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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 are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An uninsulated TXV sensing bulb
Both technicians are incorrect
An undercharge and low ambient conditions
High suction pressure and low superheat

2. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Bad compressor valve
A plugged filter drier
An increase in suction pressure and an increase in discharge pressure

3. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
50-65
An undercharge and low ambient conditions
A bad thermostat
Always have some liquid present in the bulb and diaphragm

4. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
Current in the compressor circuit
Current in the compressor circuit
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

5. Which of the following could be the cause for a system's discharge and suction pressure being low...
Low voltage and a faulty start relay
A low refrigerant charge
An increase in suction pressure and an increase in discharge pressure
A restricted metering device

6. A system that is operating with a clear sight glass shows...
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
The oil pump pressure and the crankcase pressure
Current in the compressor circuit

7. 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
An increase of air leakage from ductwork
An increase in suction pressure and an increase in discharge pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The external equalizer could be plugged

8. 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
A missing air filter+improper rotation of the indoor blower+blower too small
Whenever necessary

9. What is the purpose of the TXV...
Run with high head and high suction pressure
An undercharged system+insufficient airflow over the evaporator coil
Technician B
It keeps a constant superheat in the evaporator

10. What are common methods that are used for leak-testing a system...
An increase of air leakage from ductwork
Low voltage and a faulty start relay
A vacuum test+oil traces around fittings+soap bubble solution
A missing air filter+improper rotation of the indoor blower+blower too small

11. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Increases starting torque
Run with high head and high suction pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

12. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Technician B
High suction pressure and low superheat
A defective circuit breaker
An increase in low-side pressure

13. 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
An uninsulated suction line and a restricted metering device
Short cycling and insufficient dehumidification
The external equalizer could be plugged

14. A restricted air filter in an air conditioning system can be identified by...
A plugged filter drier
Contains a solenoid coil and one or more sets of contacts
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Low superheat

15. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
Both technicians are correct
An overcharged system
Condenser fans operating during a low ambient condition and a low suction pressure

16. A hard-start kit consists of...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
A start capacitor and a solid-state relay
An acid-core suction line drier

17. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Both technicians are incorrect
Both technicians are incorrect
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are correct

18. Which of the following will cause excessive discharge pressures on an air conditioning system...
Current in the compressor circuit
High superheat and low discharge pressure
It would cause the low-side pressure to decrease
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

19. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A blown fuse
Rise more than normal
Lack of airflow

20. 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...
The sight glass is full of liquid+the sight glass is full of gas
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Low voltage and a faulty start relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

21. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The system has been overcharged+The system has air trapped in the condenser
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A defective circuit breaker

22. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Increases starting torque
The external equalizer could be plugged

23. 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
Condenser fans operating during a low ambient condition and a low suction pressure
Broken rings+broken valves+seized bearings
Low discharge pressure - high suction pressure - and low amp draw
A start capacitor and a solid-state relay

24. Which of the following can cause excessive subcooling...
An overcharged system
Both technicians are incorrect
('Y' and 'C') and ('G' and 'C')
A defective circuit breaker

25. 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...
The superheat increases and the subcooling decreases
It keeps a constant superheat in the evaporator
Increases starting torque
Condenser fans operating during a low ambient condition and a low suction pressure

26. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
110-120
Flooding the condenser - cycling condenser fans - and dampering condenser air
It would cause the low-side pressure to decrease
Broken rings+broken valves+seized bearings

27. A commercial customer calls on a 90
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Low discharge pressure - high suction pressure - and low amp draw
The system has been overcharged+The system has air trapped in the condenser
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

28. 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
An undercharge and low ambient conditions
The internal overload is opened
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Dirty condenser - bent condenser fins - and air recirculating over the condenser

29. Air filters should be replaced...
High superheat and low discharge pressure
Whenever necessary
An increase in low-side pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser

30. 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
The superheat will increase and the low-side pressure will decrease
Clean the condenser coil
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

31. 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
Increases starting torque
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A missing air filter+improper rotation of the indoor blower+blower too small

32. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
It is used to control refrigerant pressure in the compressor crankcase
An increase of air leakage from ductwork
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

33. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
Short cycling and insufficient dehumidification
The internal overload is opened

34. A compressor having tight bearings would cause the current value to...
An overcharged system
Whenever necessary
The external equalizer could be plugged
Rise more than normal

35. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Current in the compressor circuit
A bad thermostat
A vacuum test+oil traces around fittings+soap bubble solution

36. 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 defective circuit breaker
An overcharged system
A restricted metering device
Technician A is correct

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...

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38. The internal overload of an air conditioning compressor senses winding temperature and...
Broken rings+broken valves+seized bearings
A sensing bulb improperly connected to the suction line
Low superheat
Current in the compressor circuit

39. Superheat is found in an air conditioning system in the...
Technician B
Evaporator and compressor
A start relay
Condenser fans operating during a low ambient condition and a low suction pressure

40. 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
Low voltage and a faulty start relay
Broken rings+broken valves+seized bearings
Technician B

41. The temperature range of the suction line from an air conditioning system should be...
Flooding the condenser - cycling condenser fans - and dampering condenser air
An undercharge and low ambient conditions
50-65
Low voltage and a faulty start relay

42. Which of the following is a common cause of an excessively low superheat on a TXV system...
Condenser fans operating during a low ambient condition and a low suction pressure
A sensing bulb improperly connected to the suction line
A restricted metering device
The sight glass is full of liquid+the sight glass is full of gas

43. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
Technician B
Broken rings+broken valves+seized bearings
A sensing bulb improperly connected to the suction line

44. Superheat is found in an air conditioning system in the...
Evaporator and compressor
A vacuum test+oil traces around fittings+soap bubble solution
The low-side pressure will decrease and the evaporator coil will be partially frosted
High suction pressure and low superheat

45. A liquid-charged TXV bulb will...
Technician B
Low superheat
Always have some liquid present in the bulb and diaphragm
The internal overload is opened

46. 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 increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B
Both technicians are incorrect
A low refrigerant charge

47. 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
A restricted metering device
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A dirty condenser - recirculation of condenser air - and a defective condenser fan

48. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A plugged filter drier
An increase in suction pressure and an increase in discharge pressure
An undercharged system+insufficient airflow over the evaporator coil
A restricted metering device

49. When using a vapor-charged TXV bulb - it is necessary to have...
A restricted metering device
Evaporator and compressor
The sensing bulb at a lower temperature than the valve body
An overcharged system

50. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A vacuum test+oil traces around fittings+soap bubble solution
Technician B
Lack of airflow
Current in the compressor circuit