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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. The internal overload of an air conditioning compressor senses winding temperature and...
A plugged filter drier
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Current in the compressor circuit
Both technicians are incorrect

2. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
The superheat will increase and the low-side pressure will decrease
Run with high head and high suction pressure
110-120

3. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
20 to 30

4. 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 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
Condenser fans operating during a low ambient condition and a low suction pressure
The internal overload is opened

5. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Both technicians are incorrect
Contains a solenoid coil and one or more sets of contacts

6. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
3 psig
It keeps a constant superheat in the evaporator
Lack of airflow
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

7. The temperature range of the suction line from an air conditioning system should be...
Run with high head and high suction pressure
A start capacitor and a solid-state relay
The discharge pressure increases and the amperage increases
50-65

8. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A restricted metering device

9. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
Current in the compressor circuit
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

10. Insufficient airflow can be caused by...
Both technicians are incorrect
The external equalizer could be plugged
An increase of air leakage from ductwork
Short cycling and insufficient dehumidification

11. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
The superheat increases and the subcooling decreases
An open internal overload protector
Technician A is correct

12. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The sensing bulb at a lower temperature than the valve body
3 psig
It keeps a constant superheat in the evaporator
The superheat increases and the subcooling decreases

13. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
('Y' and 'C') and ('G' and 'C')
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Both technicians are incorrect
An increase of air leakage from ductwork

14. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
Run with high head and high suction pressure
A bad thermostat
Current in the compressor circuit

15. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

16. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Both technicians are incorrect
It is used to control refrigerant pressure in the compressor crankcase
High suction pressure and low superheat
A low refrigerant charge

17. A customer calls with an insufficient cooling complaint on a 90
The low-side pressure will decrease and the evaporator coil will be partially frosted
An open internal overload protector
A start relay
Technician B

18. 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 superheat will increase and the low-side pressure will decrease
Broken rings+broken valves+seized bearings
Technician A is correct
Dirty condenser - bent condenser fins - and air recirculating over the condenser

19. Which of the following can cause excessive subcooling...
A start relay
Technician A is correct
An overcharged system
A restricted metering device

20. A hard-start kit consists of...
Both technicians are incorrect
Low discharge pressure - high suction pressure - and low amp draw
A start capacitor and a solid-state relay
An increase of air leakage from ductwork

21. What are two common symptoms of refrigerant leaks in an air conditioning system...
High suction pressure and low superheat
Always have some liquid present in the bulb and diaphragm
Partially frosted evaporator and high superheat
Technician B

22. What problem or problems can cause low discharge and suction pressure...
Both technicians are correct
Rise more than normal
An undercharged system+insufficient airflow over the evaporator coil
An undercharge and low ambient conditions

23. Which of the following is a common cause of an excessively low superheat on a TXV system...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Clean the condenser coil
Technician B
A sensing bulb improperly connected to the suction line

24. 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
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician A
A sensing bulb improperly connected to the suction line

25. 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
Low superheat
Technician B
Rise more than normal
An increase in low-side pressure

26. What are common methods that are used for leak-testing a system...
Low discharge pressure - high suction pressure - and low amp draw
Condenser fans operating during a low ambient condition and a low suction pressure
A vacuum test+oil traces around fittings+soap bubble solution
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

27. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
Run with high head and high suction pressure
Both technicians are incorrect
110-120

28. 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
The oil pump pressure and the crankcase pressure
Both technicians are incorrect
Both technicians are correct
An overcharged system

29. What are the operating pressures of an oil pressure safety switch...
An increase in low-side pressure
Whenever necessary
The oil pump pressure and the crankcase pressure
Low discharge pressure - high suction pressure - and low amp draw

30. 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
Bad compressor valve
A plugged filter drier
An increase in low-side pressure
Technician B

31. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
The superheat increases and the subcooling decreases
An undercharge and low ambient conditions
Low superheat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

32. 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
The sight glass is full of liquid+the sight glass is full of gas
Technician A
An acid-core suction line drier
Technician B

33. A customer calls with an insufficient cooling complaint on a 90
An uninsulated TXV sensing bulb
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
Bad compressor valve

34. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
It keeps a constant superheat in the evaporator
A vacuum test+oil traces around fittings+soap bubble solution
The oil pump pressure and the crankcase pressure

35. What component is most often the cause of a start capacitor failure...
Technician B
A start relay
Technician B
The sensing bulb at a lower temperature than the valve body

36. 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
Both technicians are correct
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A blown fuse
A defective circuit breaker

37. What are two common symptoms of refrigerant leaks in an air conditioning system...
It is used to control refrigerant pressure in the compressor crankcase
An overcharged system
Partially frosted evaporator and high superheat
110-120

38. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
A start capacitor and a solid-state relay
Low discharge pressure - high suction pressure - and low amp draw
Technician B

39. Which of the following is a possible cause for a compressor to overheat...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
It would cause the low-side pressure to decrease
A low refrigerant charge
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

40. A commercial customer calls on a 90
A low refrigerant charge
A bad thermostat
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

41. Why is it unsafe to operate an air conditioning system with a low charge...
It would cause the low-side pressure to decrease
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The sight glass is full of liquid+the sight glass is full of gas
The oil pump pressure and the crankcase pressure

42. What are the symptoms of an air conditioning system that has a low charge...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A start capacitor and a solid-state relay
An overcharged system
The superheat will increase and the low-side pressure will decrease

43. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
The superheat will increase and the low-side pressure will decrease
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A plugged filter drier

44. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Technician A is correct
An undercharge and low ambient conditions
Evaporator and compressor
A start capacitor and a solid-state relay

45. 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
Technician A
Increases starting torque
An increase of air leakage from ductwork
Technician B

46. Air filters should be replaced...
Technician B
Technician B
Whenever necessary
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

47. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
The sensing bulb at a lower temperature than the valve body
Clean the condenser coil
A bad thermostat

48. What causes the automatic expansion valve to close...
High suction pressure and low superheat
An increase in low-side pressure
An uninsulated TXV sensing bulb
The discharge pressure increases and the amperage increases

49. 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 defective circuit breaker
Partially frosted evaporator and high superheat
It would cause the low-side pressure to decrease

50. 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
Lack of airflow
Technician A
Bad compressor valve
Rise more than normal