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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. 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
An acid-core suction line drier
It keeps a constant superheat in the evaporator
Always have some liquid present in the bulb and diaphragm
Technician A is correct

2. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
Partially frosted evaporator and high superheat
An undercharged system+insufficient airflow over the evaporator coil
A sensing bulb improperly connected to the suction line

3. What three things can prevent an air conditioning system from releasing heat at the proper rate...
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
Rise more than normal
A plugged filter drier

4. 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
An overcharged system
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
20 to 30

5. 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
A vacuum test+oil traces around fittings+soap bubble solution
It keeps a constant superheat in the evaporator
Technician B
50-65

6. Which of the following will cause excessive discharge pressures on an air conditioning system...
An uninsulated suction line and 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
Low voltage and a faulty start relay
Lack of airflow

7. A restricted air filter in an air conditioning system can be identified by...
Technician B
Short cycling and insufficient dehumidification
Current in the compressor circuit
Low superheat

8. 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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Low superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted

9. A customer calls with an insufficient cooling complaint on a 90
An increase in suction pressure and an increase in discharge pressure
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Both technicians are incorrect

10. 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
The superheat will increase and the low-side pressure will decrease
A restricted metering device
Technician A is correct
Evaporator and compressor

11. A system that is operating with a clear sight glass shows...
A start capacitor and a solid-state relay
An increase of air leakage from ductwork
The sight glass is full of liquid+the sight glass is full of gas
Broken rings+broken valves+seized bearings

12. 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
A low refrigerant charge
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

13. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
'G' to 'C'
3 psig

14. The internal overload of an air conditioning compressor senses winding temperature and...
110-120
Current in the compressor circuit
The system has been overcharged+The system has air trapped in the condenser
Rise more than normal

15. The internal overload of an air conditioning compressor senses winding temperature and...
Bad compressor valve
High suction pressure and low superheat
Current in the compressor circuit
Technician A

16. 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
Both technicians are incorrect
A start capacitor and a solid-state relay
It keeps a constant superheat in the evaporator
Broken rings+broken valves+seized bearings

17. 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
The external equalizer could be plugged
High suction pressure and low superheat
The superheat increases and the subcooling decreases
A missing air filter+improper rotation of the indoor blower+blower too small

18. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

19. 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
('Y' and 'C') and ('G' and 'C')
A dirty condenser - recirculation of condenser air - and a defective condenser fan
50-65

20. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
A plugged filter drier
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Whenever necessary
Bad compressor valve

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 start capacitor and a solid-state relay
Rise more than normal
A defective circuit breaker
Current in the compressor circuit

22. What are the operating pressures of an oil pressure safety switch...
Evaporator and compressor
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The oil pump pressure and the crankcase pressure

23. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
The sensing bulb at a lower temperature than the valve body
Technician B
Run with high head and high suction pressure
A start relay

24. A customer calls with an insufficient cooling complaint on a 90
A start relay
The superheat will increase and the low-side pressure will decrease
Technician B
The sensing bulb at a lower temperature than the valve body

25. 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
An increase in low-side pressure
Technician B
An increase of air leakage from ductwork
Dirty condenser - bent condenser fins - and air recirculating over the condenser

26. What are the operating pressures of an oil pressure safety switch...
50-65
Current in the compressor circuit
An increase in low-side pressure
The oil pump pressure and the crankcase pressure

27. What are two common symptoms of a rooftop air conditioning system that operates with a reverse-acting high-pressure control stuck in the closed position...
Always have some liquid present in the bulb and diaphragm
Condenser fans operating during a low ambient condition and a low suction pressure
Partially frosted evaporator and high superheat
A dirty condenser - recirculation of condenser air - and a defective condenser fan

28. 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...
The superheat increases and the subcooling decreases
Low voltage and a faulty start relay
Flooding the condenser - cycling condenser fans - and dampering condenser air
A bad thermostat

29. 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
Low discharge pressure - high suction pressure - and low amp draw
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

30. What are the symptoms of an air conditioning system that has a low charge...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The low-side pressure will decrease and the evaporator coil will be partially frosted
The discharge pressure increases and the amperage increases
Flooding the condenser - cycling condenser fans - and dampering condenser air

31. 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
An increase in suction pressure and an increase in discharge pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B

32. Which of the following can cause low superheat in a TXV system...
Low voltage and a faulty start relay
An uninsulated TXV sensing bulb
Always have some liquid present in the bulb and diaphragm
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

33. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
3 psig
Technician B
The superheat increases and the subcooling decreases
An acid-core suction line drier

34. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A plugged filter drier
An uninsulated suction line and a restricted metering device
Technician B
A start relay

35. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
Bad compressor valve
The discharge pressure increases and the amperage increases
An overcharged system

36. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A start capacitor and a solid-state relay
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
110-120

37. A commercial customer calls on a 90
Evaporator and compressor
An open internal overload protector
Technician B
The system has been overcharged+The system has air trapped in the condenser

38. 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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39. Which of the following can cause excessive subcooling...
An overcharged system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
Technician B

40. 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
110-120
Whenever necessary
High superheat and low discharge pressure

41. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
A plugged filter drier
It is used to control refrigerant pressure in the compressor crankcase
An undercharge and low ambient conditions
Low voltage and a faulty start relay

42. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

43. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Low voltage and a faulty start relay
20 to 30
An undercharge and low ambient conditions
An open internal overload protector

44. 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
110-120
Increases starting torque
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

45. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An uninsulated TXV sensing bulb
Broken rings+broken valves+seized bearings
It is used to control refrigerant pressure in the compressor crankcase

46. The best description of a relay would be...
An overcharged system
A sensing bulb improperly connected to the suction line
Contains a solenoid coil and one or more sets of contacts
Whenever necessary

47. A compressor having tight bearings would cause the current value to...
Rise more than normal
Both technicians are incorrect
Partially frosted evaporator and high superheat
Current in the compressor circuit

48. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
3 psig
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
Bad compressor valve

49. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Rise more than normal
Increases starting torque
An increase of air leakage from ductwork

50. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A plugged filter drier
Evaporator and compressor
A missing air filter+improper rotation of the indoor blower+blower too small
An overcharged system