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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. Air filters should be replaced...
Whenever necessary
Both technicians are incorrect
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It keeps a constant superheat in the evaporator

2. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Run with high head and high suction pressure
A restricted metering device
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

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...
A restricted metering device
The sight glass is full of liquid+the sight glass is full of gas
Low voltage and a faulty start relay
An increase in low-side pressure

4. What are common methods that are used for leak-testing a system...
The sensing bulb at a lower temperature than the valve body
The low-side pressure will decrease and the evaporator coil will be partially frosted
A vacuum test+oil traces around fittings+soap bubble solution
3 psig

5. When using a vapor-charged TXV bulb - it is necessary to have...
An uninsulated TXV sensing bulb
Technician B
The sensing bulb at a lower temperature than the valve body
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

6. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
The system has been overcharged+The system has air trapped in the condenser
An undercharge and low ambient conditions
High suction pressure and low superheat
The discharge pressure increases and the amperage increases

7. What causes the automatic expansion valve to close...
Technician B
An increase in low-side pressure
Contains a solenoid coil and one or more sets of contacts
An uninsulated TXV sensing bulb

8. A restricted air filter in an air conditioning system can be identified by...
A missing air filter+improper rotation of the indoor blower+blower too small
Evaporator and compressor
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Low superheat

9. What are common methods that are used for leak-testing a system...
Technician A
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A vacuum test+oil traces around fittings+soap bubble solution
Increases starting torque

10. 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
Whenever necessary
A restricted metering device
Technician A is correct
50-65

11. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Technician B
Run with high head and high suction pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

12. A commercial customer calls on a 90
A low refrigerant charge
'G' to 'C'
Short cycling and insufficient dehumidification
The system has been overcharged+The system has air trapped in the condenser

13. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A start relay
The superheat increases and the subcooling decreases
A bad thermostat
Low discharge pressure - high suction pressure - and low amp draw

14. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A missing air filter+improper rotation of the indoor blower+blower too small
The sensing bulb at a lower temperature than the valve body
A defective circuit breaker

15. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
'G' to 'C'
20 to 30
The superheat increases and the subcooling decreases

16. 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...
Contains a solenoid coil and one or more sets of contacts
Condenser fans operating during a low ambient condition and a low suction pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

17. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
High suction pressure and low superheat
Technician A
Always have some liquid present in the bulb and diaphragm

18. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
The discharge pressure increases and the amperage increases
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B

19. The temperature range of the suction line from an air conditioning system should be...
A low refrigerant charge
50-65
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A restricted metering device

20. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A vacuum test+oil traces around fittings+soap bubble solution
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

21. 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 air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A start relay
High suction pressure and low superheat

22. 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...
Clean the condenser coil
Condenser fans operating during a low ambient condition and a low suction pressure
Both technicians are incorrect
Technician B

23. 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 increase in suction pressure and an increase in discharge pressure
20 to 30
Technician B
An undercharge and low ambient conditions

24. What is the purpose of the TXV...
An overcharged system
A low refrigerant charge
Technician B
It keeps a constant superheat in the evaporator

25. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Both technicians are incorrect
An uninsulated TXV sensing bulb
Bad compressor valve

26. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
Both technicians are correct
A low refrigerant charge
An undercharge and low ambient conditions

27. 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
A missing air filter+improper rotation of the indoor blower+blower too small
Technician A is correct
An undercharge and low ambient conditions
Both technicians are correct

28. 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...
The external equalizer could be plugged
Whenever necessary
'G' to 'C'
Low voltage and a faulty start relay

29. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician A is correct
The system has been overcharged+The system has air trapped in the condenser

30. 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
A vacuum test+oil traces around fittings+soap bubble solution
Condenser fans operating during a low ambient condition and a low suction pressure
'G' to 'C'

31. Which of the following is a common cause of an excessively low superheat on a TXV system...
A sensing bulb improperly connected to the suction line
It keeps a constant superheat in the evaporator
An overcharged system
An acid-core suction line drier

32. What is the purpose of a CPR valve...
Technician B
It is used to control refrigerant pressure in the compressor crankcase
Contains a solenoid coil and one or more sets of contacts
An increase in suction pressure and an increase in discharge pressure

33. What component is most often the cause of a start capacitor failure...
An overcharged system
A start relay
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

34. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
A dirty condenser - recirculation of condenser air - and a defective condenser fan
('Y' and 'C') and ('G' and 'C')
An uninsulated suction line and a restricted metering device

35. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A low refrigerant charge
It would cause the low-side pressure to decrease
A plugged filter drier
The sight glass is full of liquid+the sight glass is full of gas

36. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
The low-side pressure will decrease and the evaporator coil will be partially frosted
An overcharged system
Current in the compressor circuit
High suction pressure and low superheat

37. Insufficient airflow can be caused by...
The sensing bulb at a lower temperature than the valve body
Both technicians are incorrect
Condenser fans operating during a low ambient condition and a low suction pressure
An increase of air leakage from ductwork

38. Which of the following is a common cause of an excessively low superheat on a TXV system...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A sensing bulb improperly connected to the suction line
The oil pump pressure and the crankcase pressure
An overcharged system

39. Superheat is found in an air conditioning system in the...
Evaporator and compressor
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B
An open internal overload protector

40. 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
3 psig
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician A

41. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
It keeps a constant superheat in the evaporator
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A start relay

42. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An overcharged system
A vacuum test+oil traces around fittings+soap bubble solution
An undercharge and low ambient conditions
Technician B

43. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician B
The internal overload is opened
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

44. The internal overload of an air conditioning compressor senses winding temperature and...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
'G' to 'C'
Current in the compressor circuit
The system has been overcharged+The system has air trapped in the condenser

45. What are the operating pressures of an oil pressure safety switch...
Rise more than normal
The oil pump pressure and the crankcase pressure
It would cause the low-side pressure to decrease
A missing air filter+improper rotation of the indoor blower+blower too small

46. 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
Run with high head and high suction pressure
An undercharge and low ambient conditions
Low voltage and a faulty start relay
Technician B

47. 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
An increase of air leakage from ductwork
Broken rings+broken valves+seized bearings
The sight glass is full of liquid+the sight glass is full of gas
A low refrigerant charge

48. 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
Evaporator and compressor
A bad thermostat
Both technicians are incorrect
Partially frosted evaporator and high superheat

49. 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
The sight glass is full of liquid+the sight glass is full of gas
A bad thermostat
Technician B

50. 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
Both technicians are correct
Technician B
Contains a solenoid coil and one or more sets of contacts
Technician B