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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. 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...
It would cause the low-side pressure to decrease
High superheat and low discharge pressure
An increase in suction pressure and an increase in discharge pressure
Technician B

2. A hard-start kit for an air conditioning system...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Evaporator and compressor
Increases starting torque
20 to 30

3. A compressor having tight bearings would cause the current value to...
Partially frosted evaporator and high superheat
Rise more than normal
Current in the compressor circuit
Technician B

4. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Both technicians are incorrect
An overcharged system
An undercharge and low ambient conditions
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

5. What problem or problems can cause low discharge and suction pressure...
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
An undercharged system+insufficient airflow over the evaporator coil
An acid-core suction line drier

6. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
An open internal overload protector
Short cycling and insufficient dehumidification
A blown fuse
Lack of airflow

7. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Low superheat
A plugged filter drier
Current in the compressor circuit
An uninsulated suction line and a restricted metering device

8. A hard-start kit consists of...
110-120
A start capacitor and a solid-state relay
Clean the condenser coil
Both technicians are incorrect

9. 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 restricted metering device
Broken rings+broken valves+seized bearings
A defective circuit breaker
3 psig

10. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Partially frosted evaporator and high superheat
Short cycling and insufficient dehumidification
Clean the condenser coil
A missing air filter+improper rotation of the indoor blower+blower too small

11. Which of the following can cause low superheat in a TXV system...
An increase in suction pressure and an increase in discharge pressure
It is used to control refrigerant pressure in the compressor crankcase
Clean the condenser coil
An uninsulated TXV sensing bulb

12. 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...
Contains a solenoid coil and one or more sets of contacts
The internal overload is opened
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are incorrect

13. Which of the following is a common cause of an excessively low superheat on a TXV system...
The oil pump pressure and the crankcase pressure
An uninsulated suction line and a restricted metering device
It keeps a constant superheat in the evaporator
A sensing bulb improperly connected to the suction line

14. What causes the automatic expansion valve to close...
An increase in low-side pressure
Both technicians are correct
An undercharged system+insufficient airflow over the evaporator coil
High superheat and low discharge pressure

15. What is the purpose of a CPR valve...
Whenever necessary
Both technicians are incorrect
Technician A is correct
It is used to control refrigerant pressure in the compressor crankcase

16. Which of the following will cause excessive discharge pressures on an air conditioning system...
The internal overload is opened
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The external equalizer could be plugged
An increase in suction pressure and an increase in discharge pressure

17. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An open internal overload protector
Technician B
Rise more than normal
An uninsulated suction line and a restricted metering device

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
A start relay
Bad compressor valve
Technician A is correct
An increase of air leakage from ductwork

19. 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 dirty condenser - recirculation of condenser air - and a defective condenser fan
A blown fuse
An undercharged system+insufficient airflow over the evaporator coil
Technician A

20. Which of the following will cause excessive discharge pressures on an air conditioning system...
A blown fuse
The low-side pressure will decrease and the evaporator coil will be partially frosted
A plugged filter drier
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

21. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
110-120
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A blown fuse

22. A restricted air filter in an air conditioning system can be identified by...
('Y' and 'C') and ('G' and 'C')
Partially frosted evaporator and high superheat
Low superheat
Increases starting torque

23. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase in suction pressure and an increase in discharge pressure

24. Superheat is found in an air conditioning system in the...
Evaporator and compressor
Low discharge pressure - high suction pressure - and low amp draw
A bad thermostat
Whenever necessary

25. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Low superheat
Partially frosted evaporator and high superheat
Rise more than normal
A missing air filter+improper rotation of the indoor blower+blower too small

26. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Condenser fans operating during a low ambient condition and a low suction pressure
The superheat increases and the subcooling decreases
An acid-core suction line drier
An undercharge and low ambient conditions

27. 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 undercharged system+insufficient airflow over the evaporator coil
Technician B
Contains a solenoid coil and one or more sets of contacts
Both technicians are incorrect

28. 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 system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A sensing bulb improperly connected to the suction line
Both technicians are correct
Evaporator and compressor

29. Insufficient airflow can be caused by...
Technician B
An increase of air leakage from ductwork
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

30. What are the operating pressures of an oil pressure safety switch...
Both technicians are correct
The oil pump pressure and the crankcase pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A missing air filter+improper rotation of the indoor blower+blower too small

31. 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...
An overcharged system
The superheat increases and the subcooling decreases
A start capacitor and a solid-state relay
Condenser fans operating during a low ambient condition and a low suction pressure

32. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...

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33. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A start capacitor and a solid-state relay
A bad thermostat

34. What is the purpose of a CPR valve...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It is used to control refrigerant pressure in the compressor crankcase
Dirty condenser - bent condenser fins - and air recirculating over the condenser
3 psig

35. 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 plugged air filter+a bad indoor blower relay
A plugged filter drier
A bad thermostat

36. The internal overload of an air conditioning compressor senses winding temperature and...
An undercharge and low ambient conditions
A restricted metering device
Current in the compressor circuit
The discharge pressure increases and the amperage increases

37. 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 missing air filter+improper rotation of the indoor blower+blower too small
Technician B
50-65
Low voltage and a faulty start relay

38. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
Low superheat
A start relay
Whenever necessary

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...
Condenser fans operating during a low ambient condition and a low suction pressure
An undercharged system+insufficient airflow over the evaporator coil
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A low refrigerant charge

40. Why is it unsafe to operate an air conditioning system with a low charge...
The sensing bulb at a lower temperature than the valve body
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Whenever necessary
Technician A is correct

41. Which of the following could be the cause for a system's discharge and suction pressure being low...
The discharge pressure increases and the amperage increases
A restricted metering device
An increase in low-side pressure
Rise more than normal

42. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Clean the condenser coil
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

43. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An increase in suction pressure and an increase in discharge pressure
Both technicians are incorrect
The superheat increases and the subcooling decreases
Always have some liquid present in the bulb and diaphragm

44. A compressor having tight bearings would cause the current value to...
A defective circuit breaker
Rise more than normal
Technician B
Whenever necessary

45. What is the purpose of the TXV...
The low-side pressure will decrease and the evaporator coil will be partially frosted
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It keeps a constant superheat in the evaporator
The oil pump pressure and the crankcase 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
A plugged filter drier
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
A low refrigerant charge

47. What problem can cause an increase of discharge pressure and an increase of suction pressure...
20 to 30
A bad thermostat
The superheat increases and the subcooling decreases
An overcharged system

48. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The superheat will increase and the low-side pressure will decrease
The external equalizer could be plugged
110-120

49. What is the purpose of an EPR valve...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A bad thermostat
Condenser fans operating during a low ambient condition and a low suction pressure

50. 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 blown fuse
Technician B
Rise more than normal
A bad thermostat