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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 is the purpose of a CPR valve...
An undercharged system+insufficient airflow over the evaporator coil
Technician B
It is used to control refrigerant pressure in the compressor crankcase
Whenever necessary

2. 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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3. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
An acid-core suction line drier
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Short cycling and insufficient dehumidification

4. What type of problems can be caused by an oversized air conditioning system...
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
The superheat will increase and the low-side pressure will decrease
Short cycling and insufficient dehumidification

5. What three things can prevent an air conditioning system from releasing heat at the proper rate...
An overcharged system
An increase of air leakage from ductwork
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A dirty condenser - recirculation of condenser air - and a defective condenser fan

6. 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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7. What problem can cause an increase of discharge pressure and an increase of suction pressure...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
('Y' and 'C') and ('G' and 'C')
The internal overload is opened
An overcharged system

8. 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...
Both technicians are incorrect
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An undercharged system+insufficient airflow over the evaporator coil
Low voltage and a faulty start relay

9. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
The sight glass is full of liquid+the sight glass is full of gas
The low-side pressure will decrease and the evaporator coil will be partially frosted
The sensing bulb at a lower temperature than the valve body

10. A liquid-charged TXV bulb will...
An uninsulated suction line and a restricted metering device
Always have some liquid present in the bulb and diaphragm
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The low-side pressure will decrease and the evaporator coil will be partially frosted

11. A compressor having tight bearings would cause the current value to...
Technician B
Rise more than normal
Both technicians are incorrect
An overcharged system

12. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
An uninsulated TXV sensing bulb
Low voltage and a faulty start relay
Dirty condenser - bent condenser fins - and air recirculating over the condenser

13. What causes the automatic expansion valve to close...
An acid-core suction line drier
An increase in low-side pressure
The superheat increases and the subcooling decreases
The superheat will increase and the low-side pressure will decrease

14. What are two common symptoms of refrigerant leaks in an air conditioning system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Flooding the condenser - cycling condenser fans - and dampering condenser air
Increases starting torque
Partially frosted evaporator and high superheat

15. 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
Both technicians are incorrect
The superheat increases and the subcooling decreases
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A bad thermostat

16. A system that uses a thermal electric expansion valve...
It is used to control refrigerant pressure in the compressor crankcase
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The sight glass is full of liquid+the sight glass is full of gas

17. What problem or problems can cause low discharge and suction pressure...
Rise more than normal
An undercharged system+insufficient airflow over the evaporator coil
Condenser fans operating during a low ambient condition and a low suction pressure
An overcharged system

18. The temperature range of the suction line from an air conditioning system should be...
50-65
An undercharged system+insufficient airflow over the evaporator coil
A restricted metering device
Technician B

19. 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
Whenever necessary
Condenser fans operating during a low ambient condition and a low suction pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

20. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
It is used to control refrigerant pressure in the compressor crankcase
Both technicians are correct
The sensing bulb at a lower temperature than the valve body

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 defective circuit breaker
Current in the compressor circuit
Condenser fans operating during a low ambient condition and a low suction pressure
The oil pump pressure and the crankcase pressure

22. 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 start relay
An open internal overload protector
A plugged filter drier
Broken rings+broken valves+seized bearings

23. 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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24. What problem or problems can cause low discharge and suction pressure...
It is used to control refrigerant pressure in the compressor crankcase
An overcharged system
An undercharged system+insufficient airflow over the evaporator coil
Technician B

25. A hard-start kit consists of...
It is used to control refrigerant pressure in the compressor crankcase
A start capacitor and a solid-state relay
An overcharged system
A missing air filter+improper rotation of the indoor blower+blower too small

26. 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
It keeps a constant superheat in the evaporator
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
Low superheat

27. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An uninsulated suction line and a restricted metering device
A blown fuse

28. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase in suction pressure and an increase in discharge pressure
Technician B

29. 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 fans operating during a low ambient condition and a low suction pressure
The superheat will increase and the low-side pressure will decrease
High suction pressure and low superheat

30. 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
20 to 30
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The external equalizer could be plugged
Clean the condenser coil

31. A customer calls with an insufficient cooling complaint on a 90
3 psig
Technician B
Both technicians are incorrect
Current in the compressor circuit

32. A system that uses a thermal electric expansion valve...
Contains a solenoid coil and one or more sets of contacts
Lack of airflow
An uninsulated TXV sensing bulb
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

33. The best description of a relay would be...
A start relay
Both technicians are incorrect
Contains a solenoid coil and one or more sets of contacts
Condenser fans operating during a low ambient condition and a low suction pressure

34. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An increase in low-side pressure
An undercharge and low ambient conditions

35. Which of the following is a possible cause for a compressor to overheat...
Increases starting torque
A low refrigerant charge
A bad thermostat
Technician B

36. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A blown fuse
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Current in the compressor circuit
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

37. A hard-start kit for an air conditioning system...
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
The sight glass is full of liquid+the sight glass is full of gas
An overcharged system

38. 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
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
A restricted metering device
The external equalizer could be plugged

39. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A bad thermostat
20 to 30
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

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
The sensing bulb at a lower temperature than the valve body
It is used to control refrigerant pressure in the compressor crankcase
Technician A
Technician B

41. 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
Technician B
An undercharged system+insufficient airflow over the evaporator coil
It would cause the low-side pressure to decrease

42. A customer calls with an insufficient cooling complaint on a 90
The superheat will increase and the low-side pressure will decrease
A bad thermostat
Always have some liquid present in the bulb and diaphragm
Technician B

43. A liquid-charged TXV bulb will...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The system has been overcharged+The system has air trapped in the condenser
Always have some liquid present in the bulb and diaphragm
Clean the condenser coil

44. What are three methods for controlling a system's high-side pressure during low ambient conditions...
The oil pump pressure and the crankcase pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
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

45. The internal overload of an air conditioning compressor senses winding temperature and...
Technician B
Low superheat
Current in the compressor circuit
110-120

46. The technician observes that the compressor is not operating. The compressor windings read 5 ohms start to run - run to common is opened - and start to common is opened. The technician concludes that...
Broken rings+broken valves+seized bearings
Low discharge pressure - high suction pressure - and low amp draw
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The internal overload is opened

47. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Rise more than normal
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
It is used to control refrigerant pressure in the compressor crankcase
The superheat increases and the subcooling decreases

48. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
An open internal overload protector
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The superheat will increase and the low-side pressure will decrease

49. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Low discharge pressure - high suction pressure - and low amp draw
Run with high head and high suction pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A plugged filter drier

50. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
The sight glass is full of liquid+the sight glass is full of gas
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The superheat will increase and the low-side pressure will decrease