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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. What component is most often the cause of a start capacitor failure...
A start relay
Clean the condenser coil
Broken rings+broken valves+seized bearings
Run with high head and high suction pressure

2. 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
A start capacitor and a solid-state relay
High suction pressure and low superheat
Technician A is correct
The sensing bulb at a lower temperature than the valve body

3. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Technician B
A plugged filter drier
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The external equalizer could be plugged

4. What causes the automatic expansion valve to close...
Clean the condenser coil
Run with high head and high suction pressure
A plugged filter drier
An increase in low-side pressure

5. What is the purpose of a CPR valve...
The system has been overcharged+The system has air trapped in the condenser
It is used to control refrigerant pressure in the compressor crankcase
An open internal overload protector
Flooding the condenser - cycling condenser fans - and dampering condenser air

6. 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
A blown fuse
A start capacitor and a solid-state relay
The system has been overcharged+The system has air trapped in the condenser
Technician A

7. A hard-start kit for an air conditioning system...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Increases starting torque

8. 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 restricted metering device
Broken rings+broken valves+seized bearings
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Current in the compressor circuit

9. Superheat is found in an air conditioning system in the...
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
Evaporator and compressor

10. 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
Technician B
The external equalizer could be plugged
Bad compressor valve
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

11. 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
Both technicians are incorrect
Technician B
'G' to 'C'
20 to 30

12. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Condenser fans operating during a low ambient condition and a low suction pressure
Run with high head and high suction pressure

13. Which of the following can cause excessive subcooling...
An overcharged system
Technician B
High superheat and low discharge pressure
An open internal overload protector

14. If 24 volts are present to the contactor coil on an air conditioning system and the condenser fan or compressor is inoperative - which of the following could be at fault...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
A blown fuse
Technician A

15. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
A bad thermostat
Technician B
An acid-core suction line drier
It is used to control refrigerant pressure in the compressor crankcase

16. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
The sight glass is full of liquid+the sight glass is full of gas
3 psig
An increase of air leakage from ductwork
Flooding the condenser - cycling condenser fans - and dampering condenser air

17. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A start capacitor and a solid-state relay
An acid-core suction line drier
An overcharged system

18. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
The sight glass is full of liquid+the sight glass is full of gas
Low voltage and a faulty start relay
Low superheat

19. What component is most often the cause of a start capacitor failure...
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Bad compressor valve
A start relay

20. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
The sensing bulb at a lower temperature than the valve body
High suction pressure and low superheat
An uninsulated suction line and a restricted metering device

21. 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
A start capacitor and a solid-state relay
Technician B
An open internal overload protector
A dirty condenser - recirculation of condenser air - and a defective condenser fan

22. 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
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A low refrigerant charge

23. What are the operating pressures of an oil pressure safety switch...
Both technicians are incorrect
The oil pump pressure and the crankcase pressure
An increase in suction pressure and an increase in discharge pressure
An increase in low-side pressure

24. 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
Low superheat
'G' to 'C'
Technician A
Clean the condenser coil

25. 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
3 psig
Low discharge pressure - high suction pressure - and low amp draw
Low discharge pressure - high suction pressure - and low amp draw

26. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
An undercharged system+insufficient airflow over the evaporator coil
The oil pump pressure and the crankcase pressure
A plugged filter drier
An increase in low-side pressure

27. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A start relay
An open internal overload protector
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

28. Air filters should be replaced...
Whenever necessary
An undercharged system+insufficient airflow over the evaporator coil
Current in the compressor circuit
A low refrigerant charge

29. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Technician B
Evaporator and compressor
3 psig
Bad compressor valve

30. A system that uses a thermal electric expansion valve...
An overcharged system
It would cause the low-side pressure to decrease
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A defective circuit breaker

31. What type of problems can be caused by an oversized air conditioning system...
20 to 30
A restricted metering device
It keeps a constant superheat in the evaporator
Short cycling and insufficient dehumidification

32. A technician receives an air conditioning service call stating that the system is operating but isn't cooling properly. When the technician arrives - she notices that the compressor has recently been changed and it is an are-22 system. She checks the
The low-side pressure will decrease and the evaporator coil will be partially frosted
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
'G' to 'C'

33. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A restricted metering device
Both technicians are incorrect
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

34. 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...
Lack of airflow
An undercharged system+insufficient airflow over the evaporator coil
The superheat increases and the subcooling decreases
Low voltage and a faulty start relay

35. A commercial customer calls on a 90
The low-side pressure will decrease and the evaporator coil will be partially frosted
The system has been overcharged+The system has air trapped in the condenser
Both technicians are incorrect
A start capacitor and a solid-state relay

36. What are the operating pressures of an oil pressure safety switch...
The system has been overcharged+The system has air trapped in the condenser
Lack of airflow
The oil pump pressure and the crankcase pressure
Run with high head and high suction pressure

37. The internal overload of an air conditioning compressor senses winding temperature and...
A restricted metering device
A start relay
Current in the compressor circuit
A missing air filter+improper rotation of the indoor blower+blower too small

38. Insufficient airflow can be caused by...
The internal overload is opened
An increase of air leakage from ductwork
The external equalizer could be plugged
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

39. 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
A blown fuse
Condenser fans operating during a low ambient condition and a low suction pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted

40. A liquid-charged TXV bulb will...
A restricted metering device
An increase in low-side pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Always have some liquid present in the bulb and diaphragm

41. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
It is used to control refrigerant pressure in the compressor crankcase
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A missing air filter+improper rotation of the indoor blower+blower too small
The system has been overcharged+The system has air trapped in the condenser

42. A system that is operating with a clear sight glass shows...
Rise more than normal
Short cycling and insufficient dehumidification
The superheat will increase and the low-side pressure will decrease
The sight glass is full of liquid+the sight glass is full of gas

43. What is the purpose of the TXV...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The oil pump pressure and the crankcase pressure
Technician B
It keeps a constant superheat in the evaporator

44. A liquid-charged TXV bulb will...
Clean the condenser coil
Short cycling and insufficient dehumidification
A start capacitor and a solid-state relay
Always have some liquid present in the bulb and diaphragm

45. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
Low voltage and a faulty start relay
Both technicians are correct
Run with high head and high suction pressure

46. 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
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
('Y' and 'C') and ('G' and 'C')

47. 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
50-65
The discharge pressure increases and the amperage increases
It is used to control refrigerant pressure in the compressor crankcase
Technician B

48. 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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49. Air filters should be replaced...
Whenever necessary
Evaporator and compressor
('Y' and 'C') and ('G' and 'C')
A vacuum test+oil traces around fittings+soap bubble solution

50. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An overcharged system
Broken rings+broken valves+seized bearings
Technician A