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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. Air filters should be replaced...
Always have some liquid present in the bulb and diaphragm
Whenever necessary
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

2. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
A restricted metering device
Technician B
Low voltage and a faulty start relay

3. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An overcharged system
The superheat increases and the subcooling decreases
Rise more than normal
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

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
Both technicians are incorrect
Technician A is correct
Short cycling and insufficient dehumidification
A start capacitor and a solid-state relay

5. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The superheat will increase and the low-side pressure will decrease
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan

6. 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...
An increase in suction pressure and an increase in discharge pressure
A defective circuit breaker
The external equalizer could be plugged
The internal overload is opened

7. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
('Y' and 'C') and ('G' and 'C')
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

8. What are two common symptoms of refrigerant leaks in an air conditioning system...
Bad compressor valve
Broken rings+broken valves+seized bearings
An uninsulated suction line and a restricted metering device
Partially frosted evaporator and high superheat

9. 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
110-120
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A start relay

10. What is the purpose of a CPR valve...
A defective circuit breaker
20 to 30
'G' to 'C'
It is used to control refrigerant pressure in the compressor crankcase

11. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A plugged filter drier
Increases starting torque
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

12. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
High superheat and low discharge pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Always have some liquid present in the bulb and diaphragm
An increase in low-side pressure

13. 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
Whenever necessary
Broken rings+broken valves+seized bearings
Technician A is correct
Technician B

14. 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...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B
Technician B
The internal overload is opened

15. 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 increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Contains a solenoid coil and one or more sets of contacts
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An overcharged system

16. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
Both technicians are correct
Technician B
20 to 30

17. 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...
The superheat will increase and the low-side pressure will decrease
Condenser fans operating during a low ambient condition and a low suction pressure
An uninsulated TXV sensing bulb
Low discharge pressure - high suction pressure - and low amp draw

18. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A blown fuse
Run with high head and high suction pressure
The sensing bulb at a lower temperature than the valve body

19. What is the purpose of an EPR valve...
An increase in suction pressure and an increase in discharge pressure
An uninsulated suction line and a restricted metering device
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

20. Which of the following could be the cause for a system's discharge and suction pressure being low...
Rise more than normal
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A restricted metering device
The oil pump pressure and the crankcase pressure

21. 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...
A blown fuse
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician A
An uninsulated TXV sensing bulb

22. What are three methods for controlling a system's high-side pressure during low ambient conditions...
20 to 30
Increases starting torque
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Flooding the condenser - cycling condenser fans - and dampering condenser air

23. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Clean the condenser coil
It would cause the low-side pressure to decrease
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

24. What is the purpose of the TXV...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It keeps a constant superheat in the evaporator

25. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
It would cause the low-side pressure to decrease
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An undercharged system+insufficient airflow over the evaporator coil
High suction pressure and low superheat

26. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
An acid-core suction line drier

27. What component is most often the cause of a start capacitor failure...
Broken rings+broken valves+seized bearings
A start relay
The discharge pressure increases and the amperage increases
Technician B

28. 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
Contains a solenoid coil and one or more sets of contacts
Short cycling and insufficient dehumidification
A defective circuit breaker
A low refrigerant charge

29. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Evaporator and compressor
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The superheat will increase and the low-side pressure will decrease
The system has been overcharged+The system has air trapped in the condenser

30. What are the operating pressures of an oil pressure safety switch...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
It keeps a constant superheat in the evaporator
The oil pump pressure and the crankcase pressure
A blown fuse

31. 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
50-65
High suction pressure and low superheat
A restricted metering device
Technician B

32. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The sensing bulb at a lower temperature than the valve body
20 to 30
An overcharged system
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 B
Contains a solenoid coil and one or more sets of contacts
A missing air filter+improper rotation of the indoor blower+blower too small
Technician A is correct

34. The internal overload of an air conditioning compressor senses winding temperature and...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
Current in the compressor circuit
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

35. Superheat is found in an air conditioning system in the...
The superheat will increase and the low-side pressure will decrease
A plugged filter drier
50-65
Evaporator and compressor

36. What problem or problems can cause low discharge and suction pressure...
The sensing bulb at a lower temperature than the valve body
Technician B
A restricted metering device
An undercharged system+insufficient airflow over the evaporator coil

37. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Low discharge pressure - high suction pressure - and low amp draw
High suction pressure and low superheat
The system has been overcharged+The system has air trapped in the condenser

38. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

39. What are two common symptoms of refrigerant leaks in an air conditioning system...
('Y' and 'C') and ('G' and 'C')
The sight glass is full of liquid+the sight glass is full of gas
Partially frosted evaporator and high superheat
Whenever necessary

40. What are the symptoms of an air conditioning system that has a low charge...
High superheat and low discharge pressure
Technician A
'G' to 'C'
The low-side pressure will decrease and the evaporator coil will be partially frosted

41. A system that uses a thermal electric expansion valve...
An overcharged system
An open internal overload protector
Low superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

42. 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
The superheat increases and the subcooling decreases
An uninsulated suction line and a restricted metering device
A start capacitor and a solid-state relay

43. The internal overload of an air conditioning compressor senses winding temperature and...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The superheat will increase and the low-side pressure will decrease
Current in the compressor circuit
The discharge pressure increases and the amperage increases

44. A restricted air filter in an air conditioning system can be identified by...
Partially frosted evaporator and high superheat
An increase in suction pressure and an increase in discharge pressure
Low superheat
Technician B

45. 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
Contains a solenoid coil and one or more sets of contacts
Technician B
Rise more than normal
Both technicians are correct

46. What component is most often the cause of a start capacitor failure...
A start relay
20 to 30
Short cycling and insufficient dehumidification
Condenser fans operating during a low ambient condition and a low suction pressure

47. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A restricted metering device
110-120
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
3 psig

48. 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

49. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
An open internal overload protector
Run with high head and high suction pressure
An undercharged system+insufficient airflow over the evaporator coil
Technician B

50. What are common methods that are used for leak-testing a system...
A bad thermostat
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
An acid-core suction line drier