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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. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Technician A is correct
The superheat increases and the subcooling decreases
An undercharge and low ambient conditions
('Y' and 'C') and ('G' and 'C')

2. 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 uninsulated suction line and a restricted metering device
High superheat and low discharge pressure
Broken rings+broken valves+seized bearings
An overcharged system

3. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Lack of airflow
An overcharged system
The discharge pressure increases and the amperage increases
Both technicians are incorrect

4. A compressor having tight bearings would cause the current value to...
Both technicians are correct
Technician B
Lack of airflow
Rise more than normal

5. A liquid-charged TXV bulb will...
Condenser fans operating during a low ambient condition and a low suction pressure
An undercharged system+insufficient airflow over the evaporator coil
Always have some liquid present in the bulb and diaphragm
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

6. The internal overload of an air conditioning compressor senses winding temperature and...
Short cycling and insufficient dehumidification
Current in the compressor circuit
An overcharged system
Technician B

7. What are the symptoms of an air conditioning system that has a low charge...
Partially frosted evaporator and high superheat
An open internal overload protector
('Y' and 'C') and ('G' and 'C')
The low-side pressure will decrease and the evaporator coil will be partially frosted

8. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A bad thermostat
The sight glass is full of liquid+the sight glass is full of gas
Lack of airflow
An uninsulated TXV sensing bulb

9. What component is most often the cause of a start capacitor failure...
An acid-core suction line drier
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Broken rings+broken valves+seized bearings
A start relay

10. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Evaporator and compressor
An uninsulated suction line and a restricted metering device
An open internal overload protector
110-120

11. 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
110-120
A bad thermostat
Technician A is correct

12. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
An overcharged system
High suction pressure and low superheat
The system has been overcharged+The system has air trapped in the condenser
50-65

13. The internal overload of an air conditioning compressor senses winding temperature and...
An overcharged system
Technician B
A restricted metering device
Current in the compressor circuit

14. 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
Clean the condenser coil
The oil pump pressure and the crankcase pressure
Both technicians are correct
An undercharged system+insufficient airflow over the evaporator coil

15. What are two common symptoms of refrigerant leaks in an air conditioning system...
Technician B
Contains a solenoid coil and one or more sets of contacts
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Partially frosted evaporator and high superheat

16. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Technician A
The superheat will increase and the low-side pressure will decrease
The discharge pressure increases and the amperage increases
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

17. What are common methods that are used for leak-testing a system...
The sensing bulb at a lower temperature than the valve body
A vacuum test+oil traces around fittings+soap bubble solution
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The sight glass is full of liquid+the sight glass is full of gas

18. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A defective circuit breaker
High suction pressure and low superheat
Low discharge pressure - high suction pressure - and low amp draw

19. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Whenever necessary
Whenever necessary

20. A hard-start kit consists of...
A start relay
A missing air filter+improper rotation of the indoor blower+blower too small
A start capacitor and a solid-state relay
An increase of air leakage from ductwork

21. 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 sensing bulb improperly connected to the suction line
Condenser fans operating during a low ambient condition and a low suction pressure
High superheat and low discharge pressure
Current in the compressor circuit

22. 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 sight glass is full of liquid+the sight glass is full of gas
Contains a solenoid coil and one or more sets of contacts
Low superheat

23. The temperature range of the suction line from an air conditioning system should be...
Partially frosted evaporator and high superheat
A restricted metering device
The system has been overcharged+The system has air trapped in the condenser
50-65

24. A system that uses a thermal electric expansion valve...
The discharge pressure increases and the amperage increases
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An acid-core suction line drier
Rise more than normal

25. What problem or problems can cause low discharge and suction pressure...
It keeps a constant superheat in the evaporator
Low superheat
A missing air filter+improper rotation of the indoor blower+blower too small
An undercharged system+insufficient airflow over the evaporator coil

26. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Technician A is correct
Broken rings+broken valves+seized bearings
Clean the condenser coil
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

27. A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that the system is using are-22 with the high-side pressure at 290 psig and the low-side pressure at 85 psig. The ambient temperature is 85
Technician A
Technician B
'G' to 'C'
An overcharged system

28. 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
Technician A is correct
Broken rings+broken valves+seized bearings
Technician B
An open internal overload protector

29. A system that uses a thermal electric expansion valve...
The sight glass is full of liquid+the sight glass is full of gas
An open internal overload protector
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Increases starting torque

30. 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 low refrigerant charge
A defective circuit breaker
A missing air filter+improper rotation of the indoor blower+blower too small
A restricted metering device

31. 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
Both technicians are correct
The oil pump pressure and the crankcase pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
An increase in low-side pressure

32. 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
Low discharge pressure - high suction pressure - and low amp draw
Always have some liquid present in the bulb and diaphragm
An overcharged system

33. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A vacuum test+oil traces around fittings+soap bubble solution
Clean the condenser coil
50-65
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

34. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
Technician A is correct
Whenever necessary
Increases starting torque

35. 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
A sensing bulb improperly connected to the suction line
An overcharged system
3 psig

36. What is the purpose of the TXV...
Current in the compressor circuit
The sensing bulb at a lower temperature than the valve body
Lack of airflow
It keeps a constant superheat in the evaporator

37. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
An open internal overload protector
An undercharge and low ambient conditions
20 to 30
A blown fuse

38. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Technician A
Lack of airflow
A defective circuit breaker
An increase in low-side pressure

39. Which of the following is a possible cause for a compressor to overheat...
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A low refrigerant charge
It keeps a constant superheat in the evaporator

40. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Bad compressor valve
Lack of airflow
3 psig
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

41. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Run with high head and high suction pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A vacuum test+oil traces around fittings+soap bubble solution
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

42. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
20 to 30
An uninsulated TXV sensing bulb
A missing air filter+improper rotation of the indoor blower+blower too small

43. Superheat is found in an air conditioning system in the...
High superheat and low discharge pressure
Evaporator and compressor
Broken rings+broken valves+seized bearings
'G' to 'C'

44. 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
Technician B
High superheat and low discharge pressure
Lack of airflow

45. Why is it unsafe to operate an air conditioning system with a low charge...
A low refrigerant charge
Contains a solenoid coil and one or more sets of contacts
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
20 to 30

46. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
An overcharged system
The superheat will increase and the low-side pressure will decrease
Technician B

47. Which of the following can cause excessive subcooling...
An overcharged system
Low superheat
Increases starting torque
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

48. A customer calls with an insufficient cooling complaint on a 90
Lack of airflow
A defective circuit breaker
Technician B
'G' to 'C'

49. What three things can prevent an air conditioning system from releasing heat at the proper rate...
An open internal overload protector
A restricted metering device
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An undercharged system+insufficient airflow over the evaporator coil

50. Which of the following could be the cause for a system's discharge and suction pressure being low...
A blown fuse
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An increase of air leakage from ductwork
A restricted metering device