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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 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 discharge pressure increases and the amperage increases
Always have some liquid present in the bulb and diaphragm
Both technicians are correct
The superheat will increase and the low-side pressure will decrease

2. Which of the following can cause low superheat in a TXV system...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A sensing bulb improperly connected to the suction line
An uninsulated TXV sensing bulb
Technician A

3. 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...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An acid-core suction line drier
The internal overload is opened
A blown fuse

4. 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
Low voltage and a faulty start relay
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
Always have some liquid present in the bulb and diaphragm

5. 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
An undercharged system+insufficient airflow over the evaporator coil
A bad thermostat
Increases starting torque
An open internal overload protector

6. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The superheat increases and the subcooling decreases
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

7. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Technician A
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A bad thermostat
Run with high head and high suction pressure

8. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
Partially frosted evaporator and high superheat
Whenever necessary
The internal overload is opened

9. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Technician B
An acid-core suction line drier
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A dirty condenser - recirculation of condenser air - and a defective condenser fan

10. 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 dirty condenser - recirculation of condenser air - and a defective condenser fan
The superheat increases and the subcooling decreases
Broken rings+broken valves+seized bearings
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

11. What is the purpose of an EPR valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The internal overload is opened
The superheat will increase and the low-side pressure will decrease
An overcharged system

12. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Increases starting torque
Bad compressor valve
Contains a solenoid coil and one or more sets of contacts
Flooding the condenser - cycling condenser fans - and dampering condenser air

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
A blown fuse
The internal overload is opened
Technician B
Both technicians are incorrect

14. Why is it unsafe to operate an air conditioning system with a low charge...
The external equalizer could be plugged
Bad compressor valve
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

15. Insufficient airflow can be caused by...
An open internal overload protector
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An increase of air leakage from ductwork
An undercharged system+insufficient airflow over the evaporator coil

16. A system that uses a thermal electric expansion valve...
It keeps a constant superheat in the evaporator
A start relay
The low-side pressure will decrease and the evaporator coil will be partially frosted
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

17. A commercial customer calls on a 90
Technician B
('Y' and 'C') and ('G' and 'C')
A start relay
The system has been overcharged+The system has air trapped in the condenser

18. What three things can prevent an air conditioning system from releasing heat at the proper rate...
It would cause the low-side pressure to decrease
A start capacitor and a solid-state relay
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A restricted metering device

19. 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
The sight glass is full of liquid+the sight glass is full of gas
Technician B
A start relay
Rise more than normal

20. What problem or problems can cause low discharge and suction pressure...
Run with high head and high suction pressure
An increase in suction pressure and an increase in discharge pressure
An undercharged system+insufficient airflow over the evaporator coil
A defective circuit breaker

21. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B
It keeps a constant superheat in the evaporator

22. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
Both technicians are correct
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An uninsulated TXV sensing bulb

23. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Clean the condenser coil
Technician B

24. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
High superheat and low discharge pressure
Lack of airflow
A start capacitor and a solid-state relay
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

25. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
An uninsulated suction line and a restricted metering device
('Y' and 'C') and ('G' and 'C')
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The sensing bulb at a lower temperature than the valve body

26. A restricted air filter in an air conditioning system can be identified by...
('Y' and 'C') and ('G' and 'C')
Low superheat
Technician B
3 psig

27. A hard-start kit for an air conditioning system...
The superheat increases and the subcooling decreases
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
Increases starting torque

28. 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
A restricted metering device
It is used to control refrigerant pressure in the compressor crankcase
Both technicians are correct
Technician B

29. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
'G' to 'C'
Low voltage and a faulty start relay
Technician B

30. 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
Technician A is correct
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Condenser fans operating during a low ambient condition and a low suction pressure

31. A liquid-charged TXV bulb will...
Evaporator and compressor
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The superheat increases and the subcooling decreases
Always have some liquid present in the bulb and diaphragm

32. 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
A bad thermostat
'G' to 'C'
The superheat increases and the subcooling decreases
Condenser fans operating during a low ambient condition and a low suction pressure

33. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician A is correct
Increases starting torque
An increase in suction pressure and an increase in discharge pressure

34. 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
It keeps a constant superheat in the evaporator
Current in the compressor circuit
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

35. 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...
Technician A
High superheat and low discharge pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B

36. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
An overcharged system
Technician B
An increase of air leakage from ductwork
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

37. 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
Always have some liquid present in the bulb and diaphragm
Technician A is correct
Technician B
('Y' and 'C') and ('G' and 'C')

38. 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
Technician A
The external equalizer could be plugged
A start capacitor and a solid-state relay
Both technicians are incorrect

39. Which of the following can cause excessive subcooling...
Evaporator and compressor
An overcharged system
The sensing bulb at a lower temperature than the valve body
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

40. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
Contains a solenoid coil and one or more sets of contacts
Run with high head and high suction pressure
The superheat increases and the subcooling decreases

41. 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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42. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
A bad thermostat
High superheat and low discharge pressure
An open internal overload protector

43. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
An increase in low-side pressure
3 psig
Lack of airflow
Low superheat

44. Superheat is found in an air conditioning system in the...
Technician B
Evaporator and compressor
Technician B
A vacuum test+oil traces around fittings+soap bubble solution

45. 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 can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
High superheat and low discharge pressure

46. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
The superheat increases and the subcooling decreases
Both technicians are incorrect
Bad compressor valve
A start relay

47. 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
An overcharged system
A restricted metering device

48. A restricted air filter in an air conditioning system can be identified by...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Low superheat
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B

49. What are common methods that are used for leak-testing a system...
The oil pump pressure and the crankcase pressure
The internal overload is opened
An overcharged system
A vacuum test+oil traces around fittings+soap bubble solution

50. 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
Short cycling and insufficient dehumidification
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are correct
An overcharged system