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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 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 superheat increases and the subcooling decreases
An undercharge and low ambient conditions
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B

2. A liquid-charged TXV bulb will...
Technician B
High suction pressure and low superheat
Always have some liquid present in the bulb and diaphragm
An open internal overload protector

3. 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
An increase in low-side pressure
The oil pump pressure and the crankcase pressure
Technician A is correct
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

4. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It would cause the low-side pressure to decrease
An uninsulated suction line and a restricted metering device
Technician B
Low superheat

5. 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 blown fuse
A bad thermostat
Partially frosted evaporator and high superheat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

6. 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
Low voltage and a faulty start relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

7. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
('Y' and 'C') and ('G' and 'C')
A bad thermostat
Low voltage and a faulty start relay

8. 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
A plugged filter drier
Whenever necessary
3 psig

9. 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
Clean the condenser coil
A start relay
It is used to control refrigerant pressure in the compressor crankcase

10. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A start capacitor and a solid-state relay
Whenever necessary
A missing air filter+improper rotation of the indoor blower+blower too small
The system has been overcharged+The system has air trapped in the condenser

11. A restricted air filter in an air conditioning system can be identified by...
The superheat will increase and the low-side pressure will decrease
Broken rings+broken valves+seized bearings
Flooding the condenser - cycling condenser fans - and dampering condenser air
Low superheat

12. What are two common symptoms of refrigerant leaks in an air conditioning system...
A defective circuit breaker
It would cause the low-side pressure to decrease
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Partially frosted evaporator and high superheat

13. What are the operating pressures of an oil pressure safety switch...
A start capacitor and a solid-state relay
The oil pump pressure and the crankcase pressure
An open internal overload protector
High superheat and low discharge pressure

14. 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
Clean the condenser coil
A start capacitor and a solid-state relay
Technician B
('Y' and 'C') and ('G' and 'C')

15. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
High superheat and low discharge pressure
Technician B
Lack of airflow
Partially frosted evaporator and high superheat

16. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
The sight glass is full of liquid+the sight glass is full of gas
A start relay
An open internal overload protector

17. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A plugged filter drier
Run with high head and high suction pressure
The superheat will increase and the low-side pressure will decrease
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

18. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
20 to 30
It would cause the low-side pressure to decrease

19. Which of the following could be the cause for a system's discharge and suction pressure being low...
An undercharge and low ambient conditions
Low discharge pressure - high suction pressure - and low amp draw
A restricted metering device
A start relay

20. The internal overload of an air conditioning compressor senses winding temperature and...
Run with high head and high suction pressure
Broken rings+broken valves+seized bearings
Current in the compressor circuit
A low refrigerant charge

21. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
The superheat increases and the subcooling decreases
'G' to 'C'
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

22. 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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23. A hard-start kit consists of...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A start relay
Broken rings+broken valves+seized bearings
A start capacitor and a solid-state relay

24. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
A defective circuit breaker
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The sight glass is full of liquid+the sight glass is full of gas

25. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An undercharged system+insufficient airflow over the evaporator coil
The discharge pressure increases and the amperage increases
An undercharge and low ambient conditions
Current in the compressor circuit

26. Air filters should be replaced...
Condenser fans operating during a low ambient condition and a low suction pressure
20 to 30
Technician B
Whenever necessary

27. What problem or problems can cause low discharge and suction pressure...
Flooding the condenser - cycling condenser fans - and dampering condenser air
An undercharged system+insufficient airflow over the evaporator coil
Low voltage and a faulty start relay
Evaporator and compressor

28. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A defective circuit breaker
The superheat will increase and the low-side pressure will decrease
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

29. 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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30. 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
It is used to control refrigerant pressure in the compressor crankcase
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An increase in suction pressure and an increase in discharge pressure

31. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Run with high head and high suction pressure
Technician B
Technician A is correct

32. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
Condenser fans operating during a low ambient condition and a low suction pressure
An increase of air leakage from ductwork
An acid-core suction line drier

33. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
20 to 30
Low discharge pressure - high suction pressure - and low amp draw
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

34. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
It is used to control refrigerant pressure in the compressor crankcase
Evaporator and compressor
Technician B

35. What are the symptoms of an air conditioning system that has a low charge...
An open internal overload protector
Evaporator and compressor
Low voltage and a faulty start relay
The low-side pressure will decrease and the evaporator coil will be partially frosted

36. Superheat is found in an air conditioning system in the...
Evaporator and compressor
An open internal overload protector
Current in the compressor circuit
It keeps a constant superheat in the evaporator

37. 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
An increase in low-side pressure
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

38. What is the purpose of an EPR valve...
An increase in low-side pressure
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
Technician B

39. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
An increase in low-side pressure
Low superheat
A blown fuse

40. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
110-120
A dirty condenser - recirculation of condenser air - and a defective condenser fan
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

41. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Run with high head and high suction pressure
Technician B

42. A system that is operating with a clear sight glass shows...
A sensing bulb improperly connected to the suction line
The sight glass is full of liquid+the sight glass is full of gas
Partially frosted evaporator and high superheat
A plugged filter drier

43. 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
The superheat increases and the subcooling decreases
The superheat will increase and the low-side pressure will decrease
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

44. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The superheat will increase and the low-side pressure will decrease
It keeps a constant superheat in the evaporator
The system has been overcharged+The system has air trapped in the condenser
The superheat increases and the subcooling decreases

45. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A blown fuse
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Always have some liquid present in the bulb and diaphragm
Technician B

46. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are incorrect
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
3 psig

47. 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
A defective circuit breaker
Current in the compressor circuit
Low discharge pressure - high suction pressure - and low amp draw
('Y' and 'C') and ('G' and 'C')

48. A restricted air filter in an air conditioning system can be identified by...
An undercharge and low ambient conditions
Technician B
Low superheat
Run with high head and high suction pressure

49. 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
Technician B
Clean the condenser coil
An overcharged system
A defective circuit breaker

50. Which of the following is a common cause of an excessively low superheat on a TXV system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A sensing bulb improperly connected to the suction line
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The system has been overcharged+The system has air trapped in the condenser