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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. Superheat is found in an air conditioning system in the...
Partially frosted evaporator and high superheat
Evaporator and compressor
Technician A
Technician A

2. Which of the following is a possible cause for a compressor to overheat...
An increase in suction pressure and an increase in discharge pressure
110-120
A low refrigerant charge
An undercharge and low ambient conditions

3. Superheat is found in an air conditioning system in the...
Evaporator and compressor
Both technicians are incorrect
Technician B
Technician B

4. A system that uses a thermal electric expansion valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
High superheat and low discharge pressure
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

5. 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
Lack of airflow
Broken rings+broken valves+seized bearings
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

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 start relay
Evaporator and compressor
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician A

7. A compressor having tight bearings would cause the current value to...
An overcharged system
A defective circuit breaker
Broken rings+broken valves+seized bearings
Rise more than normal

8. When using a vapor-charged TXV bulb - it is necessary to have...
Both technicians are incorrect
The sensing bulb at a lower temperature than the valve body
A missing air filter+improper rotation of the indoor blower+blower too small
Run with high head and high suction pressure

9. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A blown fuse
('Y' and 'C') and ('G' and 'C')
20 to 30

10. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A bad thermostat
Technician B
It is used to control refrigerant pressure in the compressor crankcase
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

11. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
An uninsulated TXV sensing bulb
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure
High superheat and low discharge pressure

12. 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
Short cycling and insufficient dehumidification
It would cause the low-side pressure to decrease
Low discharge pressure - high suction pressure - and low amp draw

13. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Short cycling and insufficient dehumidification
An increase in suction pressure and an increase in discharge pressure
'G' to 'C'
Both technicians are incorrect

14. A liquid-charged TXV bulb will...
20 to 30
Always have some liquid present in the bulb and diaphragm
The internal overload is opened
A dirty condenser - recirculation of condenser air - and a defective condenser fan

15. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
A defective circuit breaker
An overcharged system
Bad compressor valve

16. 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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17. What are the operating pressures of an oil pressure safety switch...
An overcharged system
The oil pump pressure and the crankcase pressure
A vacuum test+oil traces around fittings+soap bubble solution
Whenever necessary

18. What are the symptoms of an air conditioning system that has a low charge...
50-65
Partially frosted evaporator and high superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

19. What is the purpose of the TXV...
An undercharged system+insufficient airflow over the evaporator coil
The internal overload is opened
A start capacitor and a solid-state relay
It keeps a constant superheat in the evaporator

20. Air filters should be replaced...
Technician B
Low superheat
Technician B
Whenever necessary

21. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
An overcharged system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Run with high head and high suction pressure
An acid-core suction line drier

22. 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...
A start capacitor and a solid-state relay
Short cycling and insufficient dehumidification
The internal overload is opened
An undercharge and low ambient conditions

23. 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...
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The discharge pressure increases and the amperage increases
A blown fuse

24. 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...
High superheat and low discharge pressure
Technician B
Low superheat
The external equalizer could be plugged

25. What are common methods that are used for leak-testing a system...
Low discharge pressure - high suction pressure - and low amp draw
A vacuum test+oil traces around fittings+soap bubble solution
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The sight glass is full of liquid+the sight glass is full of gas

26. 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
110-120
Technician A is correct
A blown fuse
High superheat and low discharge pressure

27. 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 low refrigerant charge
Technician A is correct
Flooding the condenser - cycling condenser fans - and dampering condenser air
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

28. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
'G' to 'C'
The system has been overcharged+The system has air trapped in the condenser
A sensing bulb improperly connected to the suction line
An acid-core suction line drier

29. 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
Technician B
It keeps a constant superheat in the evaporator
Run with high head and high suction pressure
A start relay

30. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
An open internal overload protector
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A plugged filter drier
It would cause the low-side pressure to decrease

31. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
('Y' and 'C') and ('G' and 'C')
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Contains a solenoid coil and one or more sets of contacts

32. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Increases starting torque
3 psig
An overcharged system

33. Which of the following can cause low superheat in a TXV system...
Increases starting torque
An uninsulated TXV sensing bulb
Low discharge pressure - high suction pressure - and low amp draw
A low refrigerant charge

34. 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 low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
The sight glass is full of liquid+the sight glass is full of gas
Contains a solenoid coil and one or more sets of contacts

35. A hard-start kit for an air conditioning system...
Increases starting torque
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A start capacitor and a solid-state relay
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

36. 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
An open internal overload protector
Technician B
The sight glass is full of liquid+the sight glass is full of gas
3 psig

37. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Technician B
('Y' and 'C') and ('G' and 'C')
Technician B
The discharge pressure increases and the amperage increases

38. A system that is operating with a clear sight glass shows...
An uninsulated TXV sensing bulb
The discharge pressure increases and the amperage increases
Both technicians are incorrect
The sight glass is full of liquid+the sight glass is full of gas

39. A hard-start kit consists of...
Low superheat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A start capacitor and a solid-state relay
Both technicians are incorrect

40. What causes the automatic expansion valve to close...
An uninsulated TXV sensing bulb
An increase in low-side pressure
A sensing bulb improperly connected to the suction line
Rise more than normal

41. 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
Both technicians are incorrect
Short cycling and insufficient dehumidification
An increase of air leakage from ductwork
Low discharge pressure - high suction pressure - and low amp draw

42. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A start capacitor and a solid-state relay
An overcharged system
Bad compressor valve
A plugged filter drier

43. What is the purpose of an EPR valve...
The external equalizer could be plugged
Both technicians are incorrect
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

44. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
An uninsulated TXV sensing bulb
Lack of airflow
The external equalizer could be plugged

45. What are the symptoms of an air conditioning system that has a low charge...
Whenever necessary
Always have some liquid present in the bulb and diaphragm
A vacuum test+oil traces around fittings+soap bubble solution
The low-side pressure will decrease and the evaporator coil will be partially frosted

46. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Both technicians are correct
A blown fuse
An overcharged system

47. 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 start relay
Broken rings+broken valves+seized bearings
A start relay
High suction pressure and low superheat

48. 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
Contains a solenoid coil and one or more sets of contacts
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician A is correct
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

49. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
A sensing bulb improperly connected to the suction line
Both technicians are incorrect
The oil pump pressure and the crankcase pressure

50. 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...
Low voltage and a faulty start relay
A restricted metering device
A start relay
Technician A is correct