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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 bad compressor discharge valve...
50-65
Technician B
Technician B
Low discharge pressure - high suction pressure - and low amp draw

2. What is the purpose of a CPR valve...
Broken rings+broken valves+seized bearings
Broken rings+broken valves+seized bearings
It is used to control refrigerant pressure in the compressor crankcase
A restricted metering device

3. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Broken rings+broken valves+seized bearings
The superheat increases and the subcooling decreases
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Bad compressor valve

4. A customer calls with an insufficient cooling complaint on a 90
Technician B
Broken rings+broken valves+seized bearings
The sight glass is full of liquid+the sight glass is full of gas
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

5. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Rise more than normal
An undercharge and low ambient conditions
Lack of airflow
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

6. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Contains a solenoid coil and one or more sets of contacts
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An undercharge and low ambient conditions
Both technicians are correct

7. 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
A low refrigerant charge
Lack of airflow
The superheat will increase and the low-side pressure will decrease
Technician A

8. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A plugged filter drier
110-120
Technician B

9. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Technician B
The oil pump pressure and the crankcase pressure
A defective circuit breaker
A dirty condenser - recirculation of condenser air - and a defective condenser fan

10. A compressor having tight bearings would cause the current value to...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
It is used to control refrigerant pressure in the compressor crankcase
Rise more than normal
Increases starting torque

11. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Technician B
Low discharge pressure - high suction pressure - and low amp draw
Both technicians are correct

12. 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
An uninsulated TXV sensing bulb
An undercharged system+insufficient airflow over the evaporator coil
Technician B
A defective circuit breaker

13. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A low refrigerant charge
The superheat increases and the subcooling decreases
A missing air filter+improper rotation of the indoor blower+blower too small
Low superheat

14. The internal overload of an air conditioning compressor senses winding temperature and...
Technician B
A bad thermostat
Current in the compressor circuit
The discharge pressure increases and the amperage increases

15. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The oil pump pressure and the crankcase pressure
Rise more than normal
An undercharge and low ambient conditions
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

16. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
'G' to 'C'
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician A is correct

17. 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
An overcharged system
It would cause the low-side pressure to decrease
Technician A
Both technicians are correct

18. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A sensing bulb improperly connected to the suction line
An overcharged system
An acid-core suction line drier
It would cause the low-side pressure to decrease

19. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
The superheat will increase and the low-side pressure will decrease
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
('Y' and 'C') and ('G' and 'C')
An open internal overload protector

20. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
Technician B
Technician B
The sight glass is full of liquid+the sight glass is full of gas

21. 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
A plugged filter drier
Both technicians are incorrect
An open internal overload protector
It is used to control refrigerant pressure in the compressor crankcase

22. A system that is operating with a clear sight glass shows...
Whenever necessary
A start capacitor and a solid-state relay
The sight glass is full of liquid+the sight glass is full of gas
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

23. 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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24. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Bad compressor valve
20 to 30

25. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A sensing bulb improperly connected to the suction line
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A missing air filter+improper rotation of the indoor blower+blower too small

26. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
Low discharge pressure - high suction pressure - and low amp draw
An overcharged system
An undercharge and low ambient conditions

27. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
The sight glass is full of liquid+the sight glass is full of gas
Clean the condenser coil
Contains a solenoid coil and one or more sets of contacts

28. 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
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

29. 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
It would cause the low-side pressure to decrease
Technician A is correct
A start capacitor and a solid-state relay
Technician B

30. What causes the automatic expansion valve to close...
A defective circuit breaker
Rise more than normal
An increase in low-side pressure
Bad compressor valve

31. The internal overload of an air conditioning compressor senses winding temperature and...
A blown fuse
Current in the compressor circuit
An increase in low-side pressure
It is used to control refrigerant pressure in the compressor crankcase

32. What component is most often the cause of a start capacitor failure...
A start relay
It keeps a constant superheat in the evaporator
An overcharged system
A blown fuse

33. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The oil pump pressure and the crankcase pressure
Technician B
An open internal overload protector
The superheat will increase and the low-side pressure will decrease

34. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
An overcharged system
Technician A is correct
An undercharged system+insufficient airflow over the evaporator coil
20 to 30

35. 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
Technician B
Technician A is correct
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

36. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The oil pump pressure and the crankcase pressure
An increase in suction pressure and an increase in discharge pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

37. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Technician B
Rise more than normal
A missing air filter+improper rotation of the indoor blower+blower too small
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

38. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

39. 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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40. What causes the automatic expansion valve to close...
50-65
An increase in low-side pressure
Both technicians are correct
A start capacitor and a solid-state relay

41. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
Technician A is correct
The internal overload is opened
The sight glass is full of liquid+the sight glass is full of gas

42. 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...
The superheat increases and the subcooling decreases
A start capacitor and a solid-state relay
High superheat and low discharge pressure
Lack of airflow

43. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
3 psig
A start capacitor and a solid-state relay

44. 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
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It keeps a constant superheat in the evaporator
A missing air filter+improper rotation of the indoor blower+blower too small

45. What is the common cause of a compressor burnout...
A missing air filter+improper rotation of the indoor blower+blower too small
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

46. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Run with high head and high suction pressure
Increases starting torque
Lack of airflow

47. 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...
Both technicians are correct
Low voltage and a faulty start relay
An open internal overload protector
A missing air filter+improper rotation of the indoor blower+blower too small

48. 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
The discharge pressure increases and the amperage increases
50-65
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

49. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
The sensing bulb at a lower temperature than the valve body
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A bad thermostat
A start relay

50. 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
Run with high head and high suction pressure
The superheat will increase and the low-side pressure will decrease
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Both technicians are incorrect