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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. Air filters should be replaced...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Bad compressor valve
Whenever necessary
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

2. 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
Contains a solenoid coil and one or more sets of contacts
A blown fuse
Low discharge pressure - high suction pressure - and low amp draw
Technician A is correct

3. Which of the following could be the cause for a system's discharge and suction pressure being low...
Short cycling and insufficient dehumidification
A restricted metering device
An acid-core suction line drier
Evaporator and compressor

4. What type of problems can be caused by an oversized air conditioning system...
An uninsulated suction line and a restricted metering device
Short cycling and insufficient dehumidification
Increases starting torque
('Y' and 'C') and ('G' and 'C')

5. 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 plugged filter drier
Technician B
An uninsulated suction line and a restricted metering device
It is used to control refrigerant pressure in the compressor crankcase

6. The temperature range of the suction line from an air conditioning system should be...
An increase in suction pressure and an increase in discharge pressure
The system has been overcharged+The system has air trapped in the condenser
Lack of airflow
50-65

7. A commercial customer calls on a 90
50-65
Technician A
The system has been overcharged+The system has air trapped in the condenser
('Y' and 'C') and ('G' and 'C')

8. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Whenever necessary
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
An open internal overload protector

9. 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...
Flooding the condenser - cycling condenser fans - and dampering condenser air
The sensing bulb at a lower temperature than the valve body
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

10. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
An uninsulated suction line and a restricted metering device
An increase in suction pressure and an increase in discharge pressure
It would cause the low-side pressure to decrease

11. What are the symptoms of an air conditioning system that has a low charge...
Rise more than normal
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B

12. A compressor having tight bearings would cause the current value to...
Rise more than normal
Both technicians are correct
An uninsulated suction line and a restricted metering device
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

13. 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 system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Low voltage and a faulty start relay
The sensing bulb at a lower temperature than the valve body
High suction pressure and low superheat

14. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Rise more than normal
An increase in suction pressure and an increase in discharge pressure
20 to 30
It would cause the low-side pressure to decrease

15. The best description of a relay would be...
Evaporator and compressor
Contains a solenoid coil and one or more sets of contacts
Clean the condenser coil
3 psig

16. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
'G' to 'C'
An increase in suction pressure and an increase in discharge pressure
Always have some liquid present in the bulb and diaphragm

17. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Clean the condenser coil
It would cause the low-side pressure to decrease
The discharge pressure increases and the amperage increases
A start capacitor and a solid-state relay

18. What are two common symptoms of refrigerant leaks in an air conditioning system...
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An open internal overload protector
Partially frosted evaporator and high superheat

19. 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
A sensing bulb improperly connected to the suction line
An undercharged system+insufficient airflow over the evaporator coil
A vacuum test+oil traces around fittings+soap bubble solution

20. A system that is operating with a clear sight glass shows...
It keeps a constant superheat in the evaporator
The sight glass is full of liquid+the sight glass is full of gas
A start capacitor and a solid-state relay
Whenever necessary

21. 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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22. A hard-start kit consists of...
Partially frosted evaporator and high superheat
Technician A is correct
A start capacitor and a solid-state relay
20 to 30

23. What are three methods for controlling a system's high-side pressure during low ambient conditions...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
The sensing bulb at a lower temperature than the valve body

24. What are the symptoms of an air conditioning system that has a low charge...
Both technicians are correct
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The low-side pressure will decrease and the evaporator coil will be partially frosted
Whenever necessary

25. What problem or problems can cause low discharge and suction pressure...
The sight glass is full of liquid+the sight glass is full of gas
110-120
An undercharged system+insufficient airflow over the evaporator coil
An acid-core suction line drier

26. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The low-side pressure will decrease and the evaporator coil will be partially frosted
Lack of airflow

27. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
Rise more than normal
High suction pressure and low superheat
An uninsulated suction line and a restricted metering device

28. What is the purpose of the TXV...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It keeps a constant superheat in the evaporator
('Y' and 'C') and ('G' and 'C')
110-120

29. 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
It would cause the low-side pressure to decrease
An overcharged system
Rise more than normal
Technician B

30. 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
It would cause the low-side pressure to decrease
The discharge pressure increases and the amperage increases
The external equalizer could be plugged
Partially frosted evaporator and high superheat

31. Which of the following is a common cause of an excessively low superheat on a TXV system...
A start capacitor and a solid-state relay
The internal overload is opened
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A sensing bulb improperly connected to the suction line

32. What are three methods for controlling a system's high-side pressure during low ambient conditions...
('Y' and 'C') and ('G' and 'C')
Flooding the condenser - cycling condenser fans - and dampering condenser air
Rise more than normal
Both technicians are incorrect

33. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Technician B
Broken rings+broken valves+seized bearings
High suction pressure and low superheat
An increase in suction pressure and an increase in discharge pressure

34. What are common methods that are used for leak-testing a system...
Short cycling and insufficient dehumidification
The discharge pressure increases and the amperage increases
Both technicians are incorrect
A vacuum test+oil traces around fittings+soap bubble solution

35. What causes the automatic expansion valve to close...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The sensing bulb at a lower temperature than the valve body
Technician B
An increase in low-side pressure

36. 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
The external equalizer could be plugged
Current in the compressor circuit
Always have some liquid present in the bulb and diaphragm
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

37. 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
An open internal overload protector
110-120
A defective circuit breaker

38. What are two problems that can cause an air conditioning system to have an excessively high superheat...
It would cause the low-side pressure to decrease
Both technicians are correct
Whenever necessary
An uninsulated suction line and a restricted metering device

39. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The external equalizer could be plugged
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The superheat increases and the subcooling decreases
Low voltage and a faulty start relay

40. 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

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41. What component is most often the cause of a start capacitor failure...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Increases starting torque
A start relay

42. Which of the following will cause excessive discharge pressures on an air conditioning system...
A blown fuse
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Increases starting torque

43. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase in suction pressure and an increase in discharge pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
An uninsulated suction line and a restricted metering device

44. A liquid-charged TXV bulb will...
A bad thermostat
Always have some liquid present in the bulb and diaphragm
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician A

45. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
It would cause the low-side pressure to decrease
An undercharge and low ambient conditions
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

46. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An open internal overload protector
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
3 psig
A plugged filter drier

47. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Lack of airflow
Technician B
The discharge pressure increases and the amperage increases
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

48. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The sight glass is full of liquid+the sight glass is full of gas
It would cause the low-side pressure to decrease
A defective circuit breaker
110-120

49. A restricted air filter in an air conditioning system can be identified by...
Rise more than normal
Whenever necessary
Low superheat
Technician A

50. 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

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