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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 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 start relay
A low refrigerant charge
Both technicians are incorrect
Rise more than normal

2. 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
Technician B
Technician A is correct
Bad compressor valve
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

3. 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
Bad compressor valve
Whenever necessary
Both technicians are incorrect
Rise more than normal

4. The internal overload of an air conditioning compressor senses winding temperature and...
An overcharged system
Current in the compressor circuit
A restricted metering device
The low-side pressure will decrease and the evaporator coil will be partially frosted

5. Air filters should be replaced...
A plugged filter drier
Whenever necessary
An undercharged system+insufficient airflow over the evaporator coil
3 psig

6. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B

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...
Contains a solenoid coil and one or more sets of contacts
Increases starting torque
High superheat and low discharge pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

8. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
High suction pressure and low superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An uninsulated TXV sensing bulb
Condenser fans operating during a low ambient condition and a low suction pressure

9. What component is most often the cause of a start capacitor failure...
Technician B
An undercharge and low ambient conditions
An open internal overload protector
A start relay

10. A hard-start kit consists of...
It would cause the low-side pressure to decrease
An uninsulated suction line and a restricted metering device
A start capacitor and a solid-state relay
The internal overload is opened

11. A restricted air filter in an air conditioning system can be identified by...
Low superheat
An increase of air leakage from ductwork
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B

12. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
The external equalizer could be plugged
An open internal overload protector
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Bad compressor valve

13. 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
An overcharged system
An uninsulated suction line and a restricted metering device
The superheat will increase and the low-side pressure will decrease

14. A system that is operating with a clear sight glass shows...
Flooding the condenser - cycling condenser fans - and dampering condenser air
3 psig
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The sight glass is full of liquid+the sight glass is full of gas

15. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Short cycling and insufficient dehumidification
Bad compressor valve
Increases starting torque
The external equalizer could be plugged

16. Which of the following will cause excessive discharge pressures on an air conditioning system...
The system has been overcharged+The system has air trapped in the condenser
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
Flooding the condenser - cycling condenser fans - and dampering condenser air

17. 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...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Bad compressor valve
A blown fuse
A restricted metering device

18. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
An undercharge and low ambient conditions
The discharge pressure increases and the amperage increases
The internal overload is opened
Low discharge pressure - high suction pressure - and low amp draw

19. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A plugged filter drier
Both technicians are correct
Contains a solenoid coil and one or more sets of contacts

20. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are incorrect
Technician B
The superheat increases and the subcooling decreases

21. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...

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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
Both technicians are correct
The discharge pressure increases and the amperage increases
Technician B
High superheat and low discharge pressure

23. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An increase in suction pressure and an increase in discharge pressure
A low refrigerant charge

24. 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
The superheat increases and the subcooling decreases
The sensing bulb at a lower temperature than the valve body
Technician B
The sight glass is full of liquid+the sight glass is full of gas

25. What component is most often the cause of a start capacitor failure...
An uninsulated suction line and a restricted metering device
A start relay
Lack of airflow
It keeps a constant superheat in the evaporator

26. What type of problems can be caused by an oversized air conditioning system...
Technician A is correct
Short cycling and insufficient dehumidification
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

27. A hard-start kit for an air conditioning system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Low discharge pressure - high suction pressure - and low amp draw
The oil pump pressure and the crankcase pressure
Increases starting torque

28. A system that uses a thermal electric expansion valve...
Bad compressor valve
A start capacitor and a solid-state relay
High suction pressure and low superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

29. A customer calls and says that her air conditioning system is not cooling properly. Upon arrival - a technician notices that the suction line and compressor have frost buildup. Technician A says that the problem is probably a low charge. Technician B
Whenever necessary
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
It would cause the low-side pressure to decrease

30. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
110-120
Low superheat
Low superheat

31. What is the purpose of a CPR valve...
Partially frosted evaporator and high superheat
It is used to control refrigerant pressure in the compressor crankcase
Contains a solenoid coil and one or more sets of contacts
Evaporator and compressor

32. Superheat is found in an air conditioning system in the...
Contains a solenoid coil and one or more sets of contacts
Evaporator and compressor
Clean the condenser coil
The low-side pressure will decrease and the evaporator coil will be partially frosted

33. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
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
Evaporator and compressor

34. The best description of a relay would be...
Technician B
Contains a solenoid coil and one or more sets of contacts
Technician B
A vacuum test+oil traces around fittings+soap bubble solution

35. 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 B
Technician A
The internal overload is opened
Run with high head and high suction pressure

36. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Broken rings+broken valves+seized bearings
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
Bad compressor valve

37. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
The discharge pressure increases and the amperage increases
Both technicians are incorrect
Technician B

38. 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
The discharge pressure increases and the amperage increases
The oil pump pressure and the crankcase pressure
An increase in low-side pressure
A defective circuit breaker

39. A customer calls with an insufficient cooling complaint on a 90
The external equalizer could be plugged
Technician B
Bad compressor valve
It is used to control refrigerant pressure in the compressor crankcase

40. Which of the following is a possible cause for a compressor to overheat...
A plugged filter drier
Technician B
A low refrigerant charge
Technician B

41. 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
Condenser fans operating during a low ambient condition and a low suction pressure
Technician A
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

42. Air filters should be replaced...
Whenever necessary
Low discharge pressure - high suction pressure - and low amp draw
A missing air filter+improper rotation of the indoor blower+blower too small
Low superheat

43. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Condenser fans operating during a low ambient condition and a low suction pressure
An overcharged system
High suction pressure and low superheat
Technician A is correct

44. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
110-120
It keeps a constant superheat in the evaporator
Rise more than normal
The superheat increases and the subcooling decreases

45. 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
Run with high head and high suction pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Rise more than normal

46. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Contains a solenoid coil and one or more sets of contacts
The superheat will increase and the low-side pressure will decrease
A bad thermostat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

47. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician A is correct
The superheat will increase and the low-side pressure will decrease

48. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Both technicians are incorrect
A blown fuse
20 to 30
It would cause the low-side pressure to decrease

49. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The system has been overcharged+The system has air trapped in the condenser
An increase in suction pressure and an increase in discharge pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
Low discharge pressure - high suction pressure - and low amp draw

50. What causes the automatic expansion valve to close...
An increase in low-side pressure
The sight glass is full of liquid+the sight glass is full of gas
An overcharged system
Broken rings+broken valves+seized bearings