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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 are the symptoms of an air conditioning system that has a low charge...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
An increase in low-side pressure

2. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician B
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
Both technicians are incorrect

3. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The internal overload is opened
An increase of air leakage from ductwork

4. A hard-start kit consists of...
An overcharged system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician A
A start capacitor and a solid-state relay

5. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Bad compressor valve
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
50-65

6. What are the operating pressures of an oil pressure safety switch...
The sight glass is full of liquid+the sight glass is full of gas
The superheat increases and the subcooling decreases
The oil pump pressure and the crankcase pressure
Low discharge pressure - high suction pressure - and low amp draw

7. Which of the following can cause low superheat in a TXV system...
Clean the condenser coil
Condenser fans operating during a low ambient condition and a low suction pressure
An uninsulated TXV sensing bulb
Bad compressor valve

8. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Technician A is correct
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A restricted metering device
Technician B

9. 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
A vacuum test+oil traces around fittings+soap bubble solution
Both technicians are incorrect
Technician B
3 psig

10. When using a vapor-charged TXV bulb - it is necessary to have...
Both technicians are correct
The sensing bulb at a lower temperature than the valve body
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in suction pressure and an increase in discharge pressure

11. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Bad compressor valve
An increase in suction pressure and an increase in discharge pressure
Current in the compressor circuit
An overcharged system

12. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Run with high head and high suction pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
'G' to 'C'
A missing air filter+improper rotation of the indoor blower+blower too small

13. 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 was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician A
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A plugged filter drier

14. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The superheat increases and the subcooling decreases
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A start relay
A low refrigerant charge

15. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Increases starting torque
Technician B
Both technicians are incorrect

16. What is the common cause of a compressor burnout...
Run with high head and high suction pressure
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B

17. 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
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 blown fuse
Bad compressor valve

18. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
A sensing bulb improperly connected to the suction line
Lack of airflow
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An acid-core suction line drier

19. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A defective circuit breaker
An increase in low-side pressure
20 to 30
The superheat increases and the subcooling decreases

20. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A defective circuit breaker
A dirty condenser - recirculation of condenser air - and a defective condenser fan
20 to 30

21. 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
The sensing bulb at a lower temperature than the valve body
An undercharged system+insufficient airflow over the evaporator coil
A blown fuse

22. A hard-start kit for an air conditioning system...
Both technicians are incorrect
20 to 30
Increases starting torque
Condenser fans operating during a low ambient condition and a low suction pressure

23. What are the operating pressures of an oil pressure safety switch...
The superheat will increase and the low-side pressure will decrease
Technician B
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

24. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
An increase in suction pressure and an increase in discharge pressure
High suction pressure and low superheat
110-120
An overcharged system

25. 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...
Both technicians are incorrect
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
High superheat and low discharge pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

26. 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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The internal overload is opened
An increase in suction pressure and an increase in discharge pressure
Technician B

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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A blown fuse
A bad thermostat
An overcharged system

28. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
('Y' and 'C') and ('G' and 'C')
20 to 30

29. What problem or problems can cause low discharge and suction pressure...
Broken rings+broken valves+seized bearings
An increase of air leakage from ductwork
A defective circuit breaker
An undercharged system+insufficient airflow over the evaporator coil

30. The internal overload of an air conditioning compressor senses winding temperature and...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Current in the compressor circuit
A defective circuit breaker
Low discharge pressure - high suction pressure - and low amp draw

31. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

32. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Both technicians are incorrect
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Low voltage and a faulty start relay

33. 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...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Clean the condenser coil
The internal overload is opened

34. Which of the following will cause excessive discharge pressures on an air conditioning system...
An open internal overload protector
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
3 psig
An overcharged system

35. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
An increase in low-side pressure
Rise more than normal
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

36. 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
Both technicians are incorrect
A start relay
Technician B
An acid-core suction line drier

37. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
('Y' and 'C') and ('G' and 'C')
Flooding the condenser - cycling condenser fans - and dampering condenser air
The low-side pressure will decrease and the evaporator coil will be partially frosted

38. A restricted air filter in an air conditioning system can be identified by...
An undercharge and low ambient conditions
50-65
Low superheat
A sensing bulb improperly connected to the suction line

39. 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...
Short cycling and insufficient dehumidification
Condenser fans operating during a low ambient condition and a low suction pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Current in the compressor circuit

40. 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
It keeps a constant superheat in the evaporator
Technician B
An increase of air leakage from ductwork
Partially frosted evaporator and high superheat

41. A system that is operating with a clear sight glass shows...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician A
Low superheat
The sight glass is full of liquid+the sight glass is full of gas

42. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Low discharge pressure - high suction pressure - and low amp draw
A blown fuse
An overcharged system
Lack of airflow

43. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated suction line and a restricted metering device
('Y' and 'C') and ('G' and 'C')
High superheat and low discharge pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

44. What are two common symptoms of refrigerant leaks in an air conditioning system...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Rise more than normal
Partially frosted evaporator and high superheat
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
An open internal overload protector
An increase in suction pressure and an increase in discharge pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
Dirty condenser - bent condenser fins - and air recirculating over the condenser

46. 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 dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

47. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
'G' to 'C'
'G' to 'C'
Both technicians are correct

48. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
The internal overload is opened
A vacuum test+oil traces around fittings+soap bubble solution
The system has been overcharged+The system has air trapped in the condenser

49. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Current in the compressor circuit
An overcharged system
The sight glass is full of liquid+the sight glass is full of gas
High suction pressure and low superheat

50. A restricted air filter in an air conditioning system can be identified by...
Technician B
Short cycling and insufficient dehumidification
Low superheat
An acid-core suction line drier