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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 purpose of a CPR valve...
Always have some liquid present in the bulb and diaphragm
A start capacitor and a solid-state relay
It is used to control refrigerant pressure in the compressor crankcase
An overcharged system

2. 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 restricted metering device
An increase in suction pressure and an increase in discharge pressure
A defective circuit breaker

3. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A restricted metering device
Short cycling and insufficient dehumidification

4. What causes the automatic expansion valve to close...
110-120
An increase in low-side pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Whenever necessary

5. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
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
It is used to control refrigerant pressure in the compressor crankcase

6. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A restricted metering device
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

7. 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 start capacitor and a solid-state relay
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B

8. 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
Both technicians are incorrect
It is used to control refrigerant pressure in the compressor crankcase
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan

9. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
Clean the condenser coil
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Always have some liquid present in the bulb and diaphragm

10. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A defective circuit breaker
Clean the condenser coil
Low discharge pressure - high suction pressure - and low amp draw
High suction pressure and low superheat

11. A liquid-charged TXV bulb will...
A vacuum test+oil traces around fittings+soap bubble solution
50-65
The discharge pressure increases and the amperage increases
Always have some liquid present in the bulb and diaphragm

12. What is the purpose of an EPR valve...
A vacuum test+oil traces around fittings+soap bubble solution
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 system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

13. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
('Y' and 'C') and ('G' and 'C')
Low superheat
20 to 30
It is used to control refrigerant pressure in the compressor crankcase

14. What are the symptoms of an air conditioning system that has a low charge...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted
An uninsulated TXV sensing bulb
A start relay

15. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Run with high head and high suction pressure
Technician B
High suction pressure and low superheat
Rise more than normal

16. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Technician A
A blown fuse
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Run with high head and high suction pressure

17. What component is most often the cause of a start capacitor failure...
The superheat increases and the subcooling decreases
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A start relay
Increases starting torque

18. 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
The discharge pressure increases and the amperage increases
The low-side pressure will decrease and the evaporator coil will be partially frosted
The sight glass is full of liquid+the sight glass is full of gas

19. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
The superheat increases and the subcooling decreases
An undercharge and low ambient conditions
Always have some liquid present in the bulb and diaphragm

20. The temperature range of the suction line from an air conditioning system should be...
Technician B
A restricted metering device
50-65
An increase of air leakage from ductwork

21. What are common methods that are used for leak-testing a system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Clean the condenser coil
An increase in suction pressure and an increase in discharge pressure
A vacuum test+oil traces around fittings+soap bubble solution

22. 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
A sensing bulb improperly connected to the suction line
The discharge pressure increases and the amperage increases
Dirty condenser - bent condenser fins - and air recirculating over the condenser

23. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Low voltage and a faulty start relay
The superheat increases and the subcooling decreases
A restricted metering device
Technician A

24. 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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An uninsulated suction line and a restricted metering device

25. What causes the automatic expansion valve to close...
'G' to 'C'
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An increase in low-side pressure
Technician B

26. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
20 to 30
An increase in suction pressure and an increase in discharge pressure
It would cause the low-side pressure to decrease
An increase of air leakage from ductwork

27. 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
The sight glass is full of liquid+the sight glass is full of gas
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The superheat increases and the subcooling decreases
Technician B

28. 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...
The superheat will increase and the low-side pressure will decrease
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An uninsulated TXV sensing bulb
High superheat and low discharge pressure

29. Which of the following will cause excessive discharge pressures on an air conditioning system...
An increase in low-side pressure
A defective circuit breaker
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Run with high head and high suction pressure

30. A customer calls with an insufficient cooling complaint on a 90
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
50-65

31. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Technician A
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Both technicians are incorrect
A plugged filter drier

32. Why is it unsafe to operate an air conditioning system with a low charge...
The sensing bulb at a lower temperature than the valve body
The low-side pressure will decrease and the evaporator coil will be partially frosted
The sensing bulb at a lower temperature than the valve body
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

33. Superheat is found in an air conditioning system in the...
Both technicians are incorrect
A start capacitor and a solid-state relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Evaporator and compressor

34. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A bad thermostat
20 to 30
An open internal overload protector

35. What problem or problems can cause low discharge and suction pressure...
Technician B
Always have some liquid present in the bulb and diaphragm
Rise more than normal
An undercharged system+insufficient airflow over the evaporator coil

36. 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
An overcharged system
A bad thermostat
Low voltage and a faulty start relay
Technician B

37. 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...
It keeps a constant superheat in the evaporator
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A blown fuse
A vacuum test+oil traces around fittings+soap bubble solution

38. The temperature range of the suction line from an air conditioning system should be...
50-65
Clean the condenser coil
Technician B
A plugged filter drier

39. A hard-start kit consists of...
Lack of airflow
A start capacitor and a solid-state relay
Partially frosted evaporator and high superheat
A restricted metering device

40. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Short cycling and insufficient dehumidification
Condenser fans operating during a low ambient condition and a low suction pressure
A blown fuse
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

41. 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...
High superheat and low discharge pressure
A start capacitor and a solid-state relay
Condenser fans operating during a low ambient condition and a low suction pressure
Low voltage and a faulty start relay

42. 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...
The internal overload is opened
Bad compressor valve
A start capacitor and a solid-state relay
Condenser fans operating during a low ambient condition and a low suction pressure

43. A system that is operating with a clear sight glass shows...
A start relay
The sight glass is full of liquid+the sight glass is full of gas
A start capacitor and a solid-state relay
3 psig

44. 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
Both technicians are incorrect
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Condenser fans operating during a low ambient condition and a low suction pressure

45. Air filters should be replaced...
Whenever necessary
Increases starting torque
Technician B
Current in the compressor circuit

46. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Low discharge pressure - high suction pressure - and low amp draw
110-120
Lack of airflow
50-65

47. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
An increase in low-side pressure
It is used to control refrigerant pressure in the compressor crankcase
Run with high head and high suction pressure

48. What is the common cause of a compressor burnout...
Technician A is correct
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An overcharged system

49. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A plugged filter drier
A plugged filter drier
Both technicians are incorrect
An increase in suction pressure and an increase in discharge pressure

50. Which of the following will cause excessive discharge pressures on an air conditioning system...
20 to 30
The sensing bulb at a lower temperature than the valve body
An uninsulated TXV sensing bulb
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system