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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 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
The oil pump pressure and the crankcase pressure
Technician B
Evaporator and compressor
Dirty condenser - bent condenser fins - and air recirculating over the condenser

2. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Short cycling and insufficient dehumidification
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Low discharge pressure - high suction pressure - and low amp draw
An undercharge and low ambient conditions

3. Why is it unsafe to operate an air conditioning system with a low charge...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The superheat will increase and the low-side pressure will decrease
Increases starting torque
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

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
An overcharged system
Whenever necessary
A bad thermostat
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

5. 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 undercharged system+insufficient airflow over the evaporator coil
A blown fuse
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Rise more than normal

6. Which of the following can cause low superheat in a TXV system...
A restricted metering device
The oil pump pressure and the crankcase pressure
An uninsulated TXV sensing bulb
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

7. Which of the following is a possible cause for a compressor to overheat...
110-120
Technician B
An increase of air leakage from ductwork
A low refrigerant charge

8. What causes the automatic expansion valve to close...
An increase in low-side pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician A is correct

9. Insufficient airflow can be caused by...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
50-65
An increase of air leakage from ductwork
An uninsulated TXV sensing bulb

10. 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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11. 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
Technician B
The superheat increases and the subcooling decreases
A blown fuse
A defective circuit breaker

12. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
The discharge pressure increases and the amperage increases
The internal overload is opened
A sensing bulb improperly connected to the suction line

13. What component is most often the cause of a start capacitor failure...
Clean the condenser coil
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An increase in low-side pressure
A start relay

14. What are the symptoms of a TXV air conditioning system if it has lost its charge...
An undercharged system+insufficient airflow over the evaporator coil
A vacuum test+oil traces around fittings+soap bubble solution
The superheat will increase and the low-side pressure will decrease
Clean the condenser coil

15. The temperature range of the suction line from an air conditioning system should be...
A vacuum test+oil traces around fittings+soap bubble solution
Always have some liquid present in the bulb and diaphragm
50-65
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

16. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Technician B
3 psig
Partially frosted evaporator and high superheat
Bad compressor valve

17. When using a vapor-charged TXV bulb - it is necessary to have...
An undercharged system+insufficient airflow over the evaporator coil
A start capacitor and a solid-state relay
A blown fuse
The sensing bulb at a lower temperature than the valve body

18. Which of the following can cause excessive subcooling...
An overcharged system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Rise more than normal
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

19. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An overcharged system
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A start capacitor and a solid-state relay
The internal overload is opened

20. What are the symptoms of an air conditioning system that has a low charge...
Always have some liquid present in the bulb and diaphragm
Technician B
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted

21. 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 defective circuit breaker
A low refrigerant charge
An undercharged system+insufficient airflow over the evaporator coil
Bad compressor valve

22. Which of the following is a common cause of an excessively low superheat on a TXV system...
Clean the condenser coil
A sensing bulb improperly connected to the suction line
Both technicians are incorrect
Rise more than normal

23. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
50-65
Clean the condenser coil
An undercharge and low ambient conditions

24. What are the operating pressures of an oil pressure safety switch...
Clean the condenser coil
Flooding the condenser - cycling condenser fans - and dampering condenser air
An open internal overload protector
The oil pump pressure and the crankcase pressure

25. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

26. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Bad compressor valve
A restricted metering device
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

27. The temperature range of the suction line from an air conditioning system should be...
Current in the compressor circuit
50-65
Partially frosted evaporator and high superheat
Flooding the condenser - cycling condenser fans - and dampering condenser air

28. What is the purpose of a CPR valve...
The oil pump pressure and the crankcase pressure
It is used to control refrigerant pressure in the compressor crankcase
The low-side pressure will decrease and the evaporator coil will be partially frosted
Condenser fans operating during a low ambient condition and a low suction pressure

29. Technician A says that to manually pump down an air conditioning system with a two-position service valve - the liquid line must be front-seated and the high- and low-side pressure will decrease to 0 psig when the pump-down is complete. Technician B
A defective circuit breaker
The internal overload is opened
A sensing bulb improperly connected to the suction line
Technician A is correct

30. 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
Whenever necessary
110-120
The discharge pressure increases and the amperage increases

31. 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
Technician B
A restricted metering device
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

32. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
An undercharged system+insufficient airflow over the evaporator coil
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
High superheat and low discharge pressure

33. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Technician B
Low superheat
Lack of airflow
An uninsulated TXV sensing bulb

34. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A restricted metering device
The sight glass is full of liquid+the sight glass is full of gas
It would cause the low-side pressure to decrease
A defective circuit breaker

35. The internal overload of an air conditioning compressor senses winding temperature and...
Technician A
Lack of airflow
Current in the compressor circuit
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

36. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
An overcharged system
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Evaporator and compressor
20 to 30

37. Superheat is found in an air conditioning system in the...
Technician A is correct
Evaporator and compressor
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A plugged filter drier

38. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Contains a solenoid coil and one or more sets of contacts
Technician B
Run with high head and high suction pressure

39. 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
Technician B
Whenever necessary
The discharge pressure increases and the amperage increases

40. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Technician A is correct
50-65
A missing air filter+improper rotation of the indoor blower+blower too small
An uninsulated TXV sensing bulb

41. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A defective circuit breaker
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician A is correct

42. 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
Run with high head and high suction pressure
Broken rings+broken valves+seized bearings
A low refrigerant charge
A vacuum test+oil traces around fittings+soap bubble solution

43. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
The internal overload is opened
Evaporator and compressor
A defective circuit breaker

44. What component is most often the cause of a start capacitor failure...
Low voltage and a faulty start relay
A start relay
Short cycling and insufficient dehumidification
Current in the compressor circuit

45. 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 increase in low-side pressure
A blown fuse
Low superheat
Both technicians are incorrect

46. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A restricted metering device
50-65
The superheat increases and the subcooling decreases
The low-side pressure will decrease and the evaporator coil will be partially frosted

47. When using a vapor-charged TXV bulb - it is necessary to have...
'G' to 'C'
A start capacitor and a solid-state relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The sensing bulb at a lower temperature than the valve body

48. The internal overload of an air conditioning compressor senses winding temperature and...
Technician B
Current in the compressor circuit
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An undercharge and low ambient conditions

49. Which of the following is a possible cause for a compressor to overheat...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
A low refrigerant charge
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

50. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The superheat will increase and the low-side pressure will decrease
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
High superheat and low discharge pressure
An increase in suction pressure and an increase in discharge pressure