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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. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Technician B
20 to 30
Low discharge pressure - high suction pressure - and low amp draw
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

2. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Technician B
Technician B
110-120
An increase of air leakage from ductwork

3. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Both technicians are incorrect
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
An acid-core suction line drier

4. What are the symptoms of an air conditioning system that has a low charge...
Technician B
An undercharge and low ambient conditions
The low-side pressure will decrease and the evaporator coil will be partially frosted
The superheat will increase and the low-side pressure will decrease

5. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An undercharged system+insufficient airflow over the evaporator coil
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

6. A liquid-charged TXV bulb will...
Technician B
An overcharged system
Always have some liquid present in the bulb and diaphragm
Partially frosted evaporator and high superheat

7. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Low discharge pressure - high suction pressure - and low amp draw
The superheat increases and the subcooling decreases
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

8. A restricted air filter in an air conditioning system can be identified by...
Technician B
Low superheat
High suction pressure and low superheat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

9. 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 increase of air leakage from ductwork
The oil pump pressure and the crankcase pressure
Both technicians are incorrect
The sight glass is full of liquid+the sight glass is full of gas

10. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Flooding the condenser - cycling condenser fans - and dampering condenser air
3 psig
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
High superheat and low discharge pressure

11. A system that uses a thermal electric expansion valve...
The superheat increases and the subcooling decreases
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The discharge pressure increases and the amperage increases
Rise more than normal

12. 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
A missing air filter+improper rotation of the indoor blower+blower too small
Partially frosted evaporator and high superheat
A defective circuit breaker
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

13. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An open internal overload protector
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

14. 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
The oil pump pressure and the crankcase pressure
Both technicians are correct
An acid-core suction line drier
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

15. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are correct
Technician B

16. 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
Both technicians are incorrect
An overcharged system
The superheat will increase and the low-side pressure will decrease
Clean the condenser coil

17. 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 internal overload is opened
The superheat will increase and the low-side pressure will decrease
The sensing bulb at a lower temperature than the valve body
It would cause the low-side pressure to decrease

18. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

19. 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 blown fuse
Lack of airflow
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The discharge pressure increases and the amperage increases

20. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An open internal overload protector
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
High superheat and low discharge pressure

21. What causes the automatic expansion valve to close...
An increase in low-side pressure
An increase of air leakage from ductwork
The oil pump pressure and the crankcase pressure
It keeps a constant superheat in the evaporator

22. 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
Low discharge pressure - high suction pressure - and low amp draw
An increase of air leakage from ductwork
Low superheat

23. 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
A plugged filter drier
Technician B
Evaporator and compressor
The superheat increases and the subcooling decreases

24. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Broken rings+broken valves+seized bearings
Evaporator and compressor
Condenser fans operating during a low ambient condition and a low suction pressure
The superheat will increase and the low-side pressure will decrease

25. 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
Contains a solenoid coil and one or more sets of contacts
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

26. 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
Low discharge pressure - high suction pressure - and low amp draw
Technician B
It is used to control refrigerant pressure in the compressor crankcase
An open internal overload protector

27. 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
Technician B
Technician B
The external equalizer could be plugged
Evaporator and compressor

28. 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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29. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An increase in suction pressure and an increase in discharge pressure
High suction pressure and low superheat
Rise more than normal

30. 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
The discharge pressure increases and the amperage increases
Both technicians are incorrect
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

31. What causes the automatic expansion valve to close...
An overcharged system
An increase in suction pressure and an increase in discharge pressure
An increase in low-side pressure
Clean the condenser coil

32. What component is most often the cause of a start capacitor failure...
An increase of air leakage from ductwork
A start relay
An undercharge and low ambient conditions
An undercharge and low ambient conditions

33. The temperature range of the suction line from an air conditioning system should be...
50-65
The sensing bulb at a lower temperature than the valve body
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

34. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A low refrigerant charge
Contains a solenoid coil and one or more sets of contacts
The oil pump pressure and the crankcase pressure
20 to 30

35. What are the symptoms of an air conditioning system that has a low charge...
An undercharged system+insufficient airflow over the evaporator coil
A defective circuit breaker
A vacuum test+oil traces around fittings+soap bubble solution
The low-side pressure will decrease and the evaporator coil will be partially frosted

36. What is the purpose of a CPR valve...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The sensing bulb at a lower temperature than the valve body
It is used to control refrigerant pressure in the compressor crankcase
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

37. 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...
Both technicians are incorrect
Low voltage and a faulty start relay
Condenser fans operating during a low ambient condition and a low suction pressure
Evaporator and compressor

38. A hard-start kit consists of...
The superheat will increase and the low-side pressure will decrease
A start capacitor and a solid-state relay
It would cause the low-side pressure to decrease
Lack of airflow

39. When using a vapor-charged TXV bulb - it is necessary to have...
High suction pressure and low superheat
An overcharged system
Both technicians are incorrect
The sensing bulb at a lower temperature than the valve body

40. 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
Technician A is correct
50-65
An overcharged system
Both technicians are correct

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
Both technicians are incorrect
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An open internal overload protector

42. Which of the following is a common cause of an excessively low superheat on a TXV system...
A sensing bulb improperly connected to the suction line
A low refrigerant charge
A start capacitor and a solid-state relay
3 psig

43. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An acid-core suction line drier
An uninsulated suction line and a restricted metering device
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

44. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
50-65
Contains a solenoid coil and one or more sets of contacts
An uninsulated TXV sensing bulb
The superheat increases and the subcooling decreases

45. 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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46. What is the purpose of the TXV...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A sensing bulb improperly connected to the suction line
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It keeps a constant superheat in the evaporator

47. What is the common cause of a compressor burnout...
An uninsulated TXV sensing bulb
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The superheat increases and the subcooling decreases
Both technicians are incorrect

48. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Run with high head and high suction pressure
An undercharge and low ambient conditions
A plugged filter drier
50-65

49. 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...
An acid-core suction line drier
A blown fuse
110-120
Lack of airflow

50. Air filters should be replaced...
A restricted metering device
An open internal overload protector
20 to 30
Whenever necessary