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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. What are the symptoms of an air conditioning system that has a low charge...
Both technicians are correct
The low-side pressure will decrease and the evaporator coil will be partially frosted
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An overcharged system

2. 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 sensing bulb improperly connected to the suction line
A sensing bulb improperly connected to the suction line
Both technicians are correct
An open internal overload protector

3. 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
An overcharged system
110-120
Lack of airflow

4. 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 defective circuit breaker
Clean the condenser coil
An increase of air leakage from ductwork
3 psig

5. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A bad thermostat
Bad compressor valve
20 to 30
The superheat increases and the subcooling decreases

6. What are common methods that are used for leak-testing a system...
Both technicians are correct
50-65
A vacuum test+oil traces around fittings+soap bubble solution
An overcharged system

7. 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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8. 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...
The low-side pressure will decrease and the evaporator coil will be partially frosted
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Condenser fans operating during a low ambient condition and a low suction pressure
Rise more than normal

9. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
An increase in low-side pressure
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

10. What are the symptoms of an air conditioning system that has a low charge...
Increases starting torque
An overcharged system
The low-side pressure will decrease and the evaporator coil will be partially frosted
110-120

11. Air filters should be replaced...
A low refrigerant charge
Whenever necessary
Condenser fans operating during a low ambient condition and a low suction pressure
Low superheat

12. Which of the following can cause excessive subcooling...
Technician B
The superheat increases and the subcooling decreases
Flooding the condenser - cycling condenser fans - and dampering condenser air
An overcharged system

13. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Lack of airflow
Whenever necessary
A low refrigerant charge

14. What causes the automatic expansion valve to close...
An increase in low-side pressure
Both technicians are correct
50-65
An undercharged system+insufficient airflow over the evaporator coil

15. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
The internal overload is opened
High suction pressure and low superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Contains a solenoid coil and one or more sets of contacts

16. Which of the following will cause excessive discharge pressures on an air conditioning system...
Broken rings+broken valves+seized bearings
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The sight glass is full of liquid+the sight glass is full of gas

17. A liquid-charged TXV bulb will...
Evaporator and compressor
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
Technician A is correct

18. Which of the following is a common cause of an excessively low superheat on a TXV system...
A restricted metering device
A sensing bulb improperly connected to the suction line
3 psig
The low-side pressure will decrease and the evaporator coil will be partially frosted

19. Superheat is found in an air conditioning system in the...
Current in the compressor circuit
An undercharge and low ambient conditions
Evaporator and compressor
The sensing bulb at a lower temperature than the valve body

20. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Clean the condenser coil
Lack of airflow
110-120
An overcharged system

21. A hard-start kit for an air conditioning system...
Low discharge pressure - high suction pressure - and low amp draw
The oil pump pressure and the crankcase pressure
Increases starting torque
Technician B

22. The temperature range of the suction line from an air conditioning system should be...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A low refrigerant charge
50-65
Whenever necessary

23. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Technician B
It keeps a constant superheat in the evaporator
Lack of airflow
Technician B

24. 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
The discharge pressure increases and the amperage increases
Low superheat
Bad compressor valve
Both technicians are incorrect

25. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
An undercharge and low ambient conditions
Technician A is correct
('Y' and 'C') and ('G' and 'C')
Bad compressor valve

26. What component is most often the cause of a start capacitor failure...
Clean the condenser coil
A start relay
Increases starting torque
Evaporator and compressor

27. 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 undercharge and low ambient conditions
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Broken rings+broken valves+seized bearings
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

28. What is the purpose of a CPR valve...
Technician B
110-120
It is used to control refrigerant pressure in the compressor crankcase
Both technicians are incorrect

29. The temperature range of the suction line from an air conditioning system should be...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An increase of air leakage from ductwork
The superheat will increase and the low-side pressure will decrease
50-65

30. A commercial customer calls on a 90
An undercharge and low ambient conditions
The system has been overcharged+The system has air trapped in the condenser
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A start capacitor and a solid-state relay

31. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Technician B
Lack of airflow
Increases starting torque
110-120

32. 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
Current in the compressor circuit
Technician B
The system has been overcharged+The system has air trapped in the condenser
Low superheat

33. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
An increase in low-side pressure
'G' to 'C'
It would cause the low-side pressure to decrease
Both technicians are incorrect

34. 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 sensing bulb at a lower temperature than the valve body
110-120
Technician A is correct
Partially frosted evaporator and high superheat

35. 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 sight glass is full of liquid+the sight glass is full of gas
Technician A
Clean the condenser coil
The discharge pressure increases and the amperage increases

36. 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 blown fuse
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
An acid-core suction line drier

37. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Broken rings+broken valves+seized bearings
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A plugged filter drier
An undercharge and low ambient conditions

38. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An uninsulated TXV sensing bulb
A blown fuse
Condenser fans operating during a low ambient condition and a low suction pressure
A missing air filter+improper rotation of the indoor blower+blower too small

39. What are two problems that can cause an air conditioning system to have an excessively high superheat...
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
110-120

40. 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 A
Increases starting torque
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician A is correct

41. 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
Bad compressor valve
A defective circuit breaker
50-65
Technician B

42. What problem or problems can cause low discharge and suction pressure...
Short cycling and insufficient dehumidification
110-120
An undercharged system+insufficient airflow over the evaporator coil
An overcharged system

43. 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
The superheat increases and the subcooling decreases
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Both technicians are incorrect
Technician B

44. 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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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...
An overcharged system
High superheat and low discharge pressure
Technician A is correct
The superheat increases and the subcooling decreases

46. Which of the following could be the cause for a system's discharge and suction pressure being low...
110-120
The sight glass is full of liquid+the sight glass is full of gas
A start relay
A restricted metering device

47. 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
110-120
A plugged filter drier
Lack of airflow

48. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
3 psig
A plugged filter drier
An uninsulated TXV sensing bulb

49. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
Technician A
The system has been overcharged+The system has air trapped in the condenser
High suction pressure and low superheat

50. 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 missing air filter+improper rotation of the indoor blower+blower too small
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The external equalizer could be plugged
An acid-core suction line drier