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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. When using a vapor-charged TXV bulb - it is necessary to have...
An undercharge and low ambient conditions
A plugged filter drier
The sensing bulb at a lower temperature than the valve body
Low discharge pressure - high suction pressure - and low amp draw

2. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Both technicians are incorrect
An open internal overload protector
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Condenser fans operating during a low ambient condition and a low suction pressure

3. 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
A start relay
Run with high head and high suction pressure
Both technicians are incorrect

4. 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...
Evaporator and compressor
High superheat and low discharge pressure
Broken rings+broken valves+seized bearings
Technician A

5. A liquid-charged TXV bulb will...
A low refrigerant charge
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A start relay
Always have some liquid present in the bulb and diaphragm

6. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
An undercharged system+insufficient airflow over the evaporator coil
A plugged filter drier

7. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
('Y' and 'C') and ('G' and 'C')
A dirty condenser - recirculation of condenser air - and a defective condenser fan

8. What are the operating pressures of an oil pressure safety switch...
It keeps a constant superheat in the evaporator
The superheat will increase and the low-side pressure will decrease
The oil pump pressure and the crankcase pressure
An uninsulated TXV sensing bulb

9. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Bad compressor valve
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
110-120

10. 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
Broken rings+broken valves+seized bearings
It is used to control refrigerant pressure in the compressor crankcase
A start capacitor and a solid-state relay

11. 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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12. The internal overload of an air conditioning compressor senses winding temperature and...
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
Current in the compressor circuit
Both technicians are incorrect

13. 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
An undercharge and low ambient conditions
Technician B
Low discharge pressure - high suction pressure - and low amp draw

14. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
A low refrigerant charge
An increase of air leakage from ductwork
An acid-core suction line drier

15. 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
Clean the condenser coil
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

16. A hard-start kit for an air conditioning system...
The discharge pressure increases and the amperage increases
The sight glass is full of liquid+the sight glass is full of gas
3 psig
Increases starting torque

17. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A bad thermostat
The sight glass is full of liquid+the sight glass is full of gas
50-65
20 to 30

18. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The discharge pressure increases and the amperage increases
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Contains a solenoid coil and one or more sets of contacts
Low discharge pressure - high suction pressure - and low amp draw

19. Which of the following can cause low superheat in a TXV system...
'G' to 'C'
An uninsulated TXV sensing bulb
The superheat will increase and the low-side pressure will decrease
Run with high head and high suction pressure

20. Why is it unsafe to operate an air conditioning system with a low charge...
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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A plugged filter drier

21. What are the symptoms of an air conditioning system that has a low charge...
The discharge pressure increases and the amperage increases
The low-side pressure will decrease and the evaporator coil will be partially frosted
It keeps a constant superheat in the evaporator
Short cycling and insufficient dehumidification

22. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A missing air filter+improper rotation of the indoor blower+blower too small
An overcharged system

23. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Low discharge pressure - high suction pressure - and low amp draw
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An undercharge and low ambient conditions

24. What problem can cause an increase of discharge pressure and an increase of suction pressure...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An overcharged system
Contains a solenoid coil and one or more sets of contacts
Always have some liquid present in the bulb and diaphragm

25. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Technician A is correct
Lack of airflow
A blown fuse
('Y' and 'C') and ('G' and 'C')

26. What problem or problems can cause low discharge and suction pressure...
Both technicians are correct
The low-side pressure will decrease and the evaporator coil will be partially frosted
The discharge pressure increases and the amperage increases
An undercharged system+insufficient airflow over the evaporator coil

27. 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
Lack of airflow
Partially frosted evaporator and high superheat
Low voltage and a faulty start relay
Technician B

28. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A sensing bulb improperly connected to the suction line
Technician A is correct
A missing air filter+improper rotation of the indoor blower+blower too small
An undercharge and low ambient conditions

29. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Technician A
The sensing bulb at a lower temperature than the valve body
An increase in suction pressure and an increase in discharge pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser

30. 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
3 psig
The oil pump pressure and the crankcase pressure
Increases starting torque

31. A compressor having tight bearings would cause the current value to...
Rise more than normal
A low refrigerant charge
An overcharged system
The low-side pressure will decrease and the evaporator coil will be partially frosted

32. Which of the following can cause excessive subcooling...
The superheat will increase and the low-side pressure will decrease
An overcharged system
Always have some liquid present in the bulb and diaphragm
An increase in low-side pressure

33. A commercial customer calls on a 90
An overcharged system
An open internal overload protector
The system has been overcharged+The system has air trapped in the condenser
The sight glass is full of liquid+the sight glass is full of gas

34. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An increase of air leakage from ductwork
Both technicians are incorrect
It would cause the low-side pressure to decrease
The superheat increases and the subcooling decreases

35. 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
Technician B
Run with high head and high suction pressure
Technician B

36. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A blown fuse
The external equalizer could be plugged
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Whenever necessary

37. 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 low-side pressure will decrease and the evaporator coil will be partially frosted
Current in the compressor circuit
A bad thermostat
Both technicians are incorrect

38. 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
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An overcharged system

39. A system that is operating with a clear sight glass shows...
Technician B
Broken rings+broken valves+seized bearings
The sight glass is full of liquid+the sight glass is full of gas
A defective circuit breaker

40. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
'G' to 'C'
Low discharge pressure - high suction pressure - and low amp draw
A defective circuit breaker
An uninsulated suction line and a restricted metering device

41. Insufficient airflow can be caused by...
The superheat will increase and the low-side pressure will decrease
Whenever necessary
Technician B
An increase of air leakage from ductwork

42. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An increase in suction pressure and an increase in discharge pressure
Current in the compressor circuit
A start relay
The superheat increases and the subcooling decreases

43. 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
Technician B
Low superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A defective circuit breaker

44. 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
A defective circuit breaker
Bad compressor valve
An overcharged system

45. What are the symptoms of an air conditioning system that has a low charge...
110-120
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Clean the condenser coil
The low-side pressure will decrease and the evaporator coil will be partially frosted

46. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
An increase in suction pressure and an increase in discharge pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

47. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Technician B
Partially frosted evaporator and high superheat
It would cause the low-side pressure to decrease
Both technicians are incorrect

48. A customer calls with an insufficient cooling complaint on a 90
Technician B
Rise more than normal
Both technicians are incorrect
An uninsulated suction line and a restricted metering device

49. A customer calls with an insufficient cooling complaint on a 90
Whenever necessary
The superheat will increase and the low-side pressure will decrease
An undercharged system+insufficient airflow over the evaporator coil
Technician B

50. What are the symptoms of a TXV air conditioning system if it has lost its charge...
50-65
The sensing bulb at a lower temperature than the valve body
The superheat will increase and the low-side pressure will decrease
20 to 30