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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. Why is it unsafe to operate an air conditioning system with a low charge...
A low refrigerant charge
High superheat and low discharge pressure
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

2. Which of the following will cause excessive discharge pressures on an air conditioning system...
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
Clean the condenser coil
A bad thermostat

3. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
Technician B
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

4. 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
Technician B
Broken rings+broken valves+seized bearings
Lack of airflow
A plugged filter drier

5. Insufficient airflow can be caused by...
Rise more than normal
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase of air leakage from ductwork

6. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
An undercharged system+insufficient airflow over the evaporator coil
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Clean the condenser coil
'G' to 'C'

7. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A low refrigerant charge
The superheat increases and the subcooling decreases
20 to 30

8. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Evaporator and compressor
A missing air filter+improper rotation of the indoor blower+blower too small
Clean the condenser coil
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

9. 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
The sight glass is full of liquid+the sight glass is full of gas
Technician B
3 psig
The external equalizer could be plugged

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. 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
Contains a solenoid coil and one or more sets of contacts
The external equalizer could be plugged
Run with high head and high suction pressure
Technician A is correct

12. 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
An undercharge and low ambient conditions
20 to 30
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

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
Technician B
Technician B
A restricted metering device

14. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
High suction pressure and low superheat
The external equalizer could be plugged
An increase in suction pressure and an increase in discharge pressure
Low voltage and a faulty start relay

15. 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
It keeps a constant superheat in the evaporator
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A dirty condenser - recirculation of condenser air - and a defective condenser fan

16. Air filters should be replaced...
An overcharged system
Whenever necessary
('Y' and 'C') and ('G' and 'C')
An uninsulated suction line and a restricted metering device

17. A compressor having tight bearings would cause the current value to...
The internal overload is opened
Rise more than normal
Current in the compressor circuit
An open internal overload protector

18. What are the symptoms of a TXV air conditioning system if it has lost its charge...
110-120
Short cycling and insufficient dehumidification
The superheat will increase and the low-side pressure will decrease
'G' to 'C'

19. 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 thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Always have some liquid present in the bulb and diaphragm
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A defective circuit breaker

20. 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
The discharge pressure increases and the amperage increases
Technician B
A start relay
The superheat increases and the subcooling decreases

21. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Both technicians are incorrect
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

22. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
It is used to control refrigerant pressure in the compressor crankcase
Increases starting torque
High superheat and low discharge pressure

23. What are the symptoms of a TXV air conditioning system if it has lost its charge...
A blown fuse
Rise more than normal
Low discharge pressure - high suction pressure - and low amp draw
The superheat will increase and the low-side pressure will decrease

24. Which of the following could be the cause for a system's discharge and suction pressure being low...
Short cycling and insufficient dehumidification
An open internal overload protector
Technician B
A restricted metering device

25. A restricted air filter in an air conditioning system can be identified by...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Low superheat
It keeps a constant superheat in the evaporator
An overcharged system

26. When using a vapor-charged TXV bulb - it is necessary to have...
Technician B
Increases starting torque
The sensing bulb at a lower temperature than the valve body
The superheat increases and the subcooling decreases

27. 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
A missing air filter+improper rotation of the indoor blower+blower too small
Lack of airflow
Condenser fans operating during a low ambient condition and a low suction pressure
Both technicians are incorrect

28. What are three methods for controlling a system's high-side pressure during low ambient conditions...
The superheat increases and the subcooling decreases
Flooding the condenser - cycling condenser fans - and dampering condenser air
50-65
Low discharge pressure - high suction pressure - and low amp draw

29. What type of problems can be caused by an oversized air conditioning system...
Technician A is correct
It is used to control refrigerant pressure in the compressor crankcase
The sight glass is full of liquid+the sight glass is full of gas
Short cycling and insufficient dehumidification

30. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
('Y' and 'C') and ('G' and 'C')
A missing air filter+improper rotation of the indoor blower+blower too small
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

31. The temperature range of the suction line from an air conditioning system should be...
An overcharged system
The sensing bulb at a lower temperature than the valve body
50-65
110-120

32. A liquid-charged TXV bulb will...
Rise more than normal
Technician B
Always have some liquid present in the bulb and diaphragm
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

33. What causes the automatic expansion valve to close...
Run with high head and high suction pressure
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An increase in low-side pressure

34. 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 vacuum test+oil traces around fittings+soap bubble solution
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
A missing air filter+improper rotation of the indoor blower+blower too small

35. A hard-start kit consists of...
Run with high head and high suction pressure
A start capacitor and a solid-state relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A missing air filter+improper rotation of the indoor blower+blower too small

36. 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...
It is used to control refrigerant pressure in the compressor crankcase
A defective circuit breaker
High superheat and low discharge pressure
A low refrigerant charge

37. What is the purpose of a CPR valve...
High suction pressure and low superheat
Technician B
It is used to control refrigerant pressure in the compressor crankcase
An increase of air leakage from ductwork

38. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Both technicians are correct
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The superheat will increase and the low-side pressure will decrease
An overcharged system

39. A hard-start kit for an air conditioning system...
The sensing bulb at a lower temperature than the valve body
Run with high head and high suction pressure
A blown fuse
Increases starting torque

40. 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 uninsulated TXV sensing bulb
An acid-core suction line drier
Both technicians are incorrect
Partially frosted evaporator and high superheat

41. The temperature range of the suction line from an air conditioning system should be...
Technician A is correct
50-65
Whenever necessary
Technician B

42. Which of the following is a possible cause for a compressor to overheat...
A bad thermostat
A low refrigerant charge
Lack of airflow
Technician B

43. Insufficient airflow can be caused by...
Clean the condenser coil
The internal overload is opened
An increase of air leakage from ductwork
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

44. What is the common cause of a compressor burnout...
A start relay
Run with high head and high suction pressure
Technician A is correct
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

45. The internal overload of an air conditioning compressor senses winding temperature and...
Technician A is correct
Technician A
A blown fuse
Current in the compressor circuit

46. A system that is operating with a clear sight glass shows...
Condenser fans operating during a low ambient condition and a low suction pressure
Clean the condenser coil
The sight glass is full of liquid+the sight glass is full of gas
Run with high head and high suction pressure

47. The internal overload of an air conditioning compressor senses winding temperature and...
Low superheat
Current in the compressor circuit
Technician B
('Y' and 'C') and ('G' and 'C')

48. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
It is used to control refrigerant pressure in the compressor crankcase
The discharge pressure increases and the amperage increases
The sight glass is full of liquid+the sight glass is full of gas

49. Why is it unsafe to operate an air conditioning system with a low charge...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A vacuum test+oil traces around fittings+soap bubble solution

50. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
Technician B
An open internal overload protector
A defective circuit breaker