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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 liquid-charged TXV bulb will...
An open internal overload protector
Always have some liquid present in the bulb and diaphragm
Technician B
Low discharge pressure - high suction pressure - and low amp draw

2. What are two common symptoms of refrigerant leaks in an air conditioning system...
Lack of airflow
A start relay
The sight glass is full of liquid+the sight glass is full of gas
Partially frosted evaporator and high superheat

3. What are three methods for controlling a system's high-side pressure during low ambient conditions...
An overcharged system
Low discharge pressure - high suction pressure - and low amp draw
It keeps a constant superheat in the evaporator
Flooding the condenser - cycling condenser fans - and dampering condenser air

4. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
Condenser fans operating during a low ambient condition and a low suction pressure
20 to 30
An overcharged system

5. What three things can prevent an air conditioning system from releasing heat at the proper rate...
20 to 30
The internal overload is opened
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Both technicians are incorrect

6. Which of the following could be the cause for a system's discharge and suction pressure being low...
Technician B
A restricted metering device
It keeps a constant superheat in the evaporator
Evaporator and compressor

7. What is the common cause of a compressor burnout...
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
High superheat and low discharge pressure
An increase of air leakage from ductwork

8. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
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
Both technicians are correct
A start relay

9. 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
A bad thermostat
Partially frosted evaporator and high superheat
Lack of airflow
20 to 30

10. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Whenever necessary
Increases starting torque
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An undercharge and low ambient conditions

11. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An uninsulated suction line and a restricted metering device
Both technicians are incorrect
Short cycling and insufficient dehumidification

12. 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 incorrect
Technician B
Technician A is correct
Technician A

13. A hard-start kit for an air conditioning system...
Technician B
An open internal overload protector
Increases starting torque
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

14. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
It would cause the low-side pressure to decrease
Technician A
The superheat increases and the subcooling decreases
'G' to 'C'

15. 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
20 to 30
The oil pump pressure and the crankcase pressure
Run with high head and high suction pressure

16. 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...
An acid-core suction line drier
A blown fuse
Condenser fans operating during a low ambient condition and a low suction pressure
Increases starting torque

17. A hard-start kit consists of...
('Y' and 'C') and ('G' and 'C')
A start capacitor and a solid-state relay
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The internal overload is opened

18. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Run with high head and high suction pressure
Lack of airflow
It keeps a constant superheat in the evaporator
20 to 30

19. 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
50-65
Technician B
Technician A
Low superheat

20. Superheat is found in an air conditioning system in the...
Both technicians are incorrect
Evaporator and compressor
Technician B
An increase in low-side pressure

21. 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
Broken rings+broken valves+seized bearings
Low discharge pressure - high suction pressure - and low amp draw
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

22. 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
The internal overload is opened
Both technicians are incorrect
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
High suction pressure and low superheat

23. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Run with high head and high suction pressure
High suction pressure and low superheat
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A start relay

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
Technician B
A bad thermostat
An increase of air leakage from ductwork
A start capacitor and a solid-state relay

25. The best description of a relay would be...
'G' to 'C'
The oil pump pressure and the crankcase pressure
Contains a solenoid coil and one or more sets of contacts
Bad compressor valve

26. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Rise more than normal
An increase in low-side pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An uninsulated suction line and a restricted metering device

27. A commercial customer calls on a 90
Technician B
An acid-core suction line drier
The system has been overcharged+The system has air trapped in the condenser
It is used to control refrigerant pressure in the compressor crankcase

28. 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
Technician B
The sight glass is full of liquid+the sight glass is full of gas
An overcharged system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

29. 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
An undercharged system+insufficient airflow over the evaporator coil
Technician B
Always have some liquid present in the bulb and diaphragm
An increase of air leakage from ductwork

30. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
A vacuum test+oil traces around fittings+soap bubble solution
A plugged filter drier
A restricted metering device

31. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
Lack of airflow
Both technicians are correct
A bad thermostat

32. 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
A bad thermostat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The external equalizer could be plugged

33. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
A bad thermostat
Low discharge pressure - high suction pressure - and low amp draw
Short cycling and insufficient dehumidification
Dirty condenser - bent condenser fins - and air recirculating over the condenser

34. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Broken rings+broken valves+seized bearings
Technician B
An undercharge and low ambient conditions
A low refrigerant charge

35. Air filters should be replaced...
Whenever necessary
High superheat and low discharge pressure
The discharge pressure increases and the amperage increases
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

36. What component is most often the cause of a start capacitor failure...
Both technicians are incorrect
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted
A start relay

37. What causes the automatic expansion valve to close...
The superheat increases and the subcooling decreases
('Y' and 'C') and ('G' and 'C')
An increase in low-side pressure
3 psig

38. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
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
Short cycling and insufficient dehumidification

39. Which of the following is a possible cause for a compressor to overheat...
The external equalizer could be plugged
A bad thermostat
A low refrigerant charge
('Y' and 'C') and ('G' and 'C')

40. A hard-start kit for an air conditioning system...
Increases starting torque
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Low superheat
Both technicians are incorrect

41. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
110-120
An undercharged system+insufficient airflow over the evaporator coil

42. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
The external equalizer could be plugged
3 psig
Contains a solenoid coil and one or more sets of contacts
Dirty condenser - bent condenser fins - and air recirculating over the condenser

43. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Current in the compressor circuit
The system has been overcharged+The system has air trapped in the condenser
A sensing bulb improperly connected to the suction line

44. Which of the following can cause excessive subcooling...
Clean the condenser coil
An overcharged system
Evaporator and compressor
Clean the condenser coil

45. 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
3 psig
The sensing bulb at a lower temperature than the valve body
Technician B
Lack of airflow

46. A hard-start kit consists of...
It is used to control refrigerant pressure in the compressor crankcase
Both technicians are correct
A start capacitor and a solid-state relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

47. A restricted air filter in an air conditioning system can be identified by...
Evaporator and compressor
Run with high head and high suction pressure
'G' to 'C'
Low superheat

48. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Broken rings+broken valves+seized bearings
A defective circuit breaker
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B

49. 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
Technician B
Both technicians are correct
Technician B

50. 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 discharge pressure increases and the amperage increases
A blown fuse
Always have some liquid present in the bulb and diaphragm