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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. What component is most often the cause of a start capacitor failure...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An uninsulated suction line and a restricted metering device
A start relay
The oil pump pressure and the crankcase pressure

2. A liquid-charged TXV bulb will...
'G' to 'C'
An uninsulated suction line and a restricted metering device
Always have some liquid present in the bulb and diaphragm
Run with high head and high suction pressure

3. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The oil pump pressure and the crankcase pressure
Contains a solenoid coil and one or more sets of contacts
A bad thermostat

4. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A plugged filter drier
Technician B
20 to 30
The superheat increases and the subcooling decreases

5. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
An acid-core suction line drier
Both technicians are incorrect
The superheat will increase and the low-side pressure will decrease

6. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Technician B
An undercharge and low ambient conditions
50-65
A defective circuit breaker

7. Why is it unsafe to operate an air conditioning system with a low charge...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Increases starting torque
An undercharged system+insufficient airflow over the evaporator coil

8. A system that is operating with a clear sight glass shows...
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
A start relay
The sight glass is full of liquid+the sight glass is full of gas

9. What type of problems can be caused by an oversized air conditioning system...
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Both technicians are incorrect
Short cycling and insufficient dehumidification

10. 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...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
'G' to 'C'
An uninsulated TXV sensing bulb
Low voltage and a faulty start relay

11. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Both technicians are correct
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An increase of air leakage from ductwork
An overcharged system

12. Which of the following can cause excessive subcooling...
An overcharged system
A sensing bulb improperly connected to the suction line
An open internal overload protector
Both technicians are correct

13. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
The system has been overcharged+The system has air trapped in the condenser
Lack of airflow
An overcharged system
Bad compressor valve

14. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated suction line and a restricted metering device
An open internal overload protector
High superheat and low discharge pressure
Rise more than normal

15. A hard-start kit for an air conditioning system...
Increases starting torque
20 to 30
20 to 30
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

16. The best description of a relay would be...
Condenser fans operating during a low ambient condition and a low suction pressure
The sensing bulb at a lower temperature than the valve body
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Contains a solenoid coil and one or more sets of contacts

17. 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
A low refrigerant charge
110-120
Evaporator and compressor
Technician B

18. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
20 to 30
Whenever necessary
An acid-core suction line drier
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

19. 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...
High superheat and low discharge pressure
Broken rings+broken valves+seized bearings
Partially frosted evaporator and high superheat
Whenever necessary

20. 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...
Technician B
A start relay
The internal overload is opened
Technician B

21. 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 can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Flooding the condenser - cycling condenser fans - and dampering condenser air
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

22. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Current in the compressor circuit
Contains a solenoid coil and one or more sets of contacts
An undercharged system+insufficient airflow over the evaporator coil
A missing air filter+improper rotation of the indoor blower+blower too small

23. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Rise more than normal
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
An undercharged system+insufficient airflow over the evaporator coil

24. A customer calls with an insufficient cooling complaint on a 90
'G' to 'C'
Current in the compressor circuit
An increase in suction pressure and an increase in discharge pressure
Technician B

25. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
3 psig
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician A
High superheat and low discharge pressure

26. Air filters should be replaced...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Whenever necessary
A plugged filter drier
Technician A

27. 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
A low refrigerant charge
The sight glass is full of liquid+the sight glass is full of gas
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

28. Which of the following is a possible cause for a compressor to overheat...
An undercharged system+insufficient airflow over the evaporator coil
The system has been overcharged+The system has air trapped in the condenser
A low refrigerant charge
High suction pressure and low superheat

29. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
A plugged filter drier
It is used to control refrigerant pressure in the compressor crankcase
50-65

30. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The superheat will increase and the low-side pressure will decrease
An uninsulated suction line and a restricted metering device

31. 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
High superheat and low discharge pressure
An overcharged system
A low refrigerant charge

32. Which of the following will cause excessive discharge pressures on an air conditioning system...
It keeps a constant superheat in the evaporator
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
50-65

33. A hard-start kit consists of...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A start capacitor and a solid-state relay
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An increase in suction pressure and an increase in discharge pressure

34. What are common methods that are used for leak-testing a system...
A bad thermostat
A vacuum test+oil traces around fittings+soap bubble solution
Increases starting torque
Both technicians are incorrect

35. 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
Low voltage and a faulty start relay
A defective circuit breaker
Low discharge pressure - high suction pressure - and low amp draw

36. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Current in the compressor circuit

37. 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
A sensing bulb improperly connected to the suction line
High superheat and low discharge pressure
A missing air filter+improper rotation of the indoor blower+blower too small
Technician A

38. What causes the automatic expansion valve to close...
An increase in low-side pressure
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
A start relay

39. 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
The system has been overcharged+The system has air trapped in the condenser
An increase in low-side pressure
An increase of air leakage from ductwork
Both technicians are correct

40. What type of problems can be caused by an oversized air conditioning system...
Rise more than normal
'G' to 'C'
Short cycling and insufficient dehumidification
A dirty condenser - recirculation of condenser air - and a defective condenser fan

41. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
20 to 30
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

42. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
20 to 30
20 to 30
A missing air filter+improper rotation of the indoor blower+blower too small

43. 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
Low discharge pressure - high suction pressure - and low amp draw
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The internal overload is opened
The external equalizer could be plugged

44. A hard-start kit for an air conditioning system...
Partially frosted evaporator and high superheat
It would cause the low-side pressure to decrease
An undercharge and low ambient conditions
Increases starting torque

45. Which of the following could be the cause for a system's discharge and suction pressure being low...
50-65
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A plugged filter drier
A restricted metering device

46. 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 plugged filter drier
An uninsulated TXV sensing bulb
Both technicians are incorrect

47. 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
A vacuum test+oil traces around fittings+soap bubble solution
Both technicians are incorrect
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An undercharged system+insufficient airflow over the evaporator coil

48. A liquid-charged TXV bulb will...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An overcharged system
Always have some liquid present in the bulb and diaphragm
An overcharged system

49. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
The system has been overcharged+The system has air trapped in the condenser
High superheat and low discharge pressure
Increases starting torque

50. 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
The sight glass is full of liquid+the sight glass is full of gas
Low superheat