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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 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
A plugged filter drier
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Clean the condenser coil
Both technicians are incorrect

2. The best description of a relay would be...
A start relay
Contains a solenoid coil and one or more sets of contacts
The external equalizer could be plugged
Both technicians are correct

3. 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...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A blown fuse
20 to 30
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

4. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The discharge pressure increases and the amperage increases
Bad compressor valve
110-120
Short cycling and insufficient dehumidification

5. Why is it unsafe to operate an air conditioning system with a low charge...
Both technicians are correct
Bad compressor valve
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

6. Which of the following could be the cause for a system's discharge and suction pressure being low...
The sensing bulb at a lower temperature than the valve body
A restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

7. 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
110-120
The superheat increases and the subcooling decreases
Both technicians are correct
Bad compressor valve

8. 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
An open internal overload protector
A vacuum test+oil traces around fittings+soap bubble solution
Both technicians are incorrect
Lack of airflow

9. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
The superheat increases and the subcooling decreases
Technician B
Low superheat

10. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An overcharged system
3 psig
An acid-core suction line drier

11. 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

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12. 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
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A missing air filter+improper rotation of the indoor blower+blower too small

13. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The superheat will increase and the low-side pressure will decrease
Both technicians are correct
It keeps a constant superheat in the evaporator
The internal overload is opened

14. What problem can cause an increase of discharge pressure and an increase of suction pressure...
It is used to control refrigerant pressure in the compressor crankcase
Increases starting torque
A restricted metering device
An overcharged system

15. A compressor having tight bearings would cause the current value to...
An undercharged system+insufficient airflow over the evaporator coil
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Rise more than normal
An uninsulated suction line and a restricted metering device

16. What are the symptoms of an air conditioning system that has a low charge...
The sensing bulb at a lower temperature than the valve body
Technician B
Low voltage and a faulty start relay
The low-side pressure will decrease and the evaporator coil will be partially frosted

17. What is the common cause of a compressor burnout...
Low voltage and a faulty start relay
It keeps a constant superheat in the evaporator
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It would cause the low-side pressure to decrease

18. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Low voltage and a faulty start relay
Technician B
An undercharge and low ambient conditions
An increase of air leakage from ductwork

19. A commercial customer calls on a 90
An undercharge and low ambient conditions
Both technicians are correct
Clean the condenser coil
The system has been overcharged+The system has air trapped in the condenser

20. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Both technicians are correct
Technician B
An overcharged system
The discharge pressure increases and the amperage increases

21. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
A vacuum test+oil traces around fittings+soap bubble solution
3 psig
The low-side pressure will decrease and the evaporator coil will be partially frosted

22. 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
A low refrigerant charge
Technician B
Evaporator and compressor
3 psig

23. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
A blown fuse
A blown fuse
It is used to control refrigerant pressure in the compressor crankcase

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
Partially frosted evaporator and high superheat
Broken rings+broken valves+seized bearings
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B

25. A system that is operating with a clear sight glass shows...
The system has been overcharged+The system has air trapped in the condenser
The sight glass is full of liquid+the sight glass is full of gas
Both technicians are correct
Short cycling and insufficient dehumidification

26. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Low discharge pressure - high suction pressure - and low amp draw
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
('Y' and 'C') and ('G' and 'C')

27. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
The oil pump pressure and the crankcase pressure
Broken rings+broken valves+seized bearings

28. A commercial customer calls on a 90
A start capacitor and a solid-state relay
The sensing bulb at a lower temperature than the valve body
An undercharge and low ambient conditions
The system has been overcharged+The system has air trapped in the condenser

29. A hard-start kit consists of...
A start capacitor and a solid-state relay
High suction pressure and low superheat
Whenever necessary
Evaporator and compressor

30. Air filters should be replaced...
Whenever necessary
High suction pressure and low superheat
The superheat increases and the subcooling decreases
The system has been overcharged+The system has air trapped in the condenser

31. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
An undercharged system+insufficient airflow over the evaporator coil
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A blown fuse

32. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A bad thermostat
An increase in suction pressure and an increase in discharge pressure
It would cause the low-side pressure to decrease

33. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The sensing bulb at a lower temperature than the valve body
The oil pump pressure and the crankcase pressure

34. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
The sight glass is full of liquid+the sight glass is full of gas
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B
High superheat and low discharge pressure

35. 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
An acid-core suction line drier
Bad compressor valve
A defective circuit breaker
Short cycling and insufficient dehumidification

36. Which of the following will cause excessive discharge pressures on an air conditioning system...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A start relay
An uninsulated TXV sensing bulb
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

37. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
The sensing bulb at a lower temperature than the valve body
Technician A
An uninsulated suction line and a restricted metering device

38. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An acid-core suction line drier
A blown fuse
Run with high head and high suction pressure
An uninsulated suction line and a restricted metering device

39. Which of the following can cause low superheat in a TXV system...
It would cause the low-side pressure to decrease
A defective circuit breaker
The superheat increases and the subcooling decreases
An uninsulated TXV sensing bulb

40. What problem or problems can cause low discharge and suction pressure...
Technician A is correct
An acid-core suction line drier
An undercharged system+insufficient airflow over the evaporator coil
'G' to 'C'

41. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Broken rings+broken valves+seized bearings
An overcharged system
('Y' and 'C') and ('G' and 'C')

42. What component is most often the cause of a start capacitor failure...
Always have some liquid present in the bulb and diaphragm
A start relay
An acid-core suction line drier
Contains a solenoid coil and one or more sets of contacts

43. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Condenser fans operating during a low ambient condition and a low suction pressure
Bad compressor valve

44. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
The superheat increases and the subcooling decreases
Always have some liquid present in the bulb and diaphragm
Run with high head and high suction pressure
'G' to 'C'

45. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Technician A is correct
Technician B
High suction pressure and low superheat
The internal overload is opened

46. The temperature range of the suction line from an air conditioning system should be...
The sight glass is full of liquid+the sight glass is full of gas
A missing air filter+improper rotation of the indoor blower+blower too small
50-65
High suction pressure and low superheat

47. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
High superheat and low discharge pressure
A restricted metering device
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Both technicians are incorrect

48. The best description of a relay would be...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician A is correct
Contains a solenoid coil and one or more sets of contacts
The system has been overcharged+The system has air trapped in the condenser

49. 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...
It would cause the low-side pressure to decrease
Technician B
50-65
The internal overload is opened

50. What are the operating pressures of an oil pressure safety switch...
Low voltage and a faulty start relay
The oil pump pressure and the crankcase pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Dirty condenser - bent condenser fins - and air recirculating over the condenser