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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 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 start capacitor and a solid-state relay
Technician B
Clean the condenser coil

2. 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
A start relay
Run with high head and high suction pressure
Rise more than normal

3. 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
It is used to control refrigerant pressure in the compressor crankcase
Technician A
An increase in suction pressure and an increase in discharge pressure
Broken rings+broken valves+seized bearings

4. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A bad thermostat
Run with high head and high suction pressure
An undercharge and low ambient conditions

5. 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
The superheat increases and the subcooling decreases
The oil pump pressure and the crankcase pressure
Technician A is correct

6. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Low voltage and a faulty start relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
20 to 30
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

7. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B
Broken rings+broken valves+seized bearings

8. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A bad thermostat
Technician B

9. 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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10. Which of the following could be the cause for a system's discharge and suction pressure being low...
The system has been overcharged+The system has air trapped in the condenser
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A restricted metering device
A blown fuse

11. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
An undercharge and low ambient conditions
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Both technicians are incorrect

12. 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...
The external equalizer could be plugged
Technician B
The internal overload is opened
The superheat will increase and the low-side pressure will decrease

13. What are the symptoms of an air conditioning system that has a low charge...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A vacuum test+oil traces around fittings+soap bubble solution
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B

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

15. 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
('Y' and 'C') and ('G' and 'C')
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An uninsulated suction line and a restricted metering device
An overcharged system

16. 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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
Current in the compressor circuit

17. What are the operating pressures of an oil pressure safety switch...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The superheat will increase and the low-side pressure will decrease
Low discharge pressure - high suction pressure - and low amp draw
The oil pump pressure and the crankcase pressure

18. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
50-65
20 to 30
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

19. 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 superheat increases and the subcooling decreases
Technician B
An overcharged system
Current in the compressor circuit

20. 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
Increases starting torque
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Both technicians are incorrect
Whenever necessary

21. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
50-65
An undercharge and low ambient conditions
110-120
Both technicians are correct

22. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
An increase of air leakage from ductwork
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

23. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Current in the compressor circuit
('Y' and 'C') and ('G' and 'C')
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

24. 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
A vacuum test+oil traces around fittings+soap bubble solution
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It would cause the low-side pressure to decrease

25. What is the purpose of the TXV...
A plugged filter drier
It keeps a constant superheat in the evaporator
Condenser fans operating during a low ambient condition and a low suction pressure
The external equalizer could be plugged

26. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
Technician B
Technician A
Whenever necessary

27. A customer calls with an insufficient cooling complaint on a 90
Both technicians are incorrect
Clean the condenser coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B

28. 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 discharge pressure increases and the amperage increases
Both technicians are correct
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

29. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An overcharged system
An increase in suction pressure and an increase in discharge pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A sensing bulb improperly connected to the suction line

30. 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 vacuum test+oil traces around fittings+soap bubble solution
An undercharge and low ambient conditions
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

31. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
3 psig
The internal overload is opened
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

32. A restricted air filter in an air conditioning system can be identified by...
Technician B
Rise more than normal
Both technicians are incorrect
Low superheat

33. 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
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A bad thermostat
A start capacitor and a solid-state relay

34. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
20 to 30
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Broken rings+broken valves+seized bearings

35. A customer calls with an insufficient cooling complaint on a 90
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An uninsulated suction line and a restricted metering device

36. What component is most often the cause of a start capacitor failure...
A start relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Broken rings+broken valves+seized bearings
'G' to 'C'

37. When using a vapor-charged TXV bulb - it is necessary to have...
Run with high head and high suction pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The sensing bulb at a lower temperature than the valve body
The discharge pressure increases and the amperage increases

38. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
A vacuum test+oil traces around fittings+soap bubble solution
High superheat and low discharge pressure

39. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Whenever necessary
The superheat will increase and the low-side pressure will decrease
Low discharge pressure - high suction pressure - and low amp draw
Condenser fans operating during a low ambient condition and a low suction pressure

40. 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
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
3 psig
An undercharged system+insufficient airflow over the evaporator coil

41. 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
It is used to control refrigerant pressure in the compressor crankcase
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are incorrect
A low refrigerant charge

42. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
High suction pressure and low superheat
It would cause the low-side pressure to decrease
Both technicians are incorrect
Condenser fans operating during a low ambient condition and a low suction pressure

43. A commercial customer calls on a 90
20 to 30
The sight glass is full of liquid+the sight glass is full of gas
Evaporator and compressor
The system has been overcharged+The system has air trapped in the condenser

44. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B
A bad thermostat

45. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Condenser fans operating during a low ambient condition and a low suction pressure
High superheat and low discharge pressure
It is used to control refrigerant pressure in the compressor crankcase

46. A customer who owns a split air conditioning system complains that his system has been running but his house doesn't seem to be cooling properly. When the service technician arrives on the job - he or she finds that the indoor blower is operating and
Condenser fans operating during a low ambient condition and a low suction pressure
Clean the condenser coil
It is used to control refrigerant pressure in the compressor crankcase
'G' to 'C'

47. A hard-start kit for an air conditioning system...
An undercharge and low ambient conditions
Increases starting torque
Both technicians are incorrect
The discharge pressure increases and the amperage increases

48. 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
Increases starting torque
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

49. A compressor having tight bearings would cause the current value to...
Rise more than normal
A low refrigerant charge
Technician A
It keeps a constant superheat in the evaporator

50. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
The sight glass is full of liquid+the sight glass is full of gas
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser