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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. A hard-start kit for an air conditioning system...
Increases starting torque
Always have some liquid present in the bulb and diaphragm
Partially frosted evaporator and high superheat
3 psig

2. What are the symptoms of a TXV air conditioning system if it has lost its charge...
An acid-core suction line drier
The superheat will increase and the low-side pressure will decrease
Clean the condenser coil
The sight glass is full of liquid+the sight glass is full of gas

3. What is the purpose of an EPR valve...
Technician B
Bad compressor valve
A sensing bulb improperly connected to the suction line
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

4. 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...
Partially frosted evaporator and high superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An uninsulated TXV sensing bulb
High superheat and low discharge pressure

5. 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
'G' to 'C'
An open internal overload protector
A blown fuse

6. Which of the following can cause low superheat in a TXV system...
Always have some liquid present in the bulb and diaphragm
An uninsulated TXV sensing bulb
Both technicians are correct
Run with high head and high suction pressure

7. What are two common symptoms of refrigerant leaks in an air conditioning system...
Run with high head and high suction pressure
Partially frosted evaporator and high superheat
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician A is correct

8. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
Low superheat
Lack of airflow
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

9. A compressor having tight bearings would cause the current value to...
Technician A
An overcharged system
Condenser fans operating during a low ambient condition and a low suction pressure
Rise more than normal

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 A is correct
An undercharge and low ambient conditions
The external equalizer could be plugged
The oil pump pressure and the crankcase pressure

11. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Technician B
The system has been overcharged+The system has air trapped in the condenser
It would cause the low-side pressure to decrease
A plugged filter drier

12. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Both technicians are incorrect
An undercharged system+insufficient airflow over the evaporator coil
A missing air filter+improper rotation of the indoor blower+blower too small
The sight glass is full of liquid+the sight glass is full of gas

13. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
The external equalizer could be plugged
Condenser fans operating during a low ambient condition and a low suction pressure
An acid-core suction line drier

14. What causes the automatic expansion valve to close...
Current in the compressor circuit
A plugged filter drier
Condenser fans operating during a low ambient condition and a low suction pressure
An increase in low-side pressure

15. Which of the following is a common cause of an excessively low superheat on a TXV system...
It is used to control refrigerant pressure in the compressor crankcase
3 psig
('Y' and 'C') and ('G' and 'C')
A sensing bulb improperly connected to the suction line

16. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
High suction pressure and low superheat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
High superheat and low discharge pressure

17. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
The system has been overcharged+The system has air trapped in the condenser
An uninsulated suction line and a restricted metering device
3 psig

18. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
An increase in low-side pressure
A restricted metering device
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

19. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Run with high head and high suction pressure
Technician B
The external equalizer could be plugged

20. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Low discharge pressure - high suction pressure - and low amp draw
The internal overload is opened
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B

21. Which of the following can cause excessive subcooling...
A low refrigerant charge
20 to 30
High suction pressure and low superheat
An overcharged system

22. 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
Bad compressor valve
Clean the condenser coil
Technician B
The sight glass is full of liquid+the sight glass is full of gas

23. What type of problems can be caused by an oversized air conditioning system...
A start relay
An increase of air leakage from ductwork
Short cycling and insufficient dehumidification
High suction pressure and low superheat

24. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The internal overload is opened
It keeps a constant superheat in the evaporator
Technician B

25. When using a vapor-charged TXV bulb - it is necessary to have...
Both technicians are correct
Flooding the condenser - cycling condenser fans - and dampering condenser air
The discharge pressure increases and the amperage increases
The sensing bulb at a lower temperature than the valve body

26. 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
An undercharge and low ambient conditions
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An uninsulated TXV sensing bulb

27. 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
'G' to 'C'
Clean the condenser coil
20 to 30
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

28. What are the operating pressures of an oil pressure safety switch...
Technician B
The oil pump pressure and the crankcase pressure
It is used to control refrigerant pressure in the compressor crankcase
Technician B

29. The internal overload of an air conditioning compressor senses winding temperature and...
Always have some liquid present in the bulb and diaphragm
Current in the compressor circuit
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

30. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
An increase in low-side pressure
Low discharge pressure - high suction pressure - and low amp draw
A sensing bulb improperly connected to the suction line
Technician B

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 blown fuse
Technician A
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A plugged filter drier

32. What is the common cause of a compressor burnout...
Evaporator and compressor
'G' to 'C'
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
20 to 30

33. 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
20 to 30
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A defective circuit breaker
An undercharge and low ambient conditions

34. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An uninsulated suction line and a restricted metering device
Run with high head and high suction pressure

35. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
Evaporator and compressor
Both technicians are incorrect
The sensing bulb at a lower temperature than the valve body

36. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The sight glass is full of liquid+the sight glass is full of gas
Bad compressor valve
The low-side pressure will decrease and the evaporator coil will be partially frosted

37. 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
Low voltage and a faulty start relay
An uninsulated TXV sensing bulb
An open internal overload protector
An increase of air leakage from ductwork

38. 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
It keeps a constant superheat in the evaporator
Contains a solenoid coil and one or more sets of contacts
An overcharged system

39. 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
An uninsulated suction line and a restricted metering device
A defective circuit breaker
Bad compressor valve
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

40. An air conditioning system that uses a fan center has an inoperable indoor blower. When the thermostat is set for cooling and dialed below room temperature - a test with the voltmeter shows that there is 24 volts across terminals 'are' and 'G' at the
An overcharged system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
High superheat and low discharge pressure
A bad thermostat

41. A compressor having tight bearings would cause the current value to...
A sensing bulb improperly connected to the suction line
Rise more than normal
It is used to control refrigerant pressure in the compressor crankcase
Technician A

42. Insufficient airflow can be caused by...
The internal overload is opened
Low superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An increase of air leakage from ductwork

43. 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...
Low superheat
An open internal overload protector
('Y' and 'C') and ('G' and 'C')
Technician B

44. A system that is operating with a clear sight glass shows...
Short cycling and insufficient dehumidification
The sight glass is full of liquid+the sight glass is full of gas
A defective circuit breaker
Low voltage and a faulty start relay

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
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A restricted metering device
Both technicians are correct

46. What are common methods that are used for leak-testing a system...
The oil pump pressure and the crankcase pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It would cause the low-side pressure to decrease
A vacuum test+oil traces around fittings+soap bubble solution

47. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A start relay
Bad compressor valve
An increase in suction pressure and an increase in discharge pressure

48. 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
An acid-core suction line drier
The superheat increases and the subcooling decreases
Broken rings+broken valves+seized bearings
Both technicians are incorrect

49. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
50-65
3 psig
A plugged filter drier
110-120

50. A hard-start kit consists of...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A start capacitor and a solid-state relay
The sensing bulb at a lower temperature than the valve body
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

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