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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. Superheat is found in an air conditioning system in the...
The superheat will increase and the low-side pressure will decrease
Evaporator and compressor
A plugged filter drier
Rise more than normal

2. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
It is used to control refrigerant pressure in the compressor crankcase
Technician B
An uninsulated suction line and a restricted metering device

3. 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
A start relay
The sensing bulb at a lower temperature than the valve body
An increase in suction pressure and an increase in discharge pressure
Technician B

4. 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
An acid-core suction line drier
It would cause the low-side pressure to decrease
Evaporator and compressor
Both technicians are incorrect

5. What is the purpose of the TXV...
A sensing bulb improperly connected to the suction line
Condenser fans operating during a low ambient condition and a low suction pressure
An increase in suction pressure and an increase in discharge pressure
It keeps a constant superheat in the evaporator

6. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
High suction pressure and low superheat

7. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The system has been overcharged+The system has air trapped in the condenser
Always have some liquid present in the bulb and diaphragm

8. A system that uses a thermal electric expansion valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Run with high head and high suction pressure
Low voltage and a faulty start relay
High superheat and low discharge pressure

9. What problem or problems can cause low discharge and suction pressure...
A low refrigerant charge
An undercharged system+insufficient airflow over the evaporator coil
Current in the compressor circuit
The external equalizer could be plugged

10. The internal overload of an air conditioning compressor senses winding temperature and...
The sight glass is full of liquid+the sight glass is full of gas
A sensing bulb improperly connected to the suction line
Current in the compressor circuit
A bad thermostat

11. Technician A says ' When charging a system using the superheat method - adding refrigerant to the system will increase the superheat.' Technician B says 'When charging a system using the superheat method - adding refrigerant will decrease the superhe
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Low superheat
Bad compressor valve

12. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
It would cause the low-side pressure to decrease
The sensing bulb at a lower temperature than the valve body
The superheat increases and the subcooling decreases

13. What component is most often the cause of a start capacitor failure...
A start relay
An increase in suction pressure and an increase in discharge pressure
Both technicians are incorrect
It is used to control refrigerant pressure in the compressor crankcase

14. 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
Technician B
An open internal overload protector
A vacuum test+oil traces around fittings+soap bubble solution
Condenser fans operating during a low ambient condition and a low suction pressure

15. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An acid-core suction line drier
The discharge pressure increases and the amperage increases
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The superheat increases and the subcooling decreases

16. A technician receives an air conditioning service call stating that the system is operating but isn't cooling properly. When the technician arrives - she notices that the compressor has recently been changed and it is an are-22 system. She checks the
Low discharge pressure - high suction pressure - and low amp draw
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are incorrect
A plugged filter drier

17. Which of the following will cause excessive discharge pressures on 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
Bad compressor valve
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are incorrect

18. A compressor having tight bearings would cause the current value to...
A start capacitor and a solid-state relay
A missing air filter+improper rotation of the indoor blower+blower too small
An open internal overload protector
Rise more than normal

19. A system that is operating with a clear sight glass shows...
Both technicians are incorrect
Rise more than normal
A start capacitor and a solid-state relay
The sight glass is full of liquid+the sight glass is full of gas

20. 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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21. 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 increases and the subcooling decreases
A bad thermostat
It is used to control refrigerant pressure in the compressor crankcase

22. 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
Condenser fans operating during a low ambient condition and a low suction pressure
Both technicians are incorrect
'G' to 'C'
A bad thermostat

23. What type of problems can be caused by an oversized air conditioning system...
110-120
Low superheat
Short cycling and insufficient dehumidification
Technician B

24. 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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
Technician A

25. When using a vapor-charged TXV bulb - it is necessary to have...
An undercharge and low ambient conditions
Partially frosted evaporator and high superheat
The sensing bulb at a lower temperature than the valve body
An increase in suction pressure and an increase in discharge pressure

26. 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
A blown fuse
An increase of air leakage from ductwork
Broken rings+broken valves+seized bearings
Dirty condenser - bent condenser fins - and air recirculating over the condenser

27. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
'G' to 'C'
An undercharged system+insufficient airflow over the evaporator coil
High suction pressure and low superheat
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

28. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
110-120
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Condenser fans operating during a low ambient condition and a low suction pressure

29. 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 defective circuit breaker
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Low voltage and a faulty start relay
A missing air filter+improper rotation of the indoor blower+blower too small

30. 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
Increases starting torque
A bad thermostat
Both technicians are correct
20 to 30

31. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in suction pressure and an increase in discharge pressure
Lack of airflow

32. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
The external equalizer could be plugged
Both technicians are incorrect
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

33. The internal overload of an air conditioning compressor senses winding temperature and...
Technician B
Current in the compressor circuit
Always have some liquid present in the bulb and diaphragm
Technician B

34. A compressor having tight bearings would cause the current value to...
The internal overload is opened
A sensing bulb improperly connected to the suction line
Technician B
Rise more than normal

35. 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
Always have some liquid present in the bulb and diaphragm
A low refrigerant charge
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 correct

36. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
Technician B
Run with high head and high suction pressure
An overcharged system

37. A hard-start kit consists of...
An acid-core suction line drier
A start capacitor and a solid-state relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It keeps a constant superheat in the evaporator

38. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
The sight glass is full of liquid+the sight glass is full of gas
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

39. Air filters should be replaced...
Whenever necessary
A restricted metering device
Technician B
Lack of airflow

40. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
An overcharged system
The low-side pressure will decrease and the evaporator coil will be partially frosted
Low voltage and a faulty start relay
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

41. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Technician B
Clean the condenser coil
Bad compressor valve
The superheat increases and the subcooling decreases

42. Why is it unsafe to operate an air conditioning system with a low charge...
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
Low voltage and a faulty start relay
The sight glass is full of liquid+the sight glass is full of gas

43. Air filters should be replaced...
A defective circuit breaker
An uninsulated suction line and a restricted metering device
Whenever necessary
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

44. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Broken rings+broken valves+seized bearings
Low discharge pressure - high suction pressure - and low amp draw
Technician B
A vacuum test+oil traces around fittings+soap bubble solution

45. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Whenever necessary
An overcharged system
A missing air filter+improper rotation of the indoor blower+blower too small
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

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
Both technicians are incorrect
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
Both technicians are correct

47. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
A bad thermostat

48. A customer calls with an insufficient cooling complaint on a 90
Whenever necessary
Technician B
'G' to 'C'
('Y' and 'C') and ('G' and 'C')

49. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A defective circuit breaker
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Partially frosted evaporator and high superheat
Rise more than normal

50. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A plugged filter drier
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure