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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. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician B
Both technicians are incorrect
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

2. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Bad compressor valve
The sensing bulb at a lower temperature than the valve body
An undercharged system+insufficient airflow over the evaporator coil

3. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Flooding the condenser - cycling condenser fans - and dampering condenser air
An undercharged system+insufficient airflow over the evaporator coil
An increase in low-side pressure
Run with high head and high suction pressure

4. 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
A restricted metering device
An undercharged system+insufficient airflow over the evaporator coil
Broken rings+broken valves+seized bearings

5. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An increase of air leakage from ductwork
Technician B
Evaporator and compressor
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

6. 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
Current in the compressor circuit
Condenser fans operating during a low ambient condition and a low suction pressure
('Y' and 'C') and ('G' and 'C')

7. When using a vapor-charged TXV bulb - it is necessary to have...
Whenever necessary
Evaporator and compressor
The sensing bulb at a lower temperature than the valve body
'G' to 'C'

8. Which of the following can cause excessive subcooling...
An overcharged system
An increase of air leakage from ductwork
It is used to control refrigerant pressure in the compressor crankcase
High superheat and low discharge pressure

9. What causes the automatic expansion valve to close...
110-120
Whenever necessary
Bad compressor valve
An increase in low-side pressure

10. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The oil pump pressure and the crankcase pressure
Technician B
Technician A is correct
Low discharge pressure - high suction pressure - and low amp draw

11. A customer calls with an insufficient cooling complaint on a 90
Rise more than normal
The discharge pressure increases and the amperage increases
Technician B
50-65

12. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An uninsulated TXV sensing bulb
An overcharged system
The external equalizer could be plugged
A blown fuse

13. 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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14. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
The oil pump pressure and the crankcase pressure
The internal overload is opened
The system has been overcharged+The system has air trapped in the condenser

15. The temperature range of the suction line from an air conditioning system should be...
Always have some liquid present in the bulb and diaphragm
A dirty condenser - recirculation of condenser air - and a defective condenser fan
50-65
A low refrigerant charge

16. 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...
A plugged filter drier
Short cycling and insufficient dehumidification
Low voltage and a faulty start relay
The superheat increases and the subcooling decreases

17. A system that is operating with a clear sight glass shows...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are incorrect
The sight glass is full of liquid+the sight glass is full of gas
Clean the condenser coil

18. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Low superheat
An increase in low-side pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
Lack of airflow

19. The internal overload of an air conditioning compressor senses winding temperature and...
Low voltage and a faulty start relay
An overcharged system
A low refrigerant charge
Current in the compressor circuit

20. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
Technician B
An uninsulated suction line and a restricted metering device
A vacuum test+oil traces around fittings+soap bubble solution

21. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
Technician B
Technician A
Technician B

22. A split-system air conditioner that uses a piston-type metering device is to be charged with are-22. Technician A says that the outdoor dry-bulb temperature is needed to determine the proper superheat. Technician B says that the indoor wet-bulb tempe
The internal overload is opened
Run with high head and high suction pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Both technicians are correct

23. 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...
A bad thermostat
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Condenser fans operating during a low ambient condition and a low suction pressure

24. What is the purpose of an EPR valve...
A plugged filter drier
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B

25. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A restricted metering device
Bad compressor valve
High superheat and low discharge pressure
Technician B

26. What is the purpose of an EPR valve...
Broken rings+broken valves+seized bearings
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Flooding the condenser - cycling condenser fans - and dampering condenser air
Evaporator and compressor

27. 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
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B

28. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The superheat will increase and the low-side pressure will decrease
The sensing bulb at a lower temperature than the valve body
Technician B
An increase in suction pressure and an increase in discharge pressure

29. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Current in the compressor circuit
A blown fuse
A restricted metering device
The discharge pressure increases and the amperage increases

30. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Rise more than normal
Technician B
Increases starting torque

31. Insufficient airflow can be caused by...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An increase of air leakage from ductwork
A defective circuit breaker

32. What type of problems can be caused by an oversized air conditioning system...
'G' to 'C'
A low refrigerant charge
The external equalizer could be plugged
Short cycling and insufficient dehumidification

33. 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
High suction pressure and low superheat
A start capacitor and a solid-state relay
Technician A
It would cause the low-side pressure to decrease

34. What are the symptoms of a TXV air conditioning system if it has lost its charge...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
'G' to 'C'
A start capacitor and a solid-state relay
The superheat will increase and the low-side pressure will decrease

35. 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...
An overcharged system
Both technicians are incorrect
('Y' and 'C') and ('G' and 'C')
A blown fuse

36. 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
A sensing bulb improperly connected to the suction line
Low voltage and a faulty start relay
Technician B
The discharge pressure increases and the amperage increases

37. What component is most often the cause of a start capacitor failure...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A start relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

38. What is the common cause of a compressor burnout...
'G' to 'C'
It keeps a constant superheat in the evaporator
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A start capacitor and a solid-state relay

39. 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
Clean the condenser coil
Technician B
Evaporator and compressor
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

40. Air filters should be replaced...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A blown fuse
Technician B
Whenever necessary

41. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
The superheat will increase and the low-side pressure will decrease
An open internal overload protector
A plugged filter drier
20 to 30

42. 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
An open internal overload protector
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
('Y' and 'C') and ('G' and 'C')
Flooding the condenser - cycling condenser fans - and dampering condenser air

43. 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 could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Increases starting torque
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

44. A liquid-charged TXV bulb will...
A plugged filter drier
Always have some liquid present in the bulb and diaphragm
The discharge pressure increases and the amperage increases
Low discharge pressure - high suction pressure - and low amp draw

45. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A vacuum test+oil traces around fittings+soap bubble solution
Both technicians are correct
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Run with high head and high suction pressure

46. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A start relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It is used to control refrigerant pressure in the compressor crankcase
It would cause the low-side pressure to decrease

47. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A sensing bulb improperly connected to the suction line
An uninsulated suction line and a restricted metering device
An increase in suction pressure and an increase in discharge pressure
High superheat and low discharge pressure

48. Which of the following will cause excessive discharge pressures on an air conditioning system...
An overcharged system
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
3 psig
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

49. What component is most often the cause of a start capacitor failure...
20 to 30
A start relay
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The system has been overcharged+The system has air trapped in the condenser

50. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Lack of airflow
Technician B