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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. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Increases starting torque
The discharge pressure increases and the amperage increases
The external equalizer could be plugged
The superheat will increase and the low-side pressure will decrease

2. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A vacuum test+oil traces around fittings+soap bubble solution
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
Rise more than normal

3. A restricted air filter in an air conditioning system can be identified by...
Evaporator and compressor
Current in the compressor circuit
('Y' and 'C') and ('G' and 'C')
Low superheat

4. 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
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A bad thermostat
An overcharged system
An undercharged system+insufficient airflow over the evaporator coil

5. Why is it unsafe to operate an air conditioning system with a low charge...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Run with high head and high suction pressure
An undercharged system+insufficient airflow over the evaporator coil

6. 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
An undercharged system+insufficient airflow over the evaporator coil
Technician A
Increases starting torque

7. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Contains a solenoid coil and one or more sets of contacts
The low-side pressure will decrease and the evaporator coil will be partially frosted

8. What are the symptoms of an air conditioning system that has a low charge...
An uninsulated suction line and a restricted metering device
The low-side pressure will decrease and the evaporator coil will be partially frosted
The superheat increases and the subcooling decreases
The superheat increases and the subcooling decreases

9. What are common methods that are used for leak-testing a system...
Broken rings+broken valves+seized bearings
Technician B
Both technicians are correct
A vacuum test+oil traces around fittings+soap bubble solution

10. What are the operating pressures of an oil pressure safety switch...
A missing air filter+improper rotation of the indoor blower+blower too small
The oil pump pressure and the crankcase pressure
A sensing bulb improperly connected to the suction line
Bad compressor valve

11. What is the purpose of an EPR valve...
Run with high head and high suction pressure
A low refrigerant charge
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Current in the compressor circuit

12. 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...
('Y' and 'C') and ('G' and 'C')
3 psig
Condenser fans operating during a low ambient condition and a low suction pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

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
Technician B
The oil pump pressure and the crankcase pressure
Both technicians are incorrect

14. What are the operating pressures of an oil pressure safety switch...
The superheat increases and the subcooling decreases
Lack of airflow
An acid-core suction line drier
The oil pump pressure and the crankcase pressure

15. Superheat is found in an air conditioning system in the...
'G' to 'C'
Both technicians are correct
Evaporator and compressor
The discharge pressure increases and the amperage increases

16. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An open internal overload protector
Evaporator and compressor
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
'G' to 'C'

17. 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
Lack of airflow
Lack of airflow
Technician B
A low refrigerant charge

18. What is the purpose of an EPR valve...
Both technicians are correct
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Low voltage and a faulty start relay

19. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

20. What is the purpose of the TXV...
It is used to control refrigerant pressure in the compressor crankcase
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
High suction pressure and low superheat
It keeps a constant superheat in the evaporator

21. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Current in the compressor circuit
The discharge pressure increases and the amperage increases
Technician B
Partially frosted evaporator and high superheat

22. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
A start relay
A sensing bulb improperly connected to the suction line
Technician B

23. A system that uses a thermal electric expansion valve...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

24. What problem or problems can cause low discharge and suction pressure...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The sight glass is full of liquid+the sight glass is full of gas
An undercharge and low ambient conditions
An undercharged system+insufficient airflow over the evaporator coil

25. Which of the following can cause excessive subcooling...
An overcharged system
A start capacitor and a solid-state relay
Lack of airflow
A low refrigerant charge

26. What component is most often the cause of a start capacitor failure...
A start relay
It keeps a constant superheat in the evaporator
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Short cycling and insufficient dehumidification

27. What is the purpose of a CPR valve...
A restricted metering device
Current in the compressor circuit
A blown fuse
It is used to control refrigerant pressure in the compressor crankcase

28. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A low refrigerant charge
Bad compressor valve
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
'G' to 'C'

29. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
An overcharged system
Run with high head and high suction pressure
'G' to 'C'
50-65

30. 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 internal overload is opened
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
It is used to control refrigerant pressure in the compressor crankcase

31. A hard-start kit consists of...
Current in the compressor circuit
A restricted metering device
A start capacitor and a solid-state relay
Flooding the condenser - cycling condenser fans - and dampering condenser air

32. Air filters should be replaced...
Technician B
110-120
'G' to 'C'
Whenever necessary

33. A customer calls with an insufficient cooling complaint on a 90
The discharge pressure increases and the amperage increases
3 psig
Clean the condenser coil
Technician B

34. 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 low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A bad thermostat

35. 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
An overcharged system
Technician B
The external equalizer could be plugged

36. 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
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
Short cycling and insufficient dehumidification
Technician B

37. Superheat is found in an air conditioning system in the...
Run with high head and high suction pressure
Evaporator and compressor
The oil pump pressure and the crankcase pressure
Technician B

38. 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
The low-side pressure will decrease and the evaporator coil will be partially frosted
A plugged filter drier
Whenever necessary
Both technicians are incorrect

39. 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...
Technician B
Low voltage and a faulty start relay
Both technicians are incorrect
Broken rings+broken valves+seized bearings

40. 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
Technician B
The sensing bulb at a lower temperature than the valve body
Lack of airflow
High superheat and low discharge pressure

41. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
The superheat increases and the subcooling decreases
Contains a solenoid coil and one or more sets of contacts
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Low discharge pressure - high suction pressure - and low amp draw

42. A system that is operating with a clear sight glass shows...
3 psig
A blown fuse
The sight glass is full of liquid+the sight glass is full of gas
An undercharged system+insufficient airflow over the evaporator coil

43. 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 overcharged system
It is used to control refrigerant pressure in the compressor crankcase
Technician B
A defective circuit breaker

44. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An overcharged system
A missing air filter+improper rotation of the indoor blower+blower too small
A dirty condenser - recirculation of condenser air - and a defective condenser fan

45. 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...
Technician B
'G' to 'C'
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

46. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Low superheat
The superheat will increase and the low-side pressure will decrease
Evaporator and compressor

47. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
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
Whenever necessary
A dirty condenser - recirculation of condenser air - and a defective condenser fan

48. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B
An increase in suction pressure and an increase in discharge pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air

49. 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
An acid-core suction line drier
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
The internal overload is opened

50. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Rise more than normal
Increases starting torque
It would cause the low-side pressure to decrease
The sight glass is full of liquid+the sight glass is full of gas

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NATE Air Conditioning Troubleshooting

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