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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 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
Condenser fans operating during a low ambient condition and a low suction pressure
50-65
An overcharged system

2. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A blown fuse
An uninsulated TXV sensing bulb
The internal overload is opened

3. 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
Technician B
Technician A is correct
A low refrigerant charge

4. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
A restricted metering device
An increase in suction pressure and an increase in discharge pressure
An undercharge and low ambient conditions
Dirty condenser - bent condenser fins - and air recirculating over the condenser

5. Air filters should be replaced...
50-65
The oil pump pressure and the crankcase pressure
Whenever necessary
High suction pressure and low superheat

6. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An overcharged system
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan

7. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Broken rings+broken valves+seized bearings
Both technicians are incorrect
An increase in suction pressure and an increase in discharge pressure
The internal overload is opened

8. 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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9. 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
An undercharge and low ambient conditions
Technician B
An overcharged system
Both technicians are incorrect

10. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Evaporator and compressor
Partially frosted evaporator and high superheat
Technician A is correct

11. 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
3 psig
Lack of airflow
Technician B

12. What problem or problems can cause low discharge and suction pressure...
The sight glass is full of liquid+the sight glass is full of gas
An undercharged system+insufficient airflow over the evaporator coil
A start capacitor and a solid-state relay
The sensing bulb at a lower temperature than the valve body

13. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
It is used to control refrigerant pressure in the compressor crankcase
Run with high head and high suction pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

14. The internal overload of an air conditioning compressor senses winding temperature and...
Technician B
Current in the compressor circuit
An increase of air leakage from ductwork
Technician B

15. A restricted air filter in an air conditioning system can be identified by...
A missing air filter+improper rotation of the indoor blower+blower too small
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
Low superheat

16. What are the symptoms of an air conditioning system that has a low charge...
Condenser fans operating during a low ambient condition and a low suction pressure
The internal overload is opened
The system has been overcharged+The system has air trapped in the condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted

17. 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
A restricted metering device
An open internal overload protector
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Always have some liquid present in the bulb and diaphragm

18. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
The low-side pressure will decrease and the evaporator coil will be partially frosted
Low discharge pressure - high suction pressure - and low amp draw
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

19. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A missing air filter+improper rotation of the indoor blower+blower too small
Lack of airflow
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

20. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
An increase in low-side pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

21. 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
Both technicians are incorrect
Technician B
A blown fuse
Evaporator and compressor

22. 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
It keeps a constant superheat in the evaporator
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
Always have some liquid present in the bulb and diaphragm

23. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A missing air filter+improper rotation of the indoor blower+blower too small
An undercharge and low ambient conditions
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

24. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
Low discharge pressure - high suction pressure - and low amp draw
The superheat increases and the subcooling decreases
A defective circuit breaker

25. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
'G' to 'C'
An open internal overload protector

26. 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
110-120
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Broken rings+broken valves+seized bearings
High suction pressure and low superheat

27. 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 thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An increase in low-side pressure
A blown fuse
Contains a solenoid coil and one or more sets of contacts

28. 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 bad thermostat
An undercharged system+insufficient airflow over the evaporator coil
Technician B
Both technicians are incorrect

29. A restricted air filter in an air conditioning system can be identified by...
High suction pressure and low superheat
Low superheat
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

30. Which of the following is a possible cause for a compressor to overheat...
Technician B
A low refrigerant charge
Flooding the condenser - cycling condenser fans - and dampering condenser air
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

31. What three things can prevent an air conditioning system from releasing heat at the proper rate...
An open internal overload protector
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in low-side pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

32. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An undercharge and low ambient conditions
High superheat and low discharge pressure
The superheat increases and the subcooling decreases

33. 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
An overcharged system
Both technicians are correct
20 to 30
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

34. 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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35. The temperature range of the suction line from an air conditioning system should be...
50-65
High superheat and low discharge pressure
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

36. A party-store owner tried to adjust the water valve on his water-cooled condensing unit - then he called for assistance from an HVAC/are service technician. It was found that when servicing the unit - the outlet water temperature was too low. Technic
Both technicians are incorrect
'G' to 'C'
Technician B
A vacuum test+oil traces around fittings+soap bubble solution

37. Air filters should be replaced...
A missing air filter+improper rotation of the indoor blower+blower too small
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Whenever necessary
Evaporator and compressor

38. A liquid-charged TXV bulb will...
The discharge pressure increases and the amperage increases
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Always have some liquid present in the bulb and diaphragm
An open internal overload protector

39. The best description of a relay would be...
Condenser fans operating during a low ambient condition and a low suction pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
Contains a solenoid coil and one or more sets of contacts
An uninsulated suction line and a restricted metering device

40. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
High superheat and low discharge pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B

41. What type of problems can be caused by an oversized air conditioning system...
A start relay
An undercharge and low ambient conditions
Short cycling and insufficient dehumidification
Bad compressor valve

42. 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 start relay
Technician B
A start relay

43. 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
50-65
Technician B
A defective circuit breaker

44. Which of the following can cause excessive subcooling...
110-120
An overcharged system
20 to 30
An increase in suction pressure and an increase in discharge pressure

45. What causes the automatic expansion valve to close...
The discharge pressure increases and the amperage increases
An uninsulated suction line and a restricted metering device
An increase in low-side pressure
Both technicians are incorrect

46. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
110-120
Technician B

47. 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
It is used to control refrigerant pressure in the compressor crankcase
Both technicians are correct
Technician A
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

48. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Whenever necessary
An increase in suction pressure and an increase in discharge pressure
An increase of air leakage from ductwork
Low voltage and a faulty start relay

49. 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
Broken rings+broken valves+seized bearings
It is used to control refrigerant pressure in the compressor crankcase
A plugged filter drier
A defective circuit breaker

50. 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...
It keeps a constant superheat in the evaporator
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Whenever necessary
Low voltage and a faulty start relay