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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 problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
The sensing bulb at a lower temperature than the valve body
Low discharge pressure - high suction pressure - and low amp draw
Low superheat

2. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A defective circuit breaker
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It is used to control refrigerant pressure in the compressor crankcase
High suction pressure and low superheat

3. A customer calls with an insufficient cooling complaint on a 90
Short cycling and insufficient dehumidification
Technician B
An undercharged system+insufficient airflow over the evaporator coil
A defective circuit breaker

4. 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 bad thermostat
The external equalizer could be plugged
Both technicians are incorrect
An open internal overload protector

5. 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...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
('Y' and 'C') and ('G' and 'C')

6. Why is it unsafe to operate an air conditioning system with a low charge...
Technician A is correct
An overcharged system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The superheat will increase and the low-side pressure will decrease

7. 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
Increases starting torque
20 to 30
A blown fuse

8. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
An overcharged system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Lack of airflow
It keeps a constant superheat in the evaporator

9. 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
Technician A
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
It is used to control refrigerant pressure in the compressor crankcase
The internal overload is opened

10. Which of the following is a common cause of an excessively low superheat on a TXV system...
An undercharged system+insufficient airflow over the evaporator coil
Technician A is correct
A sensing bulb improperly connected to the suction line
A dirty condenser - recirculation of condenser air - and a defective condenser fan

11. What are the symptoms of a TXV air conditioning system if it has lost its charge...
An uninsulated suction line and a restricted metering device
A low refrigerant charge
The superheat will increase and the low-side pressure will decrease
A vacuum test+oil traces around fittings+soap bubble solution

12. A hard-start kit consists of...
Always have some liquid present in the bulb and diaphragm
Evaporator and compressor
Low superheat
A start capacitor and a solid-state relay

13. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
A low refrigerant charge
An uninsulated suction line and a restricted metering device
A start relay

14. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Always have some liquid present in the bulb and diaphragm
('Y' and 'C') and ('G' and 'C')
A restricted metering device

15. Superheat is found in an air conditioning system in the...
Technician B
Evaporator and compressor
A start capacitor and a solid-state relay
Increases starting torque

16. 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
3 psig
An acid-core suction line drier
An open internal overload protector
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

17. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An uninsulated TXV sensing bulb
The superheat increases and the subcooling decreases
A low refrigerant charge
Technician B

18. Air filters should be replaced...
Lack of airflow
Short cycling and insufficient dehumidification
Both technicians are incorrect
Whenever necessary

19. What is the purpose of the TXV...
A defective circuit breaker
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
It keeps a constant superheat in the evaporator

20. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A bad thermostat
Low discharge pressure - high suction pressure - and low amp draw
The sensing bulb at a lower temperature than the valve body

21. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
Increases starting torque
Rise more than normal
Technician B
An uninsulated suction line and a restricted metering device

22. 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
A plugged filter drier
Clean the condenser coil
An undercharge and low ambient conditions
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

23. What are the operating pressures of an oil pressure safety switch...
An increase in suction pressure and an increase in discharge pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B
The oil pump pressure and the crankcase pressure

24. A hard-start kit for an air conditioning system...
Low voltage and a faulty start relay
Increases starting torque
The discharge pressure increases and the amperage increases
Always have some liquid present in the bulb and diaphragm

25. 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
Always have some liquid present in the bulb and diaphragm
The sight glass is full of liquid+the sight glass is full of gas
Technician B

26. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A low refrigerant charge
A defective circuit breaker
High superheat and low discharge pressure
Lack of airflow

27. A hard-start kit for an air conditioning system...
Increases starting torque
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The external equalizer could be plugged

28. Which of the following can cause excessive subcooling...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An overcharged system
A plugged filter drier
50-65

29. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An acid-core suction line drier
The sight glass is full of liquid+the sight glass is full of gas
An undercharged system+insufficient airflow over the evaporator coil
An undercharge and low ambient conditions

30. 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 sensing bulb at a lower temperature than the valve body
An increase in suction pressure and an increase in discharge pressure
Both technicians are correct
'G' to 'C'

31. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
20 to 30
Whenever necessary
A restricted metering device
A plugged filter drier

32. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Short cycling and insufficient dehumidification
Low discharge pressure - high suction pressure - and low amp draw
A start capacitor and a solid-state relay
The sight glass is full of liquid+the sight glass is full of gas

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
The internal overload is opened
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
50-65

34. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
('Y' and 'C') and ('G' and 'C')
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

35. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An open internal overload protector

36. 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
An increase of air leakage from ductwork
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
Evaporator and compressor

37. 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...
('Y' and 'C') and ('G' and 'C')
The sensing bulb at a lower temperature than the valve body
Technician B
Contains a solenoid coil and one or more sets of contacts

38. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Low superheat
A start capacitor and a solid-state relay
An open internal overload protector
Flooding the condenser - cycling condenser fans - and dampering condenser air

39. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Broken rings+broken valves+seized bearings
('Y' and 'C') and ('G' and 'C')
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Increases starting torque

40. 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 oil pump pressure and the crankcase pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The low-side pressure will decrease and the evaporator coil will be partially frosted
An uninsulated suction line and a restricted metering device

41. Which of the following could be the cause for a system's discharge and suction pressure being low...
50-65
It would cause the low-side pressure to decrease
A restricted metering device
Broken rings+broken valves+seized bearings

42. A commercial customer calls complaining that her rooftop air conditioning system is not operating. The technician arrives on the job and sets the thermostat to cooling - then notices that the indoor fan is not operating. The technician then sets the
Broken rings+broken valves+seized bearings
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
'G' to 'C'
Short cycling and insufficient dehumidification

43. What is the purpose of a CPR valve...
An increase in low-side pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An uninsulated TXV sensing bulb
It is used to control refrigerant pressure in the compressor crankcase

44. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
3 psig
A sensing bulb improperly connected to the suction line
Current in the compressor circuit

45. A restricted air filter in an air conditioning system can be identified by...
Short cycling and insufficient dehumidification
Low superheat
Run with high head and high suction pressure
A plugged filter drier

46. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
An overcharged system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
3 psig
An undercharged system+insufficient airflow over the evaporator coil

47. Which of the following is a possible cause for a compressor to overheat...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A start relay
Low voltage and a faulty start relay
A low refrigerant charge

48. 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
Both technicians are incorrect
Partially frosted evaporator and high superheat
An undercharge and low ambient conditions
Technician B

49. Which of the following will cause excessive discharge pressures on an air conditioning system...
Both technicians are incorrect
Run with high head and high suction pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Condenser fans operating during a low ambient condition and a low suction pressure

50. The internal overload of an air conditioning compressor senses winding temperature and...
An open internal overload protector
Current in the compressor circuit
An increase in low-side pressure
Condenser fans operating during a low ambient condition and a low suction pressure

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NATE Air Conditioning Troubleshooting

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