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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...
An uninsulated TXV sensing bulb
A missing air filter+improper rotation of the indoor blower+blower too small
A missing air filter+improper rotation of the indoor blower+blower too small
An increase of air leakage from ductwork

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
The internal overload is opened
Both technicians are incorrect
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

3. A compressor having tight bearings would cause the current value to...
Rise more than normal
A plugged filter drier
The internal overload is opened
Whenever necessary

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
Both technicians are correct
Technician A
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

5. Why is it unsafe to operate an air conditioning system with a low charge...
Increases starting torque
3 psig
An overcharged system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

6. 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
The low-side pressure will decrease and the evaporator coil will be partially frosted
Bad compressor valve
A vacuum test+oil traces around fittings+soap bubble solution
Both technicians are correct

7. What causes the automatic expansion valve to close...
Low superheat
An increase in low-side pressure
A low refrigerant charge
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

8. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Both technicians are correct

9. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
The superheat will increase and the low-side pressure will decrease
An undercharge and low ambient conditions
3 psig
Always have some liquid present in the bulb and diaphragm

10. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
An increase in suction pressure and an increase in discharge pressure
Low superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser

11. A hard-start kit for an air conditioning system...
An undercharged system+insufficient airflow over the evaporator coil
Increases starting torque
Technician A
The system has been overcharged+The system has air trapped in the condenser

12. What are the operating pressures of an oil pressure safety switch...
Technician B
Clean the condenser coil
Evaporator and compressor
The oil pump pressure and the crankcase pressure

13. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Short cycling and insufficient dehumidification
'G' to 'C'

14. What causes the automatic expansion valve to close...
An increase in low-side pressure
High superheat and low discharge pressure
Low superheat
The sensing bulb at a lower temperature than the valve body

15. 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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16. What are the operating pressures of an oil pressure safety switch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
High suction pressure and low superheat
A low refrigerant charge
The oil pump pressure and the crankcase pressure

17. What type of problems can be caused by an oversized air conditioning system...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The sensing bulb at a lower temperature than the valve body
Short cycling and insufficient dehumidification

18. A commercial customer calls on a 90
Both technicians are incorrect
A vacuum test+oil traces around fittings+soap bubble solution
Technician A is correct
The system has been overcharged+The system has air trapped in the condenser

19. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Low discharge pressure - high suction pressure - and low amp draw
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The superheat will increase and the low-side pressure will decrease
Flooding the condenser - cycling condenser fans - and dampering condenser air

20. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Both technicians are correct
Low voltage and a faulty start relay
20 to 30
The superheat increases and the subcooling decreases

21. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
Technician B
A start capacitor and a solid-state relay
Technician B

22. 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
Both technicians are correct
Technician A
Whenever necessary

23. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
An increase in low-side pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A low refrigerant charge

24. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
A vacuum test+oil traces around fittings+soap bubble solution
The discharge pressure increases and the amperage increases
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Condenser fans operating during a low ambient condition and a low suction pressure

25. A system that uses a thermal electric expansion valve...
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The internal overload is opened
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

26. Which of the following is a common cause of an excessively low superheat on a TXV system...
A defective circuit breaker
A sensing bulb improperly connected to the suction line
Technician B
'G' to 'C'

27. 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
A start capacitor and a solid-state relay
The oil pump pressure and the crankcase pressure
Both technicians are incorrect
Bad compressor valve

28. 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...
It keeps a constant superheat in the evaporator
The internal overload is opened
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The sight glass is full of liquid+the sight glass is full of gas

29. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
20 to 30
An acid-core suction line drier
A plugged filter drier
Short cycling and insufficient dehumidification

30. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
Short cycling and insufficient dehumidification
An increase of air leakage from ductwork
3 psig

31. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Both technicians are correct
('Y' and 'C') and ('G' and 'C')
A vacuum test+oil traces around fittings+soap bubble solution
Bad compressor valve

32. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
It keeps a constant superheat in the evaporator
An increase in suction pressure and an increase in discharge pressure
An open internal overload protector
An uninsulated suction line and a restricted metering device

33. 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
The sight glass is full of liquid+the sight glass is full of gas
The external equalizer could be plugged
Rise more than normal
Both technicians are incorrect

34. 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 A is correct
Short cycling and insufficient dehumidification
Whenever necessary
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

35. 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
The oil pump pressure and the crankcase pressure
Short cycling and insufficient dehumidification
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Broken rings+broken valves+seized bearings

36. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Evaporator and compressor
Condenser fans operating during a low ambient condition and a low suction pressure
The external equalizer could be plugged

37. If a rooftop air conditioning system does not have any means of low ambient protection - what will be two symptoms of the system when operating under a low ambient condition...
Low superheat
20 to 30
Technician B
High superheat and low discharge pressure

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
A bad thermostat
Broken rings+broken valves+seized bearings
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are incorrect

39. A hard-start kit consists of...
Technician A is correct
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An undercharged system+insufficient airflow over the evaporator coil
A start capacitor and a solid-state relay

40. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
50-65
A missing air filter+improper rotation of the indoor blower+blower too small
An increase of air leakage from ductwork
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

41. What is the purpose of a CPR valve...
Lack of airflow
Low discharge pressure - high suction pressure - and low amp draw
It is used to control refrigerant pressure in the compressor crankcase
The discharge pressure increases and the amperage increases

42. What problem or problems can cause low discharge and suction pressure...
A missing air filter+improper rotation of the indoor blower+blower too small
Contains a solenoid coil and one or more sets of contacts
An overcharged system
An undercharged system+insufficient airflow over the evaporator coil

43. 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
An increase in low-side pressure
Lack of airflow
Technician B
Both technicians are incorrect

44. A restricted air filter in an air conditioning system can be identified by...
An open internal overload protector
An increase of air leakage from ductwork
Low superheat
Technician B

45. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Run with high head and high suction pressure
('Y' and 'C') and ('G' and 'C')
Technician B

46. 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
Current in the compressor circuit
Contains a solenoid coil and one or more sets of contacts
Both technicians are correct
Technician B

47. Which of the following could be the cause for a system's discharge and suction pressure being low...
A bad thermostat
A restricted metering device
A blown fuse
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

48. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The sight glass is full of liquid+the sight glass is full of gas
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
The superheat increases and the subcooling decreases

49. What is the purpose of a CPR valve...
A blown fuse
It is used to control refrigerant pressure in the compressor crankcase
It keeps a constant superheat in the evaporator
An undercharged system+insufficient airflow over the evaporator coil

50. 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
The discharge pressure increases and the amperage increases
Technician B
Broken rings+broken valves+seized bearings
An uninsulated suction line and a restricted metering device