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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 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 is used to control refrigerant pressure in the compressor crankcase
Current in the compressor circuit
Technician B
A start capacitor and a solid-state relay

2. Why is it unsafe to operate an air conditioning system with a low charge...
Flooding the condenser - cycling condenser fans - and dampering condenser air
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Bad compressor valve
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

3. The temperature range of the suction line from an air conditioning system should be...
50-65
The sensing bulb at a lower temperature than the valve body
Current in the compressor circuit
Whenever necessary

4. A hard-start kit for an air conditioning system...
Partially frosted evaporator and high superheat
The sight glass is full of liquid+the sight glass is full of gas
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Increases starting torque

5. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Increases starting torque
Technician A is correct
Flooding the condenser - cycling condenser fans - and dampering condenser air
An overcharged system

6. A system that uses a thermal electric expansion valve...
A restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A blown fuse
An undercharge and low ambient conditions

7. 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
An overcharged system
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

8. Air filters should be replaced...
Lack of airflow
Low superheat
Whenever necessary
Both technicians are incorrect

9. 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
50-65
Technician B
Technician B

10. Which of the following will cause excessive discharge pressures on an air conditioning system...
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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A bad thermostat

11. 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
Clean the condenser coil
The superheat increases and the subcooling decreases
Whenever necessary
Broken rings+broken valves+seized bearings

12. 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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13. Air filters should be replaced...
Whenever necessary
A low refrigerant charge
An undercharge and low ambient conditions
A missing air filter+improper rotation of the indoor blower+blower too small

14. 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 evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It would cause the low-side pressure to decrease
High superheat and low discharge pressure
Both technicians are incorrect

15. What are common methods that are used for leak-testing a system...
110-120
Technician B
High suction pressure and low superheat
A vacuum test+oil traces around fittings+soap bubble solution

16. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
High suction pressure and low superheat
Partially frosted evaporator and high superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted

17. 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...
Low voltage and a faulty start relay
Technician B
Increases starting torque
It would cause the low-side pressure to decrease

18. What are common methods that are used for leak-testing a system...
Technician B
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
High superheat and low discharge pressure

19. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
Both technicians are incorrect
The low-side pressure will decrease and the evaporator coil will be partially frosted
110-120

20. What problem or problems can cause low discharge and suction pressure...
Low voltage and a faulty start relay
An undercharged system+insufficient airflow over the evaporator coil
The external equalizer could be plugged
High suction pressure and low superheat

21. Superheat is found in an air conditioning system in the...
Bad compressor valve
Evaporator and compressor
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted

22. What problem or problems can cause low discharge and suction pressure...
It is used to control refrigerant pressure in the compressor crankcase
It would cause the low-side pressure to decrease
Technician A is correct
An undercharged system+insufficient airflow over the evaporator coil

23. Which of the following can cause low superheat in a TXV system...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
20 to 30
An uninsulated TXV sensing bulb
An undercharged system+insufficient airflow over the evaporator coil

24. 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
An uninsulated suction line and a restricted metering device
Bad compressor valve
Technician B
Low voltage and a faulty start relay

25. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Technician B
An uninsulated suction line and a restricted metering device
A start relay
A missing air filter+improper rotation of the indoor blower+blower too small

26. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
An increase of air leakage from ductwork
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A bad thermostat

27. 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 B
Technician A is correct
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A sensing bulb improperly connected to the suction line

28. 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
Low discharge pressure - high suction pressure - and low amp draw
An open internal overload protector
Technician B
Technician B

29. Which of the following could be the cause for a system's discharge and suction pressure being low...
The external equalizer could be plugged
('Y' and 'C') and ('G' and 'C')
A restricted metering device
The internal overload is opened

30. 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
Short cycling and insufficient dehumidification
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
'G' to 'C'

31. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It would cause the low-side pressure to decrease
Run with high head and high suction pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

32. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The superheat will increase and the low-side pressure will decrease
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The superheat will increase and the low-side pressure will decrease

33. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An undercharge and low ambient conditions
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
Technician B

34. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A start capacitor and a solid-state relay
Condenser fans operating during a low ambient condition and a low suction pressure

35. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
An uninsulated TXV sensing bulb
High superheat and low discharge pressure
Short cycling and insufficient dehumidification

36. What are two common symptoms of refrigerant leaks in an air conditioning system...
The sensing bulb at a lower temperature than the valve body
'G' to 'C'
Partially frosted evaporator and high superheat
Technician B

37. 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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38. Insufficient airflow can be caused by...
Technician B
Technician B
The sight glass is full of liquid+the sight glass is full of gas
An increase of air leakage from ductwork

39. 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...
Low voltage and a faulty start relay
Both technicians are correct
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B

40. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Low discharge pressure - high suction pressure - and low amp draw
A start relay
It would cause the low-side pressure to decrease
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

41. Superheat is found in an air conditioning system in the...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Evaporator and compressor
Technician B
An acid-core suction line drier

42. What causes the automatic expansion valve to close...
A blown fuse
An increase in low-side pressure
A bad thermostat
Broken rings+broken valves+seized bearings

43. 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
A sensing bulb improperly connected to the suction line
Clean the condenser coil
The discharge pressure increases and the amperage increases

44. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
3 psig
Technician B
A start capacitor and a solid-state relay

45. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
Technician B
An increase in low-side pressure
The superheat will increase and the low-side pressure will decrease

46. 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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47. The internal overload of an air conditioning compressor senses winding temperature and...
An undercharge and low ambient conditions
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Evaporator and compressor
Current in the compressor circuit

48. 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
Both technicians are incorrect
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An increase in suction pressure and an increase in discharge pressure
Clean the condenser coil

49. When using a vapor-charged TXV bulb - it is necessary to have...
110-120
The sensing bulb at a lower temperature than the valve body
An uninsulated TXV sensing bulb
20 to 30

50. The internal overload of an air conditioning compressor senses winding temperature and...
An increase in low-side pressure
Partially frosted evaporator and high superheat
Technician A
Current in the compressor circuit