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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 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
Low voltage and a faulty start relay
The external equalizer could be plugged
Technician B
The oil pump pressure and the crankcase pressure

2. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Run with high head and high suction pressure
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An undercharge and low ambient conditions

3. 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
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
Both technicians are correct
Contains a solenoid coil and one or more sets of contacts

4. A compressor having tight bearings would cause the current value to...
An uninsulated TXV sensing bulb
Rise more than normal
The system has been overcharged+The system has air trapped in the condenser
A sensing bulb improperly connected to the suction line

5. A hard-start kit for an air conditioning system...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
Increases starting torque
It keeps a constant superheat in the evaporator

6. Why is it unsafe to operate an air conditioning system with a low charge...
Both technicians are correct
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The external equalizer could be plugged

7. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Both technicians are incorrect
An undercharge and low ambient conditions
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
('Y' and 'C') and ('G' and 'C')

8. What are common methods that are used for leak-testing a system...
An open internal overload protector
3 psig
Technician B
A vacuum test+oil traces around fittings+soap bubble solution

9. Which of the following is a common cause of an excessively low superheat on a TXV system...
Technician B
A sensing bulb improperly connected to the suction line
Evaporator and compressor
Current in the compressor circuit

10. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
Whenever necessary

11. 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 A
110-120
The sight glass is full of liquid+the sight glass is full of gas
Technician B

12. 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
A missing air filter+improper rotation of the indoor blower+blower too small
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The superheat will increase and the low-side pressure will decrease
An open internal overload protector

13. What are common methods that are used for leak-testing a system...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Run with high head and high suction pressure
A vacuum test+oil traces around fittings+soap bubble solution

14. 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
Technician B
Contains a solenoid coil and one or more sets of contacts
Clean the condenser coil

15. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
A bad thermostat
An increase of air leakage from ductwork
Low superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser

16. What are the operating pressures of an oil pressure safety switch...
('Y' and 'C') and ('G' and 'C')
An acid-core suction line drier
High suction pressure and low superheat
The oil pump pressure and the crankcase pressure

17. 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...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
High superheat and low discharge pressure
Short cycling and insufficient dehumidification
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

18. 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
Technician A is correct
A defective circuit breaker
The oil pump pressure and the crankcase pressure
50-65

19. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The external equalizer could be plugged
Low superheat
A vacuum test+oil traces around fittings+soap bubble solution

20. A system that uses a thermal electric expansion valve...
An overcharged system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Partially frosted evaporator and high superheat
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

21. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Both technicians are incorrect
Lack of airflow
An increase in suction pressure and an increase in discharge pressure
Partially frosted evaporator and high superheat

22. 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
The superheat increases and the subcooling decreases
Short cycling and insufficient dehumidification
It would cause the low-side pressure to decrease
Technician B

23. 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
A restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Evaporator and compressor
Both technicians are correct

24. 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
The internal overload is opened
50-65
The external equalizer could be plugged
Clean the condenser coil

25. What are two common symptoms of refrigerant leaks in an air conditioning system...
Increases starting torque
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Partially frosted evaporator and high superheat
A start relay

26. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Lack of airflow
The superheat increases and the subcooling decreases
An undercharged system+insufficient airflow over the evaporator coil
It would cause the low-side pressure to decrease

27. 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
Broken rings+broken valves+seized bearings
A blown fuse
Technician B
It is used to control refrigerant pressure in the compressor crankcase

28. A liquid-charged TXV bulb will...
Low voltage and a faulty start relay
Always have some liquid present in the bulb and diaphragm
Technician B
Both technicians are incorrect

29. The best description of a relay would be...
High suction pressure and low superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted
Contains a solenoid coil and one or more sets of contacts
Partially frosted evaporator and high superheat

30. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Bad compressor valve
A vacuum test+oil traces around fittings+soap bubble solution
The discharge pressure increases and the amperage increases
It would cause the low-side pressure to decrease

31. A customer calls with an insufficient cooling complaint on a 90
Flooding the condenser - cycling condenser fans - and dampering condenser air
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

32. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Increases starting torque
The superheat will increase and the low-side pressure will decrease
An undercharged system+insufficient airflow over the evaporator coil
3 psig

33. A system that is operating with a clear sight glass shows...
The internal overload is opened
The sight glass is full of liquid+the sight glass is full of gas
'G' to 'C'
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

34. What problem or problems can cause low discharge and suction pressure...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician A
An undercharged system+insufficient airflow over the evaporator coil
Both technicians are correct

35. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
The external equalizer could be plugged
A sensing bulb improperly connected to the suction line
('Y' and 'C') and ('G' and 'C')

36. A system that is operating with a clear sight glass shows...
An open internal overload protector
The sight glass is full of liquid+the sight glass is full of gas
Always have some liquid present in the bulb and diaphragm
A defective circuit breaker

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
Technician A is correct
Current in the compressor circuit
A bad thermostat
An increase of air leakage from ductwork

38. Which of the following can cause excessive subcooling...
Low voltage and a faulty start relay
An overcharged system
Both technicians are correct
A vacuum test+oil traces around fittings+soap bubble solution

39. Which of the following can cause low superheat in a TXV system...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Both technicians are incorrect
An uninsulated TXV sensing bulb
A start capacitor and a solid-state relay

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 start capacitor and a solid-state relay
Always have some liquid present in the bulb and diaphragm
A blown fuse
The superheat will increase and the low-side pressure will decrease

41. A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that the system is using are-22 with the high-side pressure at 290 psig and the low-side pressure at 85 psig. The ambient temperature is 85
Technician B
Technician A
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An uninsulated suction line and a restricted metering device

42. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It would cause the low-side pressure to decrease
The superheat increases and the subcooling decreases
An undercharged system+insufficient airflow over the evaporator coil
Low voltage and a faulty start relay

43. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Low superheat
An overcharged system
A sensing bulb improperly connected to the suction line
The discharge pressure increases and the amperage increases

44. A commercial customer calls complaining that her rooftop air conditioning system is not operating. The technician arrives on the job and sets the thermostat to cooling - then notices that the indoor fan is not operating. The technician then sets the

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45. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
110-120
Technician B

46. 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...
Always have some liquid present in the bulb and diaphragm
An overcharged system
A restricted metering device
High superheat and low discharge pressure

47. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Low voltage and a faulty start relay
An increase of air leakage from ductwork
High suction pressure and low superheat
An undercharge and low ambient conditions

48. 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
An undercharge and low ambient conditions
Short cycling and insufficient dehumidification
Condenser fans operating during a low ambient condition and a low suction pressure

49. A restricted air filter in an air conditioning system can be identified by...
Low superheat
A bad thermostat
An uninsulated TXV sensing bulb
Rise more than normal

50. 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...
A blown fuse
The sensing bulb at a lower temperature than the valve body
Condenser fans operating during a low ambient condition and a low suction pressure
110-120