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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. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Both technicians are incorrect
('Y' and 'C') and ('G' and 'C')
An increase of air leakage from ductwork
A missing air filter+improper rotation of the indoor blower+blower too small

2. 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
'G' to 'C'
Flooding the condenser - cycling condenser fans - and dampering condenser air
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B

3. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
A low refrigerant charge
A start capacitor and a solid-state relay
The oil pump pressure and the crankcase pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

4. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
The oil pump pressure and the crankcase pressure
Technician B
A restricted metering device

5. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
3 psig
'G' to 'C'
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

6. What component is most often the cause of a start capacitor failure...
Short cycling and insufficient dehumidification
A start relay
Dirty condenser - bent condenser fins - and air recirculating over the condenser
High suction pressure and low superheat

7. Which of the following is a possible cause for a compressor to overheat...
The oil pump pressure and the crankcase pressure
An uninsulated suction line and a restricted metering device
'G' to 'C'
A low refrigerant charge

8. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The external equalizer could be plugged
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Increases starting torque

9. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician B
Technician A
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

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
The sight glass is full of liquid+the sight glass is full of gas
An open internal overload protector
Technician A is correct
50-65

11. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A bad thermostat
High suction pressure and low superheat
'G' to 'C'
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

12. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Technician A is correct
Technician B
Technician B
The superheat will increase and the low-side pressure will decrease

13. 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
110-120
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are correct
A dirty condenser - recirculation of condenser air - and a defective condenser fan

14. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

15. 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...
A restricted metering device
A defective circuit breaker
The internal overload is opened
A dirty condenser - recirculation of condenser air - and a defective condenser fan

16. 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
Both technicians are correct
Broken rings+broken valves+seized bearings
It is used to control refrigerant pressure in the compressor crankcase

17. What type of problems can be caused by an oversized air conditioning system...
An acid-core suction line drier
High suction pressure and low superheat
Evaporator and compressor
Short cycling and insufficient dehumidification

18. What is the purpose of a CPR valve...
An overcharged system
It is used to control refrigerant pressure in the compressor crankcase
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An acid-core suction line drier

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
50-65
Low voltage and a faulty start relay
An uninsulated suction line and a restricted metering device

20. 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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A bad thermostat
Technician B

21. A compressor having tight bearings would cause the current value to...
Rise more than normal
110-120
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

22. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
Condenser fans operating during a low ambient condition and a low suction pressure
Partially frosted evaporator and high superheat
Low discharge pressure - high suction pressure - and low amp draw

23. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Bad compressor valve
An uninsulated TXV sensing bulb
('Y' and 'C') and ('G' and 'C')
A missing air filter+improper rotation of the indoor blower+blower too small

24. What are the symptoms of an air conditioning system that has a low charge...
A missing air filter+improper rotation of the indoor blower+blower too small
A bad thermostat
The low-side pressure will decrease and the evaporator coil will be partially frosted
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

25. The temperature range of the suction line from an air conditioning system should be...
An open internal overload protector
It keeps a constant superheat in the evaporator
A low refrigerant charge
50-65

26. A hard-start kit consists of...
A start capacitor and a solid-state relay
An uninsulated suction line and a restricted metering device
It would cause the low-side pressure to decrease
A bad thermostat

27. What are common methods that are used for leak-testing a system...
The oil pump pressure and the crankcase pressure
An acid-core suction line drier
A vacuum test+oil traces around fittings+soap bubble solution
The oil pump pressure and the crankcase pressure

28. What problem or problems can cause low discharge and suction pressure...
An uninsulated TXV sensing bulb
Current in the compressor circuit
Technician B
An undercharged system+insufficient airflow over the evaporator coil

29. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
The sensing bulb at a lower temperature than the valve body
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The oil pump pressure and the crankcase pressure
Lack of airflow

30. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
The low-side pressure will decrease and the evaporator coil will be partially frosted
50-65
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B

31. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
Low voltage and a faulty start relay
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

32. 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
It would cause the low-side pressure to decrease
A bad thermostat
Partially frosted evaporator and high superheat
An uninsulated suction line and a restricted metering device

33. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Lack of airflow
Low discharge pressure - high suction pressure - and low amp draw
A sensing bulb improperly connected to the suction line
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

34. 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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35. What are two common symptoms of refrigerant leaks in an air conditioning system...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Run with high head and high suction pressure
An undercharge and low ambient conditions
Partially frosted evaporator and high superheat

36. What is the purpose of the TXV...
High suction pressure and low superheat
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A plugged filter drier
It keeps a constant superheat in the evaporator

37. The best description of a relay would be...
An undercharged system+insufficient airflow over the evaporator coil
Contains a solenoid coil and one or more sets of contacts
An acid-core suction line drier
50-65

38. What are the symptoms of an air conditioning system that has a low charge...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An overcharged system
The low-side pressure will decrease and the evaporator coil will be partially frosted
A low refrigerant charge

39. What are common methods that are used for leak-testing a system...
It keeps a constant superheat in the evaporator
Clean the condenser coil
A vacuum test+oil traces around fittings+soap bubble solution
The discharge pressure increases and the amperage increases

40. Which of the following can cause excessive subcooling...
Both technicians are correct
The low-side pressure will decrease and the evaporator coil will be partially frosted
An overcharged system
An undercharge and low ambient conditions

41. A restricted air filter in an air conditioning system can be identified by...
Broken rings+broken valves+seized bearings
Technician B
Increases starting torque
Low superheat

42. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
3 psig
The sensing bulb at a lower temperature than the valve body
A start relay

43. What is the purpose of an EPR valve...
Both technicians are incorrect
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An open internal overload protector
Both technicians are correct

44. 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...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
It is used to control refrigerant pressure in the compressor crankcase
High superheat and low discharge pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

45. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An undercharge and low ambient conditions
An open internal overload protector

46. A hard-start kit for an air conditioning system...
Low superheat
The sensing bulb at a lower temperature than the valve body
Increases starting torque
The internal overload is opened

47. 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
Technician B
Lack of airflow
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Dirty condenser - bent condenser fins - and air recirculating over the condenser

48. A commercial customer calls on a 90
A plugged filter drier
Low discharge pressure - high suction pressure - and low amp draw
The system has been overcharged+The system has air trapped in the condenser
'G' to 'C'

49. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
An overcharged system
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The discharge pressure increases and the amperage increases
Bad compressor valve

50. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
High superheat and low discharge pressure
'G' to 'C'
High suction pressure and low superheat