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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...
Whenever necessary
Increases starting torque
It is used to control refrigerant pressure in the compressor crankcase
Lack of airflow

2. 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
The sight glass is full of liquid+the sight glass is full of gas
Run with high head and high suction pressure
A defective circuit breaker
A start capacitor and a solid-state relay

3. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
A sensing bulb improperly connected to the suction line
The sight glass is full of liquid+the sight glass is full of gas
An uninsulated suction line and a restricted metering device

4. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An open internal overload protector
'G' to 'C'
50-65

5. The internal overload of an air conditioning compressor senses winding temperature and...
A start relay
It keeps a constant superheat in the evaporator
Current in the compressor circuit
The system has been overcharged+The system has air trapped in the condenser

6. What are the symptoms of a TXV air conditioning system if it has lost its charge...
A bad thermostat
The superheat will increase and the low-side pressure will decrease
A plugged filter drier
Broken rings+broken valves+seized bearings

7. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
Technician A
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The sensing bulb at a lower temperature than the valve body

8. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Condenser fans operating during a low ambient condition and a low suction pressure
An open internal overload protector

9. What is the common cause of a compressor burnout...
Partially frosted evaporator and high superheat
Whenever necessary
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
High suction pressure and low superheat

10. 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
Technician B
A defective circuit breaker
A vacuum test+oil traces around fittings+soap bubble solution

11. 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...
Both technicians are incorrect
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An overcharged system
High superheat and low discharge pressure

12. Superheat is found in an air conditioning system in the...
An increase of air leakage from ductwork
Technician B
It keeps a constant superheat in the evaporator
Evaporator and compressor

13. 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
Always have some liquid present in the bulb and diaphragm
It would cause the low-side pressure to decrease
Technician A is correct
50-65

14. Which of the following will cause excessive discharge pressures on an air conditioning system...
Technician B
The oil pump pressure and the crankcase pressure
Technician A is correct
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

15. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The internal overload is opened
A bad thermostat
The discharge pressure increases and the amperage increases
Low discharge pressure - high suction pressure - and low amp draw

16. A system that uses a thermal electric expansion valve...
Current in the compressor circuit
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An overcharged system
A missing air filter+improper rotation of the indoor blower+blower too small

17. What are two common symptoms of refrigerant leaks in an air conditioning system...
Clean the condenser coil
Run with high head and high suction pressure
Partially frosted evaporator and high superheat
A plugged filter drier

18. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An increase in low-side pressure
('Y' and 'C') and ('G' and 'C')
An uninsulated suction line and a restricted metering device
The superheat increases and the subcooling decreases

19. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The system has been overcharged+The system has air trapped in the condenser
A blown fuse

20. What are the symptoms of an air conditioning system that has a low charge...
An overcharged system
An undercharged system+insufficient airflow over the evaporator coil
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted

21. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
The oil pump pressure and the crankcase pressure
Run with high head and high suction pressure
The sensing bulb at a lower temperature than the valve body

22. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
The system has been overcharged+The system has air trapped in the condenser
Both technicians are correct
20 to 30

23. A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that the outdoor condensing unit is operating - but the indoor blower is not in operation. Technician A says that it is possible that it is a bad fu
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Both technicians are incorrect
'G' to 'C'

24. 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
Broken rings+broken valves+seized bearings
Bad compressor valve
It is used to control refrigerant pressure in the compressor crankcase
Technician B

25. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
50-65
High superheat and low discharge pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

26. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Broken rings+broken valves+seized bearings
An increase in low-side pressure
The superheat increases and the subcooling decreases
The system has been overcharged+The system has air trapped in the condenser

27. What are the symptoms of an air conditioning system that has a low charge...
A restricted metering device
3 psig
An open internal overload protector
The low-side pressure will decrease and the evaporator coil will be partially frosted

28. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Technician B
The external equalizer could be plugged
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Low voltage and a faulty start relay

29. A system that is being serviced has been evacuated down to 500 microns. When the gauges are closed and the vacuum pump is turned off - the pressure starts to increase and stops at 1000 microns. Technician A says that the system has a leak and needs t
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
A low refrigerant charge
Low voltage and a faulty start relay

30. A restricted air filter in an air conditioning system can be identified by...
Low superheat
Whenever necessary
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A defective circuit breaker

31. 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

32. What component is most often the cause of a start capacitor failure...
A start relay
A bad thermostat
A start capacitor and a solid-state relay
Both technicians are correct

33. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
An open internal overload protector
A defective circuit breaker
A start capacitor and a solid-state relay
High suction pressure and low superheat

34. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
A low refrigerant charge
Broken rings+broken valves+seized bearings
3 psig
The low-side pressure will decrease and the evaporator coil will be partially frosted

35. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An increase in low-side pressure
The discharge pressure increases and the amperage increases
Evaporator and compressor
A bad thermostat

36. What component is most often the cause of a start capacitor failure...
Increases starting torque
Lack of airflow
A start relay
An increase in low-side pressure

37. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Low discharge pressure - high suction pressure - and low amp draw
An overcharged system
An increase of air leakage from ductwork
It would cause the low-side pressure to decrease

38. What is the purpose of a CPR valve...
Condenser fans operating during a low ambient condition and a low suction pressure
An acid-core suction line drier
A plugged filter drier
It is used to control refrigerant pressure in the compressor crankcase

39. Which of the following could be the cause for a system's discharge and suction pressure being low...
A start capacitor and a solid-state relay
A restricted metering device
Clean the condenser coil
Lack of airflow

40. What problem or problems can cause low discharge and suction pressure...
A defective circuit breaker
A bad thermostat
Contains a solenoid coil and one or more sets of contacts
An undercharged system+insufficient airflow over the evaporator coil

41. A hard-start kit for an air conditioning system...
Increases starting torque
Flooding the condenser - cycling condenser fans - and dampering condenser air
Broken rings+broken valves+seized bearings
A low refrigerant charge

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
The superheat will increase and the low-side pressure will decrease
An uninsulated suction line and a restricted metering device
Low discharge pressure - high suction pressure - and low amp draw
The external equalizer could be plugged

43. 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 sensing bulb improperly connected to the suction line
Both technicians are correct
Technician B

44. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Low discharge pressure - high suction pressure - and low amp draw
A bad thermostat

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

46. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
Technician B
A start relay
Always have some liquid present in the bulb and diaphragm

47. Which of the following can cause excessive subcooling...
An overcharged system
An acid-core suction line drier
The discharge pressure increases and the amperage increases
Technician B

48. Which of the following is a common cause of an excessively low superheat on a TXV system...
An increase in suction pressure and an increase in discharge pressure
The sensing bulb at a lower temperature than the valve body
A sensing bulb improperly connected to the suction line
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

49. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A bad thermostat
A bad thermostat

50. What is the purpose of the TXV...
An uninsulated TXV sensing bulb
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It keeps a constant superheat in the evaporator
It would cause the low-side pressure to decrease