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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. 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...
'G' to 'C'
Evaporator and compressor
High superheat and low discharge pressure
The internal overload is opened

2. 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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3. 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
('Y' and 'C') and ('G' and 'C')
It keeps a constant superheat in the evaporator

4. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An increase of air leakage from ductwork
Broken rings+broken valves+seized bearings
An open internal overload protector

5. A hard-start kit consists of...
A start capacitor and a solid-state relay
An acid-core suction line drier
A bad thermostat
An undercharged system+insufficient airflow over the evaporator coil

6. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
Current in the compressor circuit
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

7. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The system has been overcharged+The system has air trapped in the condenser
50-65
An increase in suction pressure and an increase in discharge pressure
It is used to control refrigerant pressure in the compressor crankcase

8. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
It would cause the low-side pressure to decrease
An uninsulated TXV sensing bulb
Run with high head and high suction pressure

9. 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
Increases starting torque
Both technicians are correct
20 to 30

10. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Whenever necessary
Both technicians are correct
Low discharge pressure - high suction pressure - and low amp draw
Dirty condenser - bent condenser fins - and air recirculating over the condenser

11. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Current in the compressor circuit
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The superheat will increase and the low-side pressure will decrease
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

12. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
The sight glass is full of liquid+the sight glass is full of gas
'G' to 'C'
A missing air filter+improper rotation of the indoor blower+blower too small
110-120

13. 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
A start capacitor and a solid-state relay
Technician A
Both technicians are incorrect
A dirty condenser - recirculation of condenser air - and a defective condenser fan

14. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An acid-core suction line drier
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

15. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
'G' to 'C'
A plugged filter drier
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Whenever necessary

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 common methods that are used for leak-testing a system...
Technician B
A blown fuse
('Y' and 'C') and ('G' and 'C')
A vacuum test+oil traces around fittings+soap bubble solution

18. 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
It is used to control refrigerant pressure in the compressor crankcase
Partially frosted evaporator and high superheat
Technician B
The discharge pressure increases and the amperage increases

19. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Both technicians are incorrect
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
'G' to 'C'
The sensing bulb at a lower temperature than the valve body

20. Why is it unsafe to operate an air conditioning system with a low charge...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An increase in low-side pressure
An overcharged system
('Y' and 'C') and ('G' and 'C')

21. 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
Always have some liquid present in the bulb and diaphragm
High suction pressure and low superheat
Both technicians are incorrect
Both technicians are correct

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
Increases starting torque
Technician A
The oil pump pressure and the crankcase pressure
Always have some liquid present in the bulb and diaphragm

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...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The internal overload is opened
A defective circuit breaker
A blown fuse

24. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Current in the compressor circuit
The internal overload is opened
An increase of air leakage from ductwork
Bad compressor valve

25. What are the symptoms of an air conditioning system that has a low charge...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The internal overload is opened
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted

26. A system that uses a thermal electric expansion valve...
An undercharged system+insufficient airflow over the evaporator coil
An overcharged system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A start relay

27. A hard-start kit for an air conditioning system...
50-65
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Increases starting torque
Technician A is correct

28. 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
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in low-side pressure
Technician B

29. Which of the following can cause excessive subcooling...
An overcharged system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Lack of airflow
Technician A is correct

30. What is the purpose of the TXV...
Technician B
A blown fuse
It keeps a constant superheat in the evaporator
The internal overload is opened

31. 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...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase of air leakage from ductwork
A blown fuse
It keeps a constant superheat in the evaporator

32. A restricted air filter in an air conditioning system can be identified by...
The sight glass is full of liquid+the sight glass is full of gas
The low-side pressure will decrease and the evaporator coil will be partially frosted
A defective circuit breaker
Low superheat

33. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A plugged filter drier
The sight glass is full of liquid+the sight glass is full of gas
110-120
A missing air filter+improper rotation of the indoor blower+blower too small

34. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An undercharged system+insufficient airflow over the evaporator coil
The external equalizer could be plugged
A plugged filter drier

35. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
The oil pump pressure and the crankcase pressure
An acid-core suction line drier
Clean the condenser coil
A bad thermostat

36. 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...
Technician B
It keeps a constant superheat in the evaporator
Both technicians are incorrect
High superheat and low discharge pressure

37. 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
Evaporator and compressor
An increase in low-side pressure
Clean the condenser coil
Technician A is correct

38. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Broken rings+broken valves+seized bearings
An increase in suction pressure and an increase in discharge pressure
It would cause the low-side pressure to decrease
A bad thermostat

39. 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
Increases starting torque
A blown fuse
An increase in suction pressure and an increase in discharge pressure

40. 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 correct
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A defective circuit breaker

41. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Technician B
The superheat increases and the subcooling decreases
Always have some liquid present in the bulb and diaphragm
Lack of airflow

42. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
A missing air filter+improper rotation of the indoor blower+blower too small
The internal overload is opened
An overcharged system
Low discharge pressure - high suction pressure - and low amp draw

43. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
High suction pressure and low superheat
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
'G' to 'C'
An uninsulated TXV sensing bulb

44. What are two common symptoms of refrigerant leaks in an air conditioning system...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Partially frosted evaporator and high superheat
Technician B
Broken rings+broken valves+seized bearings

45. 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
Short cycling and insufficient dehumidification
A start relay
High superheat and low discharge pressure
Technician B

46. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Low voltage and a faulty start relay
A missing air filter+improper rotation of the indoor blower+blower too small
The external equalizer could be plugged

47. When using a vapor-charged TXV bulb - it is necessary to have...
'G' to 'C'
Technician B
It is used to control refrigerant pressure in the compressor crankcase
The sensing bulb at a lower temperature than the valve body

48. The temperature range of the suction line from an air conditioning system should be...
3 psig
An acid-core suction line drier
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
50-65

49. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Partially frosted evaporator and high superheat
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
110-120
Partially frosted evaporator and high superheat

50. Which of the following will cause excessive discharge pressures on an air conditioning system...
Low discharge pressure - high suction pressure - and low amp draw
High suction pressure and low superheat
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Flooding the condenser - cycling condenser fans - and dampering condenser air