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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. Which of the following can cause low superheat in a TXV system...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A bad thermostat
Evaporator and compressor
An uninsulated TXV sensing bulb

2. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
An open internal overload protector
Technician B
High suction pressure and low superheat
Increases starting torque

3. Which of the following can cause excessive subcooling...
Evaporator and compressor
Technician B
An overcharged system
An increase in suction pressure and an increase in discharge pressure

4. 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
Technician A is correct
Technician A
An undercharged system+insufficient airflow over the evaporator coil
Lack of airflow

5. When using a vapor-charged TXV bulb - it is necessary to have...
An open internal overload protector
The sensing bulb at a lower temperature than the valve body
Increases starting torque
An undercharged system+insufficient airflow over the evaporator coil

6. A system that uses a thermal electric expansion valve...
Low voltage and a faulty start relay
110-120
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

7. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An open internal overload protector
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The discharge pressure increases and the amperage increases
Current in the compressor circuit

8. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
A blown fuse
('Y' and 'C') and ('G' and 'C')
Low discharge pressure - high suction pressure - and low amp draw
20 to 30

9. What is the common cause of a compressor burnout...
An undercharge and low ambient conditions
Bad compressor valve
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B

10. 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
Partially frosted evaporator and high superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Low superheat

11. A customer calls and says that her air conditioning system is not cooling properly. Upon arrival - a technician notices that the suction line and compressor have frost buildup. Technician A says that the problem is probably a low charge. Technician B
Technician B
It is used to control refrigerant pressure in the compressor crankcase
The superheat increases and the subcooling decreases
An uninsulated suction line and a restricted metering device

12. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Rise more than normal
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Low discharge pressure - high suction pressure - and low amp draw
Technician B

13. A compressor having tight bearings would cause the current value to...
Technician B
A sensing bulb improperly connected to the suction line
Rise more than normal
Whenever necessary

14. 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
Technician A is correct
Technician B
A plugged filter drier
A vacuum test+oil traces around fittings+soap bubble solution

15. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Technician A
3 psig
Technician A is correct
The discharge pressure increases and the amperage increases

16. 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
50-65
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The system has been overcharged+The system has air trapped in the condenser

17. Which of the following can cause excessive subcooling...
Both technicians are incorrect
It keeps a constant superheat in the evaporator
An overcharged system
Technician B

18. What type of problems can be caused by an oversized air conditioning system...
Partially frosted evaporator and high superheat
Clean the condenser coil
Short cycling and insufficient dehumidification
Both technicians are incorrect

19. A hard-start kit for an air conditioning system...
Increases starting torque
A restricted metering device
Partially frosted evaporator and high superheat
Technician B

20. Which of the following is a common cause of an excessively low superheat on a TXV system...
A blown fuse
Flooding the condenser - cycling condenser fans - and dampering condenser air
A sensing bulb improperly connected to the suction line
An acid-core suction line drier

21. 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 overcharged system
'G' to 'C'
Both technicians are incorrect
The low-side pressure will decrease and the evaporator coil will be partially frosted

22. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A vacuum test+oil traces around fittings+soap bubble solution
Evaporator and compressor
An increase in low-side pressure
110-120

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...
The internal overload is opened
An overcharged system
The sensing bulb at a lower temperature than the valve body
Increases starting torque

24. What are the symptoms of an air conditioning system that has a low charge...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Low voltage and a faulty start relay
The low-side pressure will decrease and the evaporator coil will be partially frosted
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

25. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Flooding the condenser - cycling condenser fans - and dampering condenser air
110-120
The superheat will increase and the low-side pressure will decrease
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

26. 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
Technician B
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
A start relay

27. What are the operating pressures of an oil pressure safety switch...
An increase in low-side pressure
A restricted metering device
The oil pump pressure and the crankcase pressure
Clean the condenser coil

28. A customer calls and says that her air conditioning system is not cooling properly. Upon arrival - a technician notices that the suction line and compressor have frost buildup. Technician A says that the problem is probably a low charge. Technician B
Bad compressor valve
An increase in suction pressure and an increase in discharge pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B

29. Superheat is found in an air conditioning system in the...
Low voltage and a faulty start relay
The superheat increases and the subcooling decreases
Evaporator and compressor
It would cause the low-side pressure to decrease

30. 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
Increases starting torque
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Both technicians are incorrect
An uninsulated suction line and a restricted metering device

31. 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
Both technicians are correct
A defective circuit breaker
The internal overload is opened
Both technicians are incorrect

32. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
It keeps a constant superheat in the evaporator
110-120
Whenever necessary
3 psig

33. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
Both technicians are incorrect
The internal overload is opened
High suction pressure and low superheat

34. A customer calls and complains that her high-efficiency air conditioning system is operating - but is not cooling properly. Further investigation shows that the system is using a TXV type of metering device. A subcooling check shows that the system a
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The external equalizer could be plugged
An undercharged system+insufficient airflow over the evaporator coil

35. 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...
Partially frosted evaporator and high superheat
The superheat increases and the subcooling decreases
Both technicians are incorrect
High superheat and low discharge pressure

36. Which of the following is a possible cause for a compressor to overheat...
Technician A is correct
Broken rings+broken valves+seized bearings
A low refrigerant charge
Low superheat

37. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The sight glass is full of liquid+the sight glass is full of gas
A plugged filter drier
The oil pump pressure and the crankcase pressure

38. 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
A restricted metering device
High superheat and low discharge pressure
110-120
Technician B

39. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An increase in low-side pressure
The superheat increases and the subcooling decreases
Always have some liquid present in the bulb and diaphragm
Partially frosted evaporator and high superheat

40. A hard-start kit for an air conditioning system...
Technician B
Increases starting torque
'G' to 'C'
Run with high head and high suction pressure

41. 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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42. 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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43. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The superheat will increase and the low-side pressure will decrease
Increases starting torque
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The system has been overcharged+The system has air trapped in the condenser

44. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
An undercharge and low ambient conditions
A start capacitor and a solid-state relay
The system has been overcharged+The system has air trapped in the condenser

45. 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
A low refrigerant charge
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

46. Which of the following could be the cause for a system's discharge and suction pressure being low...
Lack of airflow
A restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

47. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

48. 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
'G' to 'C'
A sensing bulb improperly connected to the suction line
It is used to control refrigerant pressure in the compressor crankcase
Technician B

49. What are two common symptoms of a rooftop air conditioning system that operates with a reverse-acting high-pressure control stuck in the closed position...
Condenser fans operating during a low ambient condition and a low suction pressure
An increase of air leakage from ductwork
Technician B
Run with high head and high suction pressure

50. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Flooding the condenser - cycling condenser fans - and dampering condenser air
It is used to control refrigerant pressure in the compressor crankcase
Short cycling and insufficient dehumidification