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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 customer calls with an insufficient cooling complaint on a 90
It would cause the low-side pressure to decrease
The external equalizer could be plugged
Technician B
The oil pump pressure and the crankcase pressure

2. The technician observes that the compressor is not operating. The compressor windings read 5 ohms start to run - run to common is opened - and start to common is opened. The technician concludes that...
Technician A
The internal overload is opened
The discharge pressure increases and the amperage increases
Technician B

3. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
110-120
Condenser fans operating during a low ambient condition and a low suction pressure
The external equalizer could be plugged

4. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Evaporator and compressor
Whenever necessary

5. 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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6. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Low discharge pressure - high suction pressure - and low amp draw
Both technicians are incorrect
An uninsulated suction line and a restricted metering device
High suction pressure and low superheat

7. Which of the following is a possible cause for a compressor to overheat...
3 psig
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A low refrigerant charge

8. 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
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
Technician A
Broken rings+broken valves+seized bearings

9. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Both technicians are incorrect
An acid-core suction line drier
The superheat will increase and the low-side pressure will decrease
Technician B

10. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
High suction pressure and low superheat
Rise more than normal
It keeps a constant superheat in the evaporator

11. A system that uses a thermal electric expansion valve...
A plugged filter drier
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An increase of air leakage from ductwork
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

12. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
A blown fuse
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan

13. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small
Flooding the condenser - cycling condenser fans - and dampering condenser air

14. Which of the following can cause excessive subcooling...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An overcharged system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The sensing bulb at a lower temperature than the valve body

15. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Broken rings+broken valves+seized bearings
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Both technicians are incorrect

16. Insufficient airflow can be caused by...
A missing air filter+improper rotation of the indoor blower+blower too small
An increase of air leakage from ductwork
The system has been overcharged+The system has air trapped in the condenser
An undercharged system+insufficient airflow over the evaporator coil

17. 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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18. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Short cycling and insufficient dehumidification
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Both technicians are incorrect

19. A hard-start kit for an air conditioning system...
20 to 30
A start relay
Increases starting torque
Whenever necessary

20. What component is most often the cause of a start capacitor failure...
('Y' and 'C') and ('G' and 'C')
The low-side pressure will decrease and the evaporator coil will be partially frosted
A start relay
Increases starting torque

21. A hard-start kit consists of...
A defective circuit breaker
A start capacitor and a solid-state relay
('Y' and 'C') and ('G' and 'C')
A low refrigerant charge

22. Air filters should be replaced...
Whenever necessary
An uninsulated TXV sensing bulb
A start relay
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

23. A liquid-charged TXV bulb will...
Short cycling and insufficient dehumidification
Technician B
Always have some liquid present in the bulb and diaphragm
An open internal overload protector

24. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
('Y' and 'C') and ('G' and 'C')
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
An undercharge and low ambient conditions

25. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A blown fuse

26. A system that is operating with a clear sight glass shows...
The discharge pressure increases and the amperage increases
The sight glass is full of liquid+the sight glass is full of gas
An increase in suction pressure and an increase in discharge pressure
An undercharge and low ambient conditions

27. What causes the automatic expansion valve to close...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Low superheat
The internal overload is opened
An increase in low-side pressure

28. 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 blown fuse
An uninsulated TXV sensing bulb
Clean the condenser coil
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

29. 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
Technician A
A missing air filter+improper rotation of the indoor blower+blower too small
Short cycling and insufficient dehumidification

30. What are the operating pressures of an oil pressure safety switch...
A start relay
The oil pump pressure and the crankcase pressure
An open internal overload protector
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

31. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
High superheat and low discharge pressure
A start relay
110-120

32. What are three methods for controlling a system's high-side pressure during low ambient conditions...
3 psig
A sensing bulb improperly connected to the suction line
Flooding the condenser - cycling condenser fans - and dampering condenser air
Bad compressor valve

33. 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
Lack of airflow
Low discharge pressure - high suction pressure - and low amp draw
A bad thermostat

34. Which of the following could be the cause for a system's discharge and suction pressure being low...
Current in the compressor circuit
An open internal overload protector
A restricted metering device
Technician A is correct

35. Which of the following is a common cause of an excessively low superheat on a TXV system...
A sensing bulb improperly connected to the suction line
Always have some liquid present in the bulb and diaphragm
Technician B
Technician B

36. 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
Clean the condenser coil
A defective circuit breaker
50-65
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

37. A restricted air filter in an air conditioning system can be identified by...
Run with high head and high suction pressure
Partially frosted evaporator and high superheat
Low superheat
The sensing bulb at a lower temperature than the valve body

38. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Evaporator and compressor
20 to 30
A restricted metering device
The superheat increases and the subcooling decreases

39. A compressor having tight bearings would cause the current value to...
High suction pressure and low superheat
Both technicians are incorrect
Lack of airflow
Rise more than normal

40. 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...
A start capacitor and a solid-state relay
It keeps a constant superheat in the evaporator
An increase in low-side pressure
High superheat and low discharge pressure

41. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A start capacitor and a solid-state relay
A plugged filter drier
The superheat increases and the subcooling decreases
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

42. What is the purpose of an EPR valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
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
Technician B

43. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Evaporator and compressor
Technician B
Low discharge pressure - high suction pressure - and low amp draw
A missing air filter+improper rotation of the indoor blower+blower too small

44. 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
Technician B
A start capacitor and a solid-state relay
An increase of air leakage from ductwork

45. When using a vapor-charged TXV bulb - it is necessary to have...
Partially frosted evaporator and high superheat
The sensing bulb at a lower temperature than the valve body
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B

46. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
The system has been overcharged+The system has air trapped in the condenser
A missing air filter+improper rotation of the indoor blower+blower too small
An uninsulated suction line and a restricted metering device
It would cause the low-side pressure to decrease

47. 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
Contains a solenoid coil and one or more sets of contacts
A start relay

48. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
3 psig
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Dirty condenser - bent condenser fins - and air recirculating over the condenser

49. The temperature range of the suction line from an air conditioning system should be...
Bad compressor valve
50-65
Technician B
3 psig

50. The temperature range of the suction line from an air conditioning system should be...
It would cause the low-side pressure to decrease
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
50-65