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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. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
An undercharge and low ambient conditions
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The external equalizer could be plugged
A plugged filter drier

2. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An undercharge and low ambient conditions
Evaporator and compressor

3. Which of the following can cause excessive subcooling...
The superheat increases and the subcooling decreases
Rise more than normal
An overcharged system
Both technicians are correct

4. 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
('Y' and 'C') and ('G' and 'C')
Both technicians are incorrect
An overcharged system
Technician A is correct

5. 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 system has been overcharged+The system has air trapped in the condenser
High suction pressure and low superheat
20 to 30

6. Which of the following will cause excessive discharge pressures on an air conditioning system...
An uninsulated suction line and a restricted metering device
Bad compressor valve
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
'G' to 'C'

7. 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
Condenser fans operating during a low ambient condition and a low suction pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The superheat will increase and the low-side pressure will decrease
Both technicians are correct

8. What type of problems can be caused by an oversized air conditioning system...
An increase of air leakage from ductwork
Technician B
High suction pressure and low superheat
Short cycling and insufficient dehumidification

9. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
An overcharged system
Evaporator and compressor
A start capacitor and a solid-state relay

10. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
A vacuum test+oil traces around fittings+soap bubble solution
The sensing bulb at a lower temperature than the valve body
Always have some liquid present in the bulb and diaphragm

11. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B
Technician A

12. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Technician B
('Y' and 'C') and ('G' and 'C')
The low-side pressure will decrease and the evaporator coil will be partially frosted
A missing air filter+improper rotation of the indoor blower+blower too small

13. 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
It keeps a constant superheat in the evaporator
A vacuum test+oil traces around fittings+soap bubble solution
A defective circuit breaker
Technician B

14. Which of the following can cause excessive subcooling...
A defective circuit breaker
Condenser fans operating during a low ambient condition and a low suction pressure
A plugged filter drier
An overcharged system

15. A system that is operating with a clear sight glass shows...
Low voltage and a faulty start relay
A bad thermostat
The sight glass is full of liquid+the sight glass is full of gas
An undercharged system+insufficient airflow over the evaporator coil

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...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
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
An overcharged system

17. What are the symptoms of an air conditioning system that has a low charge...
The internal overload is opened
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
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

18. The internal overload of an air conditioning compressor senses winding temperature and...
Technician B
Current in the compressor circuit
The superheat increases and the subcooling decreases
20 to 30

19. 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...
Technician B
'G' to 'C'
('Y' and 'C') and ('G' and 'C')
The sensing bulb at a lower temperature than the valve body

20. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Condenser fans operating during a low ambient condition and a low suction pressure
Bad compressor valve
Short cycling and insufficient dehumidification
Technician B

21. 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
Low discharge pressure - high suction pressure - and low amp draw
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
3 psig

22. 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
50-65
Both technicians are correct
('Y' and 'C') and ('G' and 'C')

23. What are common methods that are used for leak-testing a system...
A low refrigerant charge
A plugged filter drier
A vacuum test+oil traces around fittings+soap bubble solution
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

24. 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
50-65
Contains a solenoid coil and one or more sets of contacts
The external equalizer could be plugged
The low-side pressure will decrease and the evaporator coil will be partially frosted

25. A hard-start kit for an air conditioning system...
Increases starting torque
Evaporator and compressor
Flooding the condenser - cycling condenser fans - and dampering condenser air
A missing air filter+improper rotation of the indoor blower+blower too small

26. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Low superheat
Run with high head and high suction pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A restricted metering device

27. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Low superheat
An increase in low-side pressure
A low refrigerant charge
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

28. What is the purpose of a CPR valve...
An undercharge and low ambient conditions
It is used to control refrigerant pressure in the compressor crankcase
A vacuum test+oil traces around fittings+soap bubble solution
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

29. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Technician A is correct
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Current in the compressor circuit

30. 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
A start relay
It is used to control refrigerant pressure in the compressor crankcase
Technician B
High suction pressure and low superheat

31. 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 dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
High superheat and low discharge pressure
Run with high head and high suction pressure
It is used to control refrigerant pressure in the compressor crankcase

32. 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
It keeps a constant superheat in the evaporator
A plugged filter drier
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

33. Which of the following could be the cause for a system's discharge and suction pressure being low...
It keeps a constant superheat in the evaporator
A restricted metering device
An increase in low-side pressure
Technician B

34. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Low superheat
A defective circuit breaker
'G' to 'C'

35. A customer calls with an insufficient cooling complaint on a 90
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An acid-core suction line drier

36. Which of the following will cause excessive discharge pressures on an air conditioning system...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
It is used to control refrigerant pressure in the compressor crankcase
A sensing bulb improperly connected to the suction line

37. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
It would cause the low-side pressure to decrease
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B

38. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician A is correct
A blown fuse

39. 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...
High superheat and low discharge pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The external equalizer could be plugged
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

40. Air filters should be replaced...
High suction pressure and low superheat
Whenever necessary
Evaporator and compressor
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

41. 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
It would cause the low-side pressure to decrease
Both technicians are correct
An open internal overload protector
Both technicians are incorrect

42. 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
The internal overload is opened
Technician B
An acid-core suction line drier

43. 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
A blown fuse
Technician B
Technician B

44. A commercial customer calls on a 90
An increase of air leakage from ductwork
The system has been overcharged+The system has air trapped in the condenser
Low superheat
A low refrigerant charge

45. A customer calls with an insufficient cooling complaint on a 90
An uninsulated suction line and a restricted metering device
Rise more than normal
Technician A is correct
Technician B

46. 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
Whenever necessary
An undercharged system+insufficient airflow over the evaporator coil
'G' to 'C'
Both technicians are incorrect

47. Insufficient airflow can be caused by...
An overcharged system
A start relay
An increase of air leakage from ductwork
A sensing bulb improperly connected to the suction line

48. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Low superheat
('Y' and 'C') and ('G' and 'C')

49. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The superheat increases and the subcooling decreases
Low discharge pressure - high suction pressure - and low amp draw
110-120
20 to 30

50. What component is most often the cause of a start capacitor failure...
A start relay
An open internal overload protector
Technician B
3 psig

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