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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 is the common cause of a compressor burnout...
An increase of air leakage from ductwork
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Both technicians are incorrect
High suction pressure and low superheat

2. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The superheat will increase and the low-side pressure will decrease
Flooding the condenser - cycling condenser fans - and dampering condenser air

3. What causes the automatic expansion valve to close...
An increase in low-side pressure
It would cause the low-side pressure to decrease
Low discharge pressure - high suction pressure - and low amp draw
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

4. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
An overcharged system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
3 psig
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

5. 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
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A blown fuse
A bad thermostat

6. 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 vacuum test+oil traces around fittings+soap bubble solution
Technician A is correct
Lack of airflow
Technician B

7. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Low voltage and a faulty start relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
The discharge pressure increases and the amperage increases

8. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
The sensing bulb at a lower temperature than the valve body
An acid-core suction line drier
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are correct

9. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
A vacuum test+oil traces around fittings+soap bubble solution
Contains a solenoid coil and one or more sets of contacts
An undercharged system+insufficient airflow over the evaporator coil

10. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Rise more than normal
Contains a solenoid coil and one or more sets of contacts
Bad compressor valve
Condenser fans operating during a low ambient condition and a low suction pressure

11. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An uninsulated TXV sensing bulb
Clean the condenser coil

12. What are the operating pressures of an oil pressure safety switch...
The superheat increases and the subcooling decreases
The low-side pressure will decrease and the evaporator coil will be partially frosted
The oil pump pressure and the crankcase pressure
A plugged filter drier

13. What are the symptoms of a TXV air conditioning system if it has lost its charge...
An undercharge and low ambient conditions
An uninsulated TXV sensing bulb
Short cycling and insufficient dehumidification
The superheat will increase and the low-side pressure will decrease

14. 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
Technician B
Both technicians are incorrect
Low discharge pressure - high suction pressure - and low amp draw
A low refrigerant charge

15. A system that is operating with a clear sight glass shows...
The oil pump pressure and the crankcase pressure
Contains a solenoid coil and one or more sets of contacts
The sight glass is full of liquid+the sight glass is full of gas
A dirty condenser - recirculation of condenser air - and a defective condenser fan

16. What is the purpose of a CPR valve...
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
It is used to control refrigerant pressure in the compressor crankcase
An increase of air leakage from ductwork

17. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A defective circuit breaker
Always have some liquid present in the bulb and diaphragm
Low discharge pressure - high suction pressure - and low amp draw
An increase in suction pressure and an increase in discharge pressure

18. 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
Low superheat
An undercharged system+insufficient airflow over the evaporator coil
Technician B
Both technicians are correct

19. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Bad compressor valve
Low superheat
110-120
A dirty condenser - recirculation of condenser air - and a defective condenser fan

20. What component is most often the cause of a start capacitor failure...
Technician B
A start relay
'G' to 'C'
Run with high head and high suction pressure

21. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The sensing bulb at a lower temperature than the valve body
Broken rings+broken valves+seized bearings

22. What problem or problems can cause low discharge and suction pressure...
Technician B
A start relay
The external equalizer could be plugged
An undercharged system+insufficient airflow over the evaporator coil

23. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A missing air filter+improper rotation of the indoor blower+blower too small
Low voltage and a faulty start relay
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
50-65

24. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A restricted metering device
The internal overload is opened
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B

25. Which of the following is a possible cause for a compressor to overheat...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An uninsulated TXV sensing bulb
Low voltage and a faulty start relay
A low refrigerant charge

26. 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 defective circuit breaker
The superheat will increase and the low-side pressure will decrease
20 to 30
Technician B

27. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Flooding the condenser - cycling condenser fans - and dampering condenser air
The system has been overcharged+The system has air trapped in the condenser
An uninsulated suction line and a restricted metering device
Technician A is correct

28. 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
Both technicians are correct
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
Current in the compressor circuit

29. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
Technician B
Always have some liquid present in the bulb and diaphragm
The external equalizer could be plugged

30. A hard-start kit consists of...
A start capacitor and a solid-state relay
Whenever necessary
20 to 30
An increase in suction pressure and an increase in discharge pressure

31. Air filters should be replaced...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An overcharged system
Whenever necessary
Condenser fans operating during a low ambient condition and a low suction pressure

32. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A plugged filter drier
'G' to 'C'
It keeps a constant superheat in the evaporator
The superheat increases and the subcooling decreases

33. What problem or problems can cause low discharge and suction pressure...
The oil pump pressure and the crankcase pressure
3 psig
An undercharged system+insufficient airflow over the evaporator coil
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

34. What are the operating pressures of an oil pressure safety switch...
Low discharge pressure - high suction pressure - and low amp draw
The oil pump pressure and the crankcase pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A missing air filter+improper rotation of the indoor blower+blower too small

35. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
Always have some liquid present in the bulb and diaphragm
An increase in suction pressure and an increase in discharge pressure
Technician B

36. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Technician B
Lack of airflow
Current in the compressor circuit
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

37. What is the purpose of the TXV...
Technician A
Low discharge pressure - high suction pressure - and low amp draw
Clean the condenser coil
It keeps a constant superheat in the evaporator

38. 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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39. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
A low refrigerant charge
An undercharge and low ambient conditions
20 to 30
Broken rings+broken valves+seized bearings

40. A compressor having tight bearings would cause the current value to...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An undercharged system+insufficient airflow over the evaporator coil
Rise more than normal
Technician B

41. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
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
Technician B

42. When using a vapor-charged TXV bulb - it is necessary to have...
The system has been overcharged+The system has air trapped in the condenser
110-120
The sensing bulb at a lower temperature than the valve body
Whenever necessary

43. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
The sensing bulb at a lower temperature than the valve body
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

44. Superheat is found in an air conditioning system in the...
Technician B
Lack of airflow
Evaporator and compressor
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

45. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Evaporator and compressor
20 to 30
The low-side pressure will decrease and the evaporator coil will be partially frosted
The low-side pressure will decrease and the evaporator coil will be partially frosted

46. 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
Condenser fans operating during a low ambient condition and a low suction pressure
Partially frosted evaporator and high superheat
Low superheat
Technician A is correct

47. 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
It keeps a constant superheat in the evaporator
Both technicians are incorrect
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

48. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Increases starting torque
An open internal overload protector
An uninsulated TXV sensing bulb

49. The internal overload of an air conditioning compressor senses winding temperature and...
Both technicians are incorrect
Technician B
Current in the compressor circuit
Low voltage and a faulty start relay

50. 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...
High superheat and low discharge pressure
Whenever necessary
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B