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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 component is most often the cause of a start capacitor failure...
50-65
Whenever necessary
A start relay
An uninsulated suction line and a restricted metering device

2. 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
Broken rings+broken valves+seized bearings
High superheat and low discharge pressure
It is used to control refrigerant pressure in the compressor crankcase
An increase in suction pressure and an increase in discharge pressure

3. What are the operating pressures of an oil pressure safety switch...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The oil pump pressure and the crankcase pressure
Both technicians are incorrect
A blown fuse

4. 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...
3 psig
Lack of airflow
The discharge pressure increases and the amperage increases
A blown fuse

5. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
('Y' and 'C') and ('G' and 'C')

6. 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
Lack of airflow
Both technicians are incorrect
Always have some liquid present in the bulb and diaphragm

7. What are the symptoms of a TXV air conditioning system if it has lost its charge...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Low superheat
The superheat will increase and the low-side pressure will decrease
110-120

8. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Both technicians are incorrect
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

9. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An increase in suction pressure and an increase in discharge pressure
A missing air filter+improper rotation of the indoor blower+blower too small

10. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
An undercharge and low ambient conditions
A blown fuse
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

11. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
Low voltage and a faulty start relay
A start relay
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

12. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are incorrect
'G' to 'C'
3 psig

13. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
A defective circuit breaker
110-120
Technician B

14. When using a vapor-charged TXV bulb - it is necessary to have...
'G' to 'C'
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The sensing bulb at a lower temperature than the valve body
A start relay

15. A hard-start kit for an air conditioning system...
Increases starting torque
An open internal overload protector
A sensing bulb improperly connected to the suction line
An overcharged system

16. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Condenser fans operating during a low ambient condition and a low suction pressure
The discharge pressure increases and the amperage increases
A start relay
Short cycling and insufficient dehumidification

17. 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
Both technicians are incorrect
High superheat and low discharge pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
An open internal overload protector

18. 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
An overcharged system
Broken rings+broken valves+seized bearings
An overcharged system

19. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An increase in suction pressure and an increase in discharge pressure
('Y' and 'C') and ('G' and 'C')

20. 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
The oil pump pressure and the crankcase pressure
A defective circuit breaker
Both technicians are incorrect
It keeps a constant superheat in the evaporator

21. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated TXV sensing bulb
An uninsulated suction line and a restricted metering device
A low refrigerant charge
A sensing bulb improperly connected to the suction line

22. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Low voltage and a faulty start relay
Technician A is correct

23. 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...
Low superheat
The internal overload is opened
An increase of air leakage from ductwork
110-120

24. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The internal overload is opened
The system has been overcharged+The system has air trapped in the condenser

25. A restricted air filter in an air conditioning system can be identified by...
Partially frosted evaporator and high superheat
It is used to control refrigerant pressure in the compressor crankcase
Low superheat
20 to 30

26. 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
Both technicians are correct
A bad thermostat
Broken rings+broken valves+seized bearings
Technician A

27. 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...
Rise more than normal
The sensing bulb at a lower temperature than the valve body
Technician A is correct
A blown fuse

28. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
It would cause the low-side pressure to decrease
Broken rings+broken valves+seized bearings
Technician A

29. A hard-start kit for an air conditioning system...
Increases starting torque
An increase of air leakage from ductwork
It would cause the low-side pressure to decrease
Technician A is correct

30. 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
Low voltage and a faulty start relay
Both technicians are correct
Low superheat

31. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
110-120
High suction pressure and low superheat
Technician B

32. What is the purpose of an EPR valve...
Evaporator and compressor
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B
Technician B

33. The internal overload of an air conditioning compressor senses winding temperature and...
It keeps a constant superheat in the evaporator
An overcharged system
The external equalizer could be plugged
Current in the compressor circuit

34. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
An increase of air leakage from ductwork
The external equalizer could be plugged
Bad compressor valve
A defective circuit breaker

35. What causes the automatic expansion valve to close...
The internal overload is opened
An increase in low-side pressure
High suction pressure and low superheat
Technician B

36. A system that is operating with a clear sight glass shows...
The system has been overcharged+The system has air trapped in the condenser
A vacuum test+oil traces around fittings+soap bubble solution
Technician B
The sight glass is full of liquid+the sight glass is full of gas

37. 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
Always have some liquid present in the bulb and diaphragm
A defective circuit breaker
Current in the compressor circuit
A dirty condenser - recirculation of condenser air - and a defective condenser fan

38. What problem or problems can cause low discharge and suction pressure...
50-65
An undercharged system+insufficient airflow over the evaporator coil
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Always have some liquid present in the bulb and diaphragm

39. Air filters should be replaced...
Technician B
Whenever necessary
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
It keeps a constant superheat in the evaporator

40. The best description of a relay would be...
Partially frosted evaporator and high superheat
Flooding the condenser - cycling condenser fans - and dampering condenser air
Contains a solenoid coil and one or more sets of contacts
Technician A

41. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
It would cause the low-side pressure to decrease
('Y' and 'C') and ('G' and 'C')
The sight glass is full of liquid+the sight glass is full of gas

42. 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
Both technicians are correct
Bad compressor valve
Low superheat

43. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
Increases starting torque
An undercharge and low ambient conditions
Technician A is correct

44. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
A restricted metering device
('Y' and 'C') and ('G' and 'C')
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

45. A hard-start kit consists of...
The external equalizer could be plugged
A start capacitor and a solid-state relay
The oil pump pressure and the crankcase pressure
The sensing bulb at a lower temperature than the valve body

46. 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 increase of air leakage from ductwork
The superheat increases and the subcooling decreases
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Both technicians are incorrect

47. 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 restricted metering device
It is used to control refrigerant pressure in the compressor crankcase
Technician B
Both technicians are correct

48. Air filters should be replaced...
Partially frosted evaporator and high superheat
It keeps a constant superheat in the evaporator
Whenever necessary
The internal overload is opened

49. The temperature range of the suction line from an air conditioning system should be...
An undercharged system+insufficient airflow over the evaporator coil
50-65
An overcharged system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

50. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
It would cause the low-side pressure to decrease
Low discharge pressure - high suction pressure - and low amp draw
An acid-core suction line drier
Both technicians are correct