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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 problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
50-65
Technician B
The discharge pressure increases and the amperage increases
Bad compressor valve

2. What are the symptoms of an air conditioning system that has a low charge...
Condenser fans operating during a low ambient condition and a low suction pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
A start capacitor and a solid-state relay
An open internal overload protector

3. 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...
Clean the condenser coil
Technician A
The internal overload is opened
Low voltage and a faulty start relay

4. What type of problems can be caused by an oversized air conditioning system...
Partially frosted evaporator and high superheat
A sensing bulb improperly connected to the suction line
High superheat and low discharge pressure
Short cycling and insufficient dehumidification

5. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Technician B
A plugged filter drier
Always have some liquid present in the bulb and diaphragm
The low-side pressure will decrease and the evaporator coil will be partially frosted

6. Air filters should be replaced...
Technician B
Whenever necessary
An overcharged system
20 to 30

7. What causes the automatic expansion valve to close...
Evaporator and compressor
Both technicians are incorrect
An increase in low-side pressure
Lack of airflow

8. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
High suction pressure and low superheat
Run with high head and high suction pressure
The discharge pressure increases and the amperage increases
An overcharged system

9. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
Low superheat
Condenser fans operating during a low ambient condition and a low suction pressure
A bad thermostat

10. What are the symptoms of a TXV air conditioning system if it has lost its charge...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An uninsulated TXV sensing bulb
The superheat will increase and the low-side pressure will decrease
The discharge pressure increases and the amperage increases

11. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
An undercharge and low ambient conditions
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
20 to 30
Technician B

12. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician A is correct
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
('Y' and 'C') and ('G' and 'C')

13. A customer calls with an insufficient cooling complaint on a 90
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
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

14. 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
An increase in low-side pressure
Technician B
An increase in low-side pressure
The internal overload is opened

15. Air filters should be replaced...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Whenever necessary
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A restricted metering device

16. The temperature range of the suction line from an air conditioning system should be...
An uninsulated suction line and a restricted metering device
Technician B
50-65
A missing air filter+improper rotation of the indoor blower+blower too small

17. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Technician B
The discharge pressure increases and the amperage increases
Both technicians are incorrect
The oil pump pressure and the crankcase pressure

18. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Technician A is correct
It would cause the low-side pressure to decrease
It keeps a constant superheat in the evaporator
A missing air filter+improper rotation of the indoor blower+blower too small

19. 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 sensing bulb at a lower temperature than the valve body
An undercharged system+insufficient airflow over the evaporator coil
An increase in suction pressure and an increase in discharge pressure
Technician B

20. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Always have some liquid present in the bulb and diaphragm
Technician B
Broken rings+broken valves+seized bearings
It would cause the low-side pressure to decrease

21. A commercial customer calls on a 90
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The system has been overcharged+The system has air trapped in the condenser
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
High superheat and low discharge pressure

22. 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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23. A hard-start kit consists of...
An overcharged system
A blown fuse
A start capacitor and a solid-state relay
Bad compressor valve

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
An increase of air leakage from ductwork
The oil pump pressure and the crankcase pressure
Clean the condenser coil
Short cycling and insufficient dehumidification

25. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
An overcharged system
A bad thermostat
Low voltage and a faulty start relay

26. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Both technicians are correct
An acid-core suction line drier
Whenever necessary
Low discharge pressure - high suction pressure - and low amp draw

27. 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
Technician B
Whenever necessary
The superheat will increase and the low-side pressure will decrease

28. Why is it unsafe to operate an air conditioning system with a low charge...
An undercharged system+insufficient airflow over the evaporator coil
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A vacuum test+oil traces around fittings+soap bubble solution
Broken rings+broken valves+seized bearings

29. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
It is used to control refrigerant pressure in the compressor crankcase
The sight glass is full of liquid+the sight glass is full of gas
('Y' and 'C') and ('G' and 'C')

30. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Evaporator and compressor
The sight glass is full of liquid+the sight glass is full of gas

31. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
An uninsulated TXV sensing bulb
50-65
Technician A
Technician B

32. 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 system has been overcharged+The system has air trapped in the condenser
The sensing bulb at a lower temperature than the valve body
Technician A
50-65

33. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
50-65
A sensing bulb improperly connected to the suction line
Whenever necessary
An undercharge and low ambient conditions

34. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Short cycling and insufficient dehumidification
The superheat will increase and the low-side pressure will decrease
The discharge pressure increases and the amperage increases
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

35. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
An acid-core suction line drier
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An uninsulated TXV sensing bulb

36. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
An uninsulated TXV sensing bulb
An acid-core suction line drier
An uninsulated TXV sensing bulb

37. When using a vapor-charged TXV bulb - it is necessary to have...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The sensing bulb at a lower temperature than the valve body
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An uninsulated TXV sensing bulb

38. 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
Lack of airflow
A defective circuit breaker
Contains a solenoid coil and one or more sets of contacts
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

39. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A start relay
3 psig

40. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
It would cause the low-side pressure to decrease
110-120
An open internal overload protector
An undercharged system+insufficient airflow over the evaporator coil

41. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Rise more than normal
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Low discharge pressure - high suction pressure - and low amp draw
Flooding the condenser - cycling condenser fans - and dampering condenser air

42. A liquid-charged TXV bulb will...
The low-side pressure will decrease and the evaporator coil will be partially frosted
It is used to control refrigerant pressure in the compressor crankcase
Always have some liquid present in the bulb and diaphragm
20 to 30

43. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Both technicians are incorrect
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Partially frosted evaporator and high superheat
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

44. 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
Evaporator and compressor
Run with high head and high suction pressure
An acid-core suction line drier

45. 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
An increase in low-side pressure
High suction pressure and low superheat
The external equalizer could be plugged
Increases starting torque

46. 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 undercharged system+insufficient airflow over the evaporator coil
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An acid-core suction line drier

47. A compressor having tight bearings would cause the current value to...
20 to 30
An overcharged system
Rise more than normal
Technician B

48. What component is most often the cause of a start capacitor failure...
Both technicians are correct
Increases starting torque
'G' to 'C'
A start relay

49. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
110-120
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
3 psig
Current in the compressor circuit

50. 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...
The internal overload is opened
An undercharge and low ambient conditions
Low voltage and a faulty start relay
Rise more than normal