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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 hard-start kit for an air conditioning system...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Increases starting torque
An overcharged system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

2. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It would cause the low-side pressure to decrease
Low superheat
Technician B

3. 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
Technician B
The sensing bulb at a lower temperature than the valve body
High superheat and low discharge pressure
Run with high head and high suction pressure

4. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Technician B
The superheat increases and the subcooling decreases
Low superheat
An open internal overload protector

5. Which of the following could be the cause for a system's discharge and suction pressure being low...
Always have some liquid present in the bulb and diaphragm
High superheat and low discharge pressure
A restricted metering device
An undercharged system+insufficient airflow over the evaporator coil

6. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A start capacitor and a solid-state relay
The internal overload is opened

7. What are the symptoms of an air conditioning system that has a low charge...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The low-side pressure will decrease and the evaporator coil will be partially frosted
High superheat and low discharge pressure
Always have some liquid present in the bulb and diaphragm

8. Which of the following can cause excessive subcooling...
Technician A is correct
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
An overcharged system

9. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
The oil pump pressure and the crankcase pressure
High suction pressure and low superheat
An uninsulated suction line and a restricted metering device

10. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
Current in the compressor circuit
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Dirty condenser - bent condenser fins - and air recirculating over the condenser

11. 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
Contains a solenoid coil and one or more sets of contacts
Low discharge pressure - high suction pressure - and low amp draw
The superheat will increase and the low-side pressure will decrease

12. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
110-120
Current in the compressor circuit

13. What is the purpose of an EPR valve...
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

14. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B
Low discharge pressure - high suction pressure - and low amp draw
The superheat increases and the subcooling decreases

15. What type of problems can be caused by an oversized air conditioning system...
Technician A is correct
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Short cycling and insufficient dehumidification
Technician B

16. A restricted air filter in an air conditioning system can be identified by...
Technician A
Low superheat
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An undercharged system+insufficient airflow over the evaporator coil

17. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The internal overload is opened
An increase in low-side pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are incorrect

18. What is the purpose of a CPR valve...
Rise more than normal
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure
It is used to control refrigerant pressure in the compressor crankcase

19. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A start capacitor and a solid-state relay
110-120
An overcharged system
An increase in low-side pressure

20. What are the symptoms of an air conditioning system that has a low charge...
The discharge pressure increases and the amperage increases
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The low-side pressure will decrease and the evaporator coil will be partially frosted
High superheat and low discharge pressure

21. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A plugged filter drier
The external equalizer could be plugged

22. 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
Clean the condenser coil
Increases starting torque
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B

23. 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...
High superheat and low discharge pressure
Partially frosted evaporator and high superheat
Short cycling and insufficient dehumidification
An overcharged system

24. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
Whenever necessary
Both technicians are correct
('Y' and 'C') and ('G' and 'C')

25. 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
Both technicians are incorrect
Increases starting torque
Both technicians are incorrect

26. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An open internal overload protector
Technician B

27. What problem or problems can cause low discharge and suction pressure...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An undercharged system+insufficient airflow over the evaporator coil
Clean the condenser coil
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

28. 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
Current in the compressor circuit
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An open internal overload protector
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

29. 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
Technician B
A low refrigerant charge
The external equalizer could be plugged
Dirty condenser - bent condenser fins - and air recirculating over the condenser

30. 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
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 missing air filter+improper rotation of the indoor blower+blower too small

31. 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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32. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated suction line and a restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure
Low discharge pressure - high suction pressure - and low amp draw
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

33. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A plugged filter drier
Lack of airflow
A restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure

34. 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...
Rise more than normal
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The external equalizer could be plugged
High superheat and low discharge pressure

35. 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
A vacuum test+oil traces around fittings+soap bubble solution
Broken rings+broken valves+seized bearings
An uninsulated suction line and a restricted metering device
An overcharged system

36. What is the common cause of a compressor burnout...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
110-120

37. The internal overload of an air conditioning compressor senses winding temperature and...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Always have some liquid present in the bulb and diaphragm
The system has been overcharged+The system has air trapped in the condenser
Current in the compressor circuit

38. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
A sensing bulb improperly connected to the suction line
Technician B
An acid-core suction line drier
110-120

39. 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 in low-side pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Both technicians are incorrect
The discharge pressure increases and the amperage increases

40. 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 dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
A blown fuse
Low discharge pressure - high suction pressure - and low amp draw

41. The temperature range of the suction line from an air conditioning system should be...
50-65
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Clean the condenser coil

42. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
'G' to 'C'
Always have some liquid present in the bulb and diaphragm
It would cause the low-side pressure to decrease

43. When using a vapor-charged TXV bulb - it is necessary to have...
The oil pump pressure and the crankcase pressure
50-65
A start capacitor and a solid-state relay
The sensing bulb at a lower temperature than the valve body

44. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A low refrigerant charge
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
It is used to control refrigerant pressure in the compressor crankcase

45. 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
An undercharge and low ambient conditions
Condenser fans operating during a low ambient condition and a low suction pressure
The sensing bulb at a lower temperature than the valve body

46. Why is it unsafe to operate an air conditioning system with a low charge...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The internal overload is opened
50-65

47. 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 fans operating during a low ambient condition and a low suction pressure
An undercharged system+insufficient airflow over the evaporator coil
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

48. 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...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A blown fuse
A sensing bulb improperly connected to the suction line
The superheat increases and the subcooling decreases

49. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Partially frosted evaporator and high superheat
An acid-core suction line drier
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
High suction pressure and low superheat

50. 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
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
110-120