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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. 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...
The internal overload is opened
The oil pump pressure and the crankcase pressure
The system has been overcharged+The system has air trapped in the condenser
Whenever necessary

2. 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
A start relay
An acid-core suction line drier
Broken rings+broken valves+seized bearings
Flooding the condenser - cycling condenser fans - and dampering condenser air

3. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A bad thermostat
20 to 30
An overcharged system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

4. 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
Both technicians are incorrect
It is used to control refrigerant pressure in the compressor crankcase
Flooding the condenser - cycling condenser fans - and dampering condenser air
An open internal overload protector

5. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
20 to 30
'G' to 'C'
Low discharge pressure - high suction pressure - and low amp draw
It would cause the low-side pressure to decrease

6. 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
Condenser fans operating during a low ambient condition and a low suction pressure
A defective circuit breaker
Technician B
High suction pressure and low superheat

7. A liquid-charged TXV bulb will...
Technician B
Always have some liquid present in the bulb and diaphragm
A low refrigerant charge
Technician B

8. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Technician A
Flooding the condenser - cycling condenser fans - and dampering condenser air
Broken rings+broken valves+seized bearings
20 to 30

9. 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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10. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Bad compressor valve
Low discharge pressure - high suction pressure - and low amp draw

11. 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
The oil pump pressure and the crankcase pressure
Technician A is correct
A low refrigerant charge
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

12. What causes the automatic expansion valve to close...
An increase in low-side pressure
The sight glass is full of liquid+the sight glass is full of gas
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small

13. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A low refrigerant charge
It is used to control refrigerant pressure in the compressor crankcase
Bad compressor valve
Lack of airflow

14. 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
'G' to 'C'
A vacuum test+oil traces around fittings+soap bubble solution
Clean the condenser coil
An open internal overload protector

15. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Evaporator and compressor
An uninsulated suction line and a restricted metering device

16. A system that uses a thermal electric expansion valve...
The internal overload is opened
Increases starting torque
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A sensing bulb improperly connected to the suction line

17. What is the purpose of a CPR valve...
An undercharged system+insufficient airflow over the evaporator coil
It is used to control refrigerant pressure in the compressor crankcase
An acid-core suction line drier
Technician B

18. 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
Technician B
Low voltage and a faulty start relay
High superheat and low discharge pressure
A restricted metering device

19. 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
A plugged filter drier
Broken rings+broken valves+seized bearings
('Y' and 'C') and ('G' and 'C')
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

20. 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...
Technician A is correct
High superheat and low discharge pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Current in the compressor circuit

21. What component is most often the cause of a start capacitor failure...
An undercharge and low ambient conditions
High suction pressure and low superheat
A start relay
Technician B

22. A system that is operating with a clear sight glass shows...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are incorrect
The sight glass is full of liquid+the sight glass is full of gas
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

23. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The sensing bulb at a lower temperature than the valve body
Contains a solenoid coil and one or more sets of contacts
Low discharge pressure - high suction pressure - and low amp draw
An open internal overload protector

24. Which of the following could be the cause for a system's discharge and suction pressure being low...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A plugged filter drier
A restricted metering device

25. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Technician B
Both technicians are incorrect
The discharge pressure increases and the amperage increases
Technician B

26. Which of the following will cause excessive discharge pressures on an air conditioning system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The oil pump pressure and the crankcase pressure
The external equalizer could be plugged
A vacuum test+oil traces around fittings+soap bubble solution

27. Insufficient airflow can be caused by...
Lack of airflow
Rise more than normal
An increase of air leakage from ductwork
The sight glass is full of liquid+the sight glass is full of gas

28. 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
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure
A start capacitor and a solid-state relay

29. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Broken rings+broken valves+seized bearings
Technician B
3 psig
A sensing bulb improperly connected to the suction line

30. The internal overload of an air conditioning compressor senses winding temperature and...
The system has been overcharged+The system has air trapped in the condenser
Broken rings+broken valves+seized bearings
Current in the compressor circuit
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

31. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An uninsulated suction line and a restricted metering device
Flooding the condenser - cycling condenser fans - and dampering condenser air
20 to 30

32. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Technician B
The sight glass is full of liquid+the sight glass is full of gas
High suction pressure and low superheat
Short cycling and insufficient dehumidification

33. 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
An increase in suction pressure and an increase in discharge pressure
High superheat and low discharge pressure
A sensing bulb improperly connected to the suction line
Clean the condenser coil

34. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
20 to 30
The discharge pressure increases and the amperage increases
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The external equalizer could be plugged

35. A system that is operating with a clear sight glass shows...
Clean the condenser coil
The sight glass is full of liquid+the sight glass is full of gas
An overcharged system
The external equalizer could be plugged

36. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
An undercharge and low ambient conditions
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A low refrigerant charge

37. 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
The superheat will increase and the low-side pressure will decrease
Lack of airflow
Technician B
High superheat and low discharge pressure

38. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
An acid-core suction line drier
Lack of airflow
An increase of air leakage from ductwork
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

39. A compressor having tight bearings would cause the current value to...
A sensing bulb improperly connected to the suction line
It is used to control refrigerant pressure in the compressor crankcase
Rise more than normal
Run with high head and high suction pressure

40. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
Increases starting torque
Low discharge pressure - high suction pressure - and low amp draw
Technician A

41. Insufficient airflow can be caused by...
A bad thermostat
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An increase of air leakage from ductwork
50-65

42. 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
Lack of airflow
The external equalizer could be plugged
Current in the compressor circuit
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

43. The best description of a relay would be...
Short cycling and insufficient dehumidification
Technician B
Technician A
Contains a solenoid coil and one or more sets of contacts

44. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An overcharged system
An increase of air leakage from ductwork
Partially frosted evaporator and high superheat

45. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
('Y' and 'C') and ('G' and 'C')

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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A vacuum test+oil traces around fittings+soap bubble solution
Rise more than normal
Technician B

47. The temperature range of the suction line from an air conditioning system should be...
50-65
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Always have some liquid present in the bulb and diaphragm
The oil pump pressure and the crankcase pressure

48. A customer calls and says that her air conditioning system is not cooling properly. Upon arrival - a technician notices that the suction line and compressor have frost buildup. Technician A says that the problem is probably a low charge. Technician B
The sensing bulb at a lower temperature than the valve body
Technician B
The superheat increases and the subcooling decreases
An uninsulated TXV sensing bulb

49. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The discharge pressure increases and the amperage increases
High suction pressure and low superheat
Whenever necessary

50. When using a vapor-charged TXV bulb - it is necessary to have...
The sight glass is full of liquid+the sight glass is full of gas
An overcharged system
('Y' and 'C') and ('G' and 'C')
The sensing bulb at a lower temperature than the valve body