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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...
Low discharge pressure - high suction pressure - and low amp draw
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The superheat increases and the subcooling decreases

2. A system that uses a thermal electric expansion valve...
High suction pressure and low superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The internal overload is opened
Both technicians are incorrect

3. A customer calls with an insufficient cooling complaint on a 90
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
It is used to control refrigerant pressure in the compressor crankcase
110-120

4. Superheat is found in an air conditioning system in the...
A missing air filter+improper rotation of the indoor blower+blower too small
Technician A
The low-side pressure will decrease and the evaporator coil will be partially frosted
Evaporator and compressor

5. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Low discharge pressure - high suction pressure - and low amp draw
Bad compressor valve

6. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Broken rings+broken valves+seized bearings
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

7. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The superheat will increase and the low-side pressure will decrease
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An undercharge and low ambient conditions

8. The internal overload of an air conditioning compressor senses winding temperature and...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Current in the compressor circuit
Short cycling and insufficient dehumidification
The internal overload is opened

9. 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...
Rise more than normal
A start relay
A bad thermostat
The internal overload is opened

10. What are the operating pressures of an oil pressure safety switch...
Lack of airflow
Technician A
The oil pump pressure and the crankcase pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

11. A party-store owner tried to adjust the water valve on his water-cooled condensing unit - then he called for assistance from an HVAC/are service technician. It was found that when servicing the unit - the outlet water temperature was too low. Technic
Flooding the condenser - cycling condenser fans - and dampering condenser air
A missing air filter+improper rotation of the indoor blower+blower too small
The sensing bulb at a lower temperature than the valve body
Technician B

12. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Contains a solenoid coil and one or more sets of contacts
The external equalizer could be plugged
Both technicians are incorrect

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
High superheat and low discharge pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Always have some liquid present in the bulb and diaphragm
The superheat increases and the subcooling decreases

14. The best description of a relay would be...
Technician B
Contains a solenoid coil and one or more sets of contacts
High superheat and low discharge pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

15. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Broken rings+broken valves+seized bearings
110-120
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Increases starting torque

16. Air filters should be replaced...
Whenever necessary
Low discharge pressure - high suction pressure - and low amp draw
High suction pressure and low superheat
The internal overload is opened

17. What component is most often the cause of a start capacitor failure...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A start relay
Lack of airflow
High superheat and low discharge pressure

18. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The superheat will increase and the low-side pressure will decrease
It keeps a constant superheat in the evaporator
An increase in suction pressure and an increase in discharge pressure
3 psig

19. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Clean the condenser coil
An acid-core suction line drier
Technician B
Bad compressor valve

20. 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
Rise more than normal
Bad compressor valve
A bad thermostat

21. 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
An overcharged system
A defective circuit breaker
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

22. What are two common symptoms of refrigerant leaks in an air conditioning system...
Lack of airflow
It is used to control refrigerant pressure in the compressor crankcase
3 psig
Partially frosted evaporator and high superheat

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. 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
The discharge pressure increases and the amperage increases
A sensing bulb improperly connected to the suction line
Technician B

25. A system that is operating with a clear sight glass shows...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The sight glass is full of liquid+the sight glass is full of gas
An increase in suction pressure and an increase in discharge pressure

26. 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...
Technician B
Both technicians are incorrect
Low voltage and a faulty start relay
Short cycling and insufficient dehumidification

27. 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 increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B
High superheat and low discharge pressure
3 psig

28. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
A blown fuse
A start capacitor and a solid-state relay
An uninsulated suction line and a restricted metering device
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

29. What causes the automatic expansion valve to close...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An increase in low-side pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The sensing bulb at a lower temperature than the valve body

30. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A missing air filter+improper rotation of the indoor blower+blower too small
Bad compressor valve
Increases starting torque

31. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
An uninsulated TXV sensing bulb
The oil pump pressure and the crankcase pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
20 to 30

32. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
Both technicians are incorrect
An overcharged system
Dirty condenser - bent condenser fins - and air recirculating over the condenser

33. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
The sight glass is full of liquid+the sight glass is full of gas
A blown fuse
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Contains a solenoid coil and one or more sets of contacts

34. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
An overcharged system
An undercharge and low ambient conditions
Always have some liquid present in the bulb and diaphragm

35. What problem or problems can cause low discharge and suction pressure...
Contains a solenoid coil and one or more sets of contacts
The discharge pressure increases and the amperage increases
Rise more than normal
An undercharged system+insufficient airflow over the evaporator coil

36. 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 vacuum test+oil traces around fittings+soap bubble solution
A low refrigerant charge
A bad thermostat
Low discharge pressure - high suction pressure - and low amp draw

37. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
The superheat increases and the subcooling decreases
'G' to 'C'
A restricted metering device
Lack of airflow

38. 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
Both technicians are correct
The internal overload is opened
Technician B
A plugged filter drier

39. The temperature range of the suction line from an air conditioning system should be...
50-65
Short cycling and insufficient dehumidification
An undercharged system+insufficient airflow over the evaporator coil
An overcharged system

40. What is the common cause of a compressor burnout...
Clean the condenser coil
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An increase in low-side pressure

41. Insufficient airflow can be caused by...
Current in the compressor circuit
An increase in suction pressure and an increase in discharge pressure
An open internal overload protector
An increase of air leakage from ductwork

42. 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 vacuum test+oil traces around fittings+soap bubble solution
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A defective circuit breaker
Technician B

43. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Technician B
Technician A
Lack of airflow
The superheat will increase and the low-side pressure will decrease

44. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
A blown fuse
Technician A is correct
Low discharge pressure - high suction pressure - and low amp draw
Flooding the condenser - cycling condenser fans - and dampering condenser air

45. A hard-start kit for an air conditioning system...
'G' to 'C'
Increases starting torque
An acid-core suction line drier
Short cycling and insufficient dehumidification

46. A liquid-charged TXV bulb will...
It is used to control refrigerant pressure in the compressor crankcase
Always have some liquid present in the bulb and diaphragm
An undercharge and low ambient conditions
A defective circuit breaker

47. When using a vapor-charged TXV bulb - it is necessary to have...
An increase in suction pressure and an increase in discharge pressure
Technician B
Contains a solenoid coil and one or more sets of contacts
The sensing bulb at a lower temperature than the valve body

48. 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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49. 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...
Clean the condenser coil
Low voltage and a faulty start relay
('Y' and 'C') and ('G' and 'C')
An uninsulated TXV sensing bulb

50. A party-store owner tried to adjust the water valve on his water-cooled condensing unit - then he called for assistance from an HVAC/are service technician. It was found that when servicing the unit - the outlet water temperature was too low. Technic
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B
Short cycling and insufficient dehumidification
Increases starting torque