An increase in low-side pressure
It is used to control refrigerant pressure in the compressor crankcase
Short cycling and insufficient dehumidification
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

41. 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
Technician B
Lack of airflow
A dirty condenser - recirculation of condenser air - and a defective condenser fan

42. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
A start relay
Both technicians are correct
Flooding the condenser - cycling condenser fans - and dampering condenser air

43. A liquid-charged TXV bulb will...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Always have some liquid present in the bulb and diaphragm
High superheat and low discharge pressure
An acid-core suction line drier

44. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
The discharge pressure increases and the amperage increases
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It would cause the low-side pressure to decrease
Broken rings+broken valves+seized bearings

45. 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 undercharged system+insufficient airflow over the evaporator coil
An acid-core suction line drier
An uninsulated suction line and a restricted metering device
An overcharged system

46. A customer calls with an insufficient cooling complaint on a 90
Both technicians are incorrect
It is used to control refrigerant pressure in the compressor crankcase
Technician B
Lack of airflow

47. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
Technician A
Run with high head and high suction pressure
An acid-core suction line drier

48. 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
('Y' and 'C') and ('G' and 'C')
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Bad compressor valve

49. 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
Bad compressor valve
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Bad compressor valve

50. What component is most often the cause of a start capacitor failure...
High suction pressure and low superheat
An increase in suction pressure and an increase in discharge pressure
Condenser fans operating during a low ambient condition and a low suction pressure
A start relay