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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 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Evaporator and compressor

2. Which of the following can cause low superheat in a TXV system...
An uninsulated suction line and a restricted metering device
The oil pump pressure and the crankcase pressure
An uninsulated TXV sensing bulb
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

3. A hard-start kit for an air conditioning system...
Both technicians are correct
3 psig
Increases starting torque
Technician B

4. What is the purpose of the TXV...
A defective circuit breaker
The sensing bulb at a lower temperature than the valve body
It keeps a constant superheat in the evaporator
Technician A is correct

5. A hard-start kit consists of...
Increases starting torque
A start capacitor and a solid-state relay
Rise more than normal
It is used to control refrigerant pressure in the compressor crankcase

6. 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 external equalizer could be plugged
The superheat will increase and the low-side pressure will decrease
50-65
3 psig

7. 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...
An overcharged system
Increases starting torque
High superheat and low discharge pressure
Technician B

8. Superheat is found in an air conditioning system in the...
Technician A
An uninsulated suction line and a restricted metering device
Evaporator and compressor
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

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
3 psig
An open internal overload protector
Technician B
An increase in low-side pressure

10. When using a vapor-charged TXV bulb - it is necessary to have...
Both technicians are correct
The sight glass is full of liquid+the sight glass is full of gas
The sensing bulb at a lower temperature than the valve body
It keeps a constant superheat in the evaporator

11. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Clean the condenser coil
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small

12. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
Technician A
An uninsulated suction line and a restricted metering device
It is used to control refrigerant pressure in the compressor crankcase

13. What are the symptoms of an air conditioning system that has a low charge...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
Increases starting torque

14. Which of the following is a common cause of an excessively low superheat on a TXV system...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A sensing bulb improperly connected to the suction line
Run with high head and high suction pressure
An acid-core suction line drier

15. What are common methods that are used for leak-testing a system...
An overcharged system
110-120
Always have some liquid present in the bulb and diaphragm
A vacuum test+oil traces around fittings+soap bubble solution

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...
Broken rings+broken valves+seized bearings
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Condenser fans operating during a low ambient condition and a low suction pressure
Partially frosted evaporator and high superheat

17. 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...
Low voltage and a faulty start relay
A defective circuit breaker
The internal overload is opened
Flooding the condenser - cycling condenser fans - and dampering condenser air

18. The temperature range of the suction line from an air conditioning system should be...
A plugged filter drier
50-65
Always have some liquid present in the bulb and diaphragm
A missing air filter+improper rotation of the indoor blower+blower too small

19. What three things can prevent an air conditioning system from releasing heat at the proper rate...
'G' to 'C'
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B

20. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
Lack of airflow
Contains a solenoid coil and one or more sets of contacts
A low refrigerant charge

21. Air filters should be replaced...
Both technicians are incorrect
The sensing bulb at a lower temperature than the valve body
A vacuum test+oil traces around fittings+soap bubble solution
Whenever necessary

22. 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
Technician A is correct
Both technicians are correct
Low discharge pressure - high suction pressure - and low amp draw

23. 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
Broken rings+broken valves+seized bearings
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Both technicians are incorrect
Partially frosted evaporator and high superheat

24. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Technician A
Technician B
Run with high head and high suction pressure
An uninsulated suction line and a restricted metering device

25. Air filters should be replaced...
The external equalizer could be plugged
Whenever necessary
The low-side pressure will decrease and the evaporator coil will be partially frosted
50-65

26. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
Technician B
High suction pressure and low superheat
Run with high head and high suction pressure

27. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician A
A vacuum test+oil traces around fittings+soap bubble solution
An increase in suction pressure and an increase in discharge pressure

28. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
Flooding the condenser - cycling condenser fans - and dampering condenser air
An overcharged system
A low refrigerant charge

29. A commercial customer calls on a 90
Partially frosted evaporator and high superheat
Contains a solenoid coil and one or more sets of contacts
Both technicians are incorrect
The system has been overcharged+The system has air trapped in the condenser

30. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The sight glass is full of liquid+the sight glass is full of gas
Broken rings+broken valves+seized bearings
A plugged filter drier
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

31. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Short cycling and insufficient dehumidification
Current in the compressor circuit

32. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An undercharge and low ambient conditions
An uninsulated TXV sensing bulb
The discharge pressure increases and the amperage increases
Current in the compressor circuit

33. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Whenever necessary
110-120
The sensing bulb at a lower temperature than the valve body
Low superheat

34. What problem or problems can cause low discharge and suction pressure...
The superheat will increase and the low-side pressure will decrease
An undercharged system+insufficient airflow over the evaporator coil
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The oil pump pressure and the crankcase pressure

35. The best description of a relay would be...
A blown fuse
An undercharge and low ambient conditions
A low refrigerant charge
Contains a solenoid coil and one or more sets of contacts

36. What are common methods that are used for leak-testing a system...
Lack of airflow
Both technicians are correct
An uninsulated suction line and a restricted metering device
A vacuum test+oil traces around fittings+soap bubble solution

37. Which of the following can cause excessive subcooling...
Increases starting torque
High superheat and low discharge pressure
An overcharged system
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

38. What are two problems that can cause an air conditioning system to have an excessively high superheat...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A vacuum test+oil traces around fittings+soap bubble solution
An uninsulated suction line and a restricted metering device

39. A restricted air filter in an air conditioning system can be identified by...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Low superheat
Evaporator and compressor
An undercharge and low ambient conditions

40. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The system has been overcharged+The system has air trapped in the condenser
Increases starting torque

41. What problem or problems can cause low discharge and suction pressure...
Technician B
An undercharged system+insufficient airflow over the evaporator coil
The sight glass is full of liquid+the sight glass is full of gas
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

42. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
Condenser fans operating during a low ambient condition and a low suction pressure
Partially frosted evaporator and high superheat
Rise more than normal

43. A system that is operating with a clear sight glass shows...
A blown fuse
The sight glass is full of liquid+the sight glass is full of gas
3 psig
Technician A is correct

44. 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 thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
High superheat and low discharge pressure
Broken rings+broken valves+seized bearings
50-65

45. 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
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
Rise more than normal

46. 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
High superheat and low discharge pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician A is correct

47. 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
The sight glass is full of liquid+the sight glass is full of gas
An open internal overload protector
Flooding the condenser - cycling condenser fans - and dampering condenser air

48. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
A restricted metering device
50-65
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An acid-core suction line drier

49. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A vacuum test+oil traces around fittings+soap bubble solution
A bad thermostat
20 to 30
Flooding the condenser - cycling condenser fans - and dampering condenser air

50. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
The sight glass is full of liquid+the sight glass is full of gas
Contains a solenoid coil and one or more sets of contacts
Increases starting torque