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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 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
Technician B
It keeps a constant superheat in the evaporator

2. 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
The superheat will increase and the low-side pressure will decrease
Condenser fans operating during a low ambient condition and a low suction pressure
An open internal overload protector
The superheat increases and the subcooling decreases

3. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An increase of air leakage from ductwork
Technician A
An open internal overload protector

4. The internal overload of an air conditioning compressor senses winding temperature and...
The external equalizer could be plugged
Current in the compressor circuit
It would cause the low-side pressure to decrease
An undercharge and low ambient conditions

5. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
Technician A is correct
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An increase in low-side pressure

6. 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
Both technicians are incorrect
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
High suction pressure and low superheat
It keeps a constant superheat in the evaporator

7. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Both technicians are incorrect
Both technicians are correct
Bad compressor valve
Lack of airflow

8. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
'G' to 'C'
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician A is correct
Lack of airflow

9. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Run with high head and high suction pressure
Technician B
Both technicians are correct

10. 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...
A blown fuse
A start capacitor and a solid-state relay
The system has been overcharged+The system has air trapped in the condenser
Current in the compressor circuit

11. 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 increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An increase of air leakage from ductwork
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Whenever necessary

12. 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
Current in the compressor circuit
The sight glass is full of liquid+the sight glass is full of gas
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

13. What are three methods for controlling a system's high-side pressure during low ambient conditions...
High superheat and low discharge pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
('Y' and 'C') and ('G' and 'C')
High superheat and low discharge pressure

14. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An open internal overload protector
The discharge pressure increases and the amperage increases
High suction pressure and low superheat

15. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Both technicians are incorrect
An open internal overload protector
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

16. 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
An uninsulated TXV sensing bulb
High superheat and low discharge pressure
Technician B
Contains a solenoid coil and one or more sets of contacts

17. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
Whenever necessary
Clean the condenser coil
Flooding the condenser - cycling condenser fans - and dampering condenser air

18. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Both technicians are correct
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase in suction pressure and an increase in discharge pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

19. 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
Technician B
Bad compressor valve
An uninsulated suction line and a restricted metering device
'G' to 'C'

20. What component is most often the cause of a start capacitor failure...
Both technicians are incorrect
A sensing bulb improperly connected to the suction line
Low voltage and a faulty start relay
A start relay

21. 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
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
The discharge pressure increases and the amperage increases
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

22. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
A blown fuse
A sensing bulb improperly connected to the suction line
A start relay

23. What causes the automatic expansion valve to close...
An increase in low-side pressure
A plugged filter drier
An overcharged system
The low-side pressure will decrease and the evaporator coil will be partially frosted

24. What are the operating pressures of an oil pressure safety switch...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The oil pump pressure and the crankcase pressure
3 psig
A restricted metering device

25. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
110-120
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The superheat increases and the subcooling decreases

26. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Current in the compressor circuit
An open internal overload protector
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
High suction pressure and low superheat

27. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The external equalizer could be plugged
The discharge pressure increases and the amperage increases
High suction pressure and low superheat
'G' to 'C'

28. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Bad compressor valve
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Low discharge pressure - high suction pressure - and low amp draw
20 to 30

29. Air filters should be replaced...
Whenever necessary
3 psig
An increase in suction pressure and an increase in discharge pressure
Rise more than normal

30. A customer calls with an insufficient cooling complaint on a 90
An increase of air leakage from ductwork
A bad thermostat
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B

31. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
High suction pressure and low superheat
Technician B

32. A hard-start kit consists of...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A start capacitor and a solid-state relay
Partially frosted evaporator and high superheat
A plugged filter drier

33. A liquid-charged TXV bulb will...
An uninsulated suction line and a restricted metering device
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are incorrect
Always have some liquid present in the bulb and diaphragm

34. 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
Contains a solenoid coil and one or more sets of contacts
The internal overload is opened
Low discharge pressure - high suction pressure - and low amp draw

35. 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
Whenever necessary
Technician B
'G' to 'C'

36. What are two common symptoms of refrigerant leaks in an air conditioning system...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Bad compressor valve
Partially frosted evaporator and high superheat
Short cycling and insufficient dehumidification

37. Which of the following can cause excessive subcooling...
Bad compressor valve
An overcharged system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An undercharged system+insufficient airflow over the evaporator coil

38. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small
A start capacitor and a solid-state relay
Low discharge pressure - high suction pressure - and low amp draw

39. 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
An open internal overload protector
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Short cycling and insufficient dehumidification
Technician B

40. What is the common cause of a compressor burnout...
50-65
A plugged filter drier
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Both technicians are incorrect

41. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
('Y' and 'C') and ('G' and 'C')
A low refrigerant charge
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician A

42. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A defective circuit breaker
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
20 to 30

43. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Whenever necessary
Run with high head and high suction pressure
Broken rings+broken valves+seized bearings

44. 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
Technician B
The system has been overcharged+The system has air trapped in the condenser
Both technicians are incorrect
Technician A

45. 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
Lack of airflow
Evaporator and compressor
Technician B
An acid-core suction line drier

46. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
Technician B
A start capacitor and a solid-state relay
A start relay

47. Which of the following is a possible cause for a compressor to overheat...
A defective circuit breaker
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A low refrigerant charge
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

48. What are the operating pressures of an oil pressure safety switch...
Contains a solenoid coil and one or more sets of contacts
The oil pump pressure and the crankcase pressure
50-65
A bad thermostat

49. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The internal overload is opened
Technician B
Technician A is correct

50. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A start capacitor and a solid-state relay
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are correct
Low discharge pressure - high suction pressure - and low amp draw