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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. 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
The internal overload is opened
An uninsulated TXV sensing bulb
An undercharge and low ambient conditions

2. Which of the following will cause excessive discharge pressures on an air conditioning system...
A bad thermostat
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An overcharged system

3. The temperature range of the suction line from an air conditioning system should be...
Contains a solenoid coil and one or more sets of contacts
It is used to control refrigerant pressure in the compressor crankcase
Rise more than normal
50-65

4. A party-store owner tried to adjust the water valve on his water-cooled condensing unit - then he called for assistance from an HVAC/are service technician. It was found that when servicing the unit - the outlet water temperature was too low. Technic
Technician B
An increase in suction pressure and an increase in discharge pressure
Both technicians are incorrect
A restricted metering device

5. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Technician B
A plugged filter drier
A blown fuse
An overcharged system

6. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Technician B
Low voltage and a faulty start relay
The external equalizer could be plugged
A plugged filter drier

7. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Technician B
An undercharge and low ambient conditions
Condenser fans operating during a low ambient condition and a low suction pressure
An overcharged system

8. 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
Low superheat
The internal overload is opened
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B

9. Air filters should be replaced...
A bad thermostat
Technician B
Whenever necessary
A start capacitor and a solid-state relay

10. Insufficient airflow can be caused by...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A plugged filter drier
An increase of air leakage from ductwork
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

11. A liquid-charged TXV bulb will...
Run with high head and high suction pressure
An uninsulated suction line and a restricted metering device
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Always have some liquid present in the bulb and diaphragm

12. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
An increase in low-side pressure
The superheat increases and the subcooling decreases
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

13. 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...
Technician A
A restricted metering device
An acid-core suction line drier
Low voltage and a faulty start relay

14. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
An increase of air leakage from ductwork
The sight glass is full of liquid+the sight glass is full of gas
'G' to 'C'

15. 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...
Both technicians are correct
High superheat and low discharge pressure
Clean the condenser coil
A missing air filter+improper rotation of the indoor blower+blower too small

16. Which of the following is a common cause of an excessively low superheat on a TXV system...
The sensing bulb at a lower temperature than the valve body
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A sensing bulb improperly connected to the suction line
Technician A

17. What is the purpose of the TXV...
The superheat increases and the subcooling decreases
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
It keeps a constant superheat in the evaporator
Technician B

18. What component is most often the cause of a start capacitor failure...
The oil pump pressure and the crankcase pressure
Technician B
Clean the condenser coil
A start relay

19. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Always have some liquid present in the bulb and diaphragm
An uninsulated TXV sensing bulb
Run with high head and high suction pressure
Current in the compressor circuit

20. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
'G' to 'C'
The superheat increases and the subcooling decreases
An undercharged system+insufficient airflow over the evaporator coil
An increase in low-side pressure

21. What are the symptoms of an air conditioning system that has a low charge...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An overcharged system
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The low-side pressure will decrease and the evaporator coil will be partially frosted

22. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
An overcharged system
Increases starting torque
Low discharge pressure - high suction pressure - and low amp draw
Both technicians are correct

23. Which of the following can cause low superheat in a TXV system...
An open internal overload protector
Condenser fans operating during a low ambient condition and a low suction pressure
An uninsulated TXV sensing bulb
The superheat will increase and the low-side pressure will decrease

24. A compressor having tight bearings would cause the current value to...
A blown fuse
Rise more than normal
A start relay
The internal overload is opened

25. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It would cause the low-side pressure to decrease
Technician B
The discharge pressure increases and the amperage increases
An open internal overload protector

26. A liquid-charged TXV bulb will...
110-120
A start relay
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Always have some liquid present in the bulb and diaphragm

27. A customer calls with an insufficient cooling complaint on a 90
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An increase in low-side pressure
A start relay

28. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An undercharge and low ambient conditions
Lack of airflow

29. What are two common symptoms of refrigerant leaks in an air conditioning system...
An open internal overload protector
Partially frosted evaporator and high superheat
Clean the condenser coil
The sensing bulb at a lower temperature than the valve body

30. What problem or problems can cause low discharge and suction pressure...
Always have some liquid present in the bulb and diaphragm
It is used to control refrigerant pressure in the compressor crankcase
Both technicians are incorrect
An undercharged system+insufficient airflow over the evaporator coil

31. 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
Technician B
Current in the compressor circuit
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

32. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Low superheat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Partially frosted evaporator and high superheat
A plugged filter drier

33. 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
It would cause the low-side pressure to decrease
High superheat and low discharge pressure
Technician B
An acid-core suction line drier

34. 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...
An uninsulated TXV sensing bulb
Flooding the condenser - cycling condenser fans - and dampering condenser air
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
('Y' and 'C') and ('G' and 'C')

35. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The internal overload is opened
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An increase in low-side pressure

36. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Technician B
The discharge pressure increases and the amperage increases
Low discharge pressure - high suction pressure - and low amp draw
Bad compressor valve

37. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
It would cause the low-side pressure to decrease
Dirty condenser - bent condenser fins - and air recirculating over the condenser

38. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
An overcharged system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

39. 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
3 psig
High suction pressure and low superheat
Always have some liquid present in the bulb and diaphragm
Technician B

40. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
Both technicians are correct
It is used to control refrigerant pressure in the compressor crankcase
Partially frosted evaporator and high superheat

41. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Low discharge pressure - high suction pressure - and low amp draw
The discharge pressure increases and the amperage increases
Lack of airflow
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

42. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Technician B
Current in the compressor circuit
An undercharge and low ambient conditions
Flooding the condenser - cycling condenser fans - and dampering condenser air

43. 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
Whenever necessary
An overcharged system
Rise more than normal

44. 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
A defective circuit breaker
A low refrigerant charge
A dirty condenser - recirculation of condenser air - and a defective condenser fan
('Y' and 'C') and ('G' and 'C')

45. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Clean the condenser coil
The external equalizer could be plugged
An undercharged system+insufficient airflow over the evaporator coil
A missing air filter+improper rotation of the indoor blower+blower too small

46. 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
A bad thermostat
It is used to control refrigerant pressure in the compressor crankcase
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Broken rings+broken valves+seized bearings

47. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A low refrigerant charge
A blown fuse
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Run with high head and high suction pressure

48. A commercial customer calls on a 90
Technician B
An acid-core suction line drier
The system has been overcharged+The system has air trapped in the condenser
Bad compressor valve

49. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A sensing bulb improperly connected to the suction line
An increase in suction pressure and an increase in discharge pressure
Both technicians are incorrect
An undercharged system+insufficient airflow over the evaporator coil

50. 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
An acid-core suction line drier
It would cause the low-side pressure to decrease
It is used to control refrigerant pressure in the compressor crankcase

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NATE Air Conditioning Troubleshooting

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