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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. A restricted air filter in an air conditioning system can be identified by...
Low voltage and a faulty start relay
High suction pressure and low superheat
Low superheat
An uninsulated suction line and a restricted metering device

2. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
An uninsulated suction line and a restricted metering device
A sensing bulb improperly connected to the suction line
High suction pressure and low superheat
Technician B

3. 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...
Low voltage and a faulty start relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Clean the condenser coil
Dirty condenser - bent condenser fins - and air recirculating over the condenser

4. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An undercharged system+insufficient airflow over the evaporator coil
A missing air filter+improper rotation of the indoor blower+blower too small
It would cause the low-side pressure to decrease
The internal overload is opened

5. What are the symptoms of an air conditioning system that has a low charge...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician A is correct
The low-side pressure will decrease and the evaporator coil will be partially frosted
20 to 30

6. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The discharge pressure increases and the amperage increases
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The superheat will increase and the low-side pressure will decrease
An overcharged system

7. 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
A sensing bulb improperly connected to the suction line
Whenever necessary
Technician B

8. 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
Broken rings+broken valves+seized bearings
Technician B
('Y' and 'C') and ('G' and 'C')
Low superheat

9. What is the purpose of an EPR valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A bad thermostat
('Y' and 'C') and ('G' and 'C')
Increases starting torque

10. 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
A sensing bulb improperly connected to the suction line
An open internal overload protector
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Both technicians are incorrect

11. 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
Technician B
A defective circuit breaker
A start relay
Technician A

12. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A restricted metering device
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The system has been overcharged+The system has air trapped in the condenser

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
The oil pump pressure and the crankcase pressure
It would cause the low-side pressure to decrease
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Bad compressor valve

14. 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
The superheat will increase and the low-side pressure will decrease
A plugged filter drier
Low voltage and a faulty start relay
Both technicians are incorrect

15. What are the operating pressures of an oil pressure safety switch...
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
Contains a solenoid coil and one or more sets of contacts
Always have some liquid present in the bulb and diaphragm

16. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A plugged filter drier
('Y' and 'C') and ('G' and 'C')
An overcharged system

17. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The discharge pressure increases and the amperage increases
An increase in suction pressure and an increase in discharge pressure
Both technicians are incorrect
Low superheat

18. 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...
Clean the condenser coil
Technician A
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
High superheat and low discharge pressure

19. 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 start capacitor and a solid-state relay
Technician B
Low voltage and a faulty start relay
A missing air filter+improper rotation of the indoor blower+blower too small

20. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
3 psig

21. 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
Clean the condenser coil
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
Technician B

22. 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 bad thermostat
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The internal overload is opened
Low superheat

23. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
An undercharged system+insufficient airflow over the evaporator coil
An increase in low-side pressure
Rise more than normal

24. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Both technicians are incorrect
A bad thermostat
An undercharge and low ambient conditions
The sensing bulb at a lower temperature than the valve body

25. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
High suction pressure and low superheat
An undercharge and low ambient conditions

26. The temperature range of the suction line from an air conditioning system should be...
50-65
An overcharged system
Run with high head and high suction pressure
The oil pump pressure and the crankcase pressure

27. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Broken rings+broken valves+seized bearings
'G' to 'C'
A blown fuse

28. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
Low superheat
Both technicians are correct
A low refrigerant charge

29. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Evaporator and compressor
An open internal overload protector

30. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Run with high head and high suction pressure
An increase in low-side pressure
Increases starting torque

31. 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
High suction pressure and low superheat
An undercharged system+insufficient airflow over the evaporator coil
It would cause the low-side pressure to decrease

32. The internal overload of an air conditioning compressor senses winding temperature and...
It is used to control refrigerant pressure in the compressor crankcase
Partially frosted evaporator and high superheat
The sensing bulb at a lower temperature than the valve body
Current in the compressor circuit

33. 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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34. 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
An undercharge and low ambient conditions
Technician B
Increases starting torque
Always have some liquid present in the bulb and diaphragm

35. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
A plugged filter drier
The sensing bulb at a lower temperature than the valve body
Whenever necessary
The discharge pressure increases and the amperage increases

36. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
The oil pump pressure and the crankcase pressure
The superheat increases and the subcooling decreases
Bad compressor valve

37. A hard-start kit for an air conditioning system...
The oil pump pressure and the crankcase pressure
'G' to 'C'
20 to 30
Increases starting torque

38. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
50-65
20 to 30

39. What are the operating pressures of an oil pressure safety switch...
The external equalizer could be plugged
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The oil pump pressure and the crankcase pressure
The discharge pressure increases and the amperage increases

40. 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
3 psig
A start capacitor and a solid-state relay
A bad thermostat
Both technicians are incorrect

41. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
50-65
A start capacitor and a solid-state relay
An undercharge and low ambient conditions
Low discharge pressure - high suction pressure - and low amp draw

42. A commercial customer calls on a 90
It keeps a constant superheat in the evaporator
An open internal overload protector
The system has been overcharged+The system has air trapped in the condenser
An uninsulated suction line and a restricted metering device

43. Which of the following can cause low superheat in a TXV system...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An uninsulated TXV sensing bulb
An overcharged system
A restricted metering device

44. What is the purpose of the TXV...
Evaporator and compressor
Both technicians are correct
It keeps a constant superheat in the evaporator
The internal overload is opened

45. 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 uninsulated suction line and a restricted metering device
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are correct

46. A 220-volt 30-amp motor circuit keeps tripping the breaker after the motor is started. The starting amperage is 60 amps. When measuring the amperage of the circuit - This is drawn for a brief moment. After startup - the amperage drops to 22 amps and
A restricted metering device
Technician A is correct
A defective circuit breaker
It would cause the low-side pressure to decrease

47. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
Low discharge pressure - high suction pressure - and low amp draw
Technician A
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

48. 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 external equalizer could be plugged
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A restricted metering device

49. Which of the following is a possible cause for a compressor to overheat...
Increases starting torque
Clean the condenser coil
An open internal overload protector
A low refrigerant charge

50. 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
An increase of air leakage from ductwork
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Contains a solenoid coil and one or more sets of contacts