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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. A system that is operating with a clear sight glass shows...
Technician B
The sight glass is full of liquid+the sight glass is full of gas
'G' to 'C'
Technician B

2. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
A start capacitor and a solid-state relay
Always have some liquid present in the bulb and diaphragm
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

3. 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 superheat
Low voltage and a faulty start relay
The oil pump pressure and the crankcase pressure
Clean the condenser coil

4. A customer calls with an insufficient cooling complaint on a 90
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
Lack of airflow

5. A hard-start kit consists of...
The external equalizer could be plugged
The discharge pressure increases and the amperage increases
A start capacitor and a solid-state relay
The internal overload is opened

6. 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 increase in low-side pressure
Low voltage and a faulty start relay
A restricted metering device

7. What are common methods that are used for leak-testing a system...
An undercharged system+insufficient airflow over the evaporator coil
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A vacuum test+oil traces around fittings+soap bubble solution

8. What causes the automatic expansion valve to close...
3 psig
High superheat and low discharge pressure
An uninsulated TXV sensing bulb
An increase in low-side pressure

9. 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
Clean the condenser coil
Low voltage and a faulty start relay
Both technicians are incorrect
A blown fuse

10. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
50-65
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An undercharge and low ambient conditions
High suction pressure and low superheat

11. Which of the following can cause excessive subcooling...
The internal overload is opened
An overcharged system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Rise more than normal

12. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An overcharged system
Technician B
A sensing bulb improperly connected to the suction line

13. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
Bad compressor valve
A sensing bulb improperly connected to the suction line
Whenever necessary

14. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A missing air filter+improper rotation of the indoor blower+blower too small
Bad compressor valve
Rise more than normal
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

15. Which of the following is a common cause of an excessively low superheat on a TXV system...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A sensing bulb improperly connected to the suction line
('Y' and 'C') and ('G' and 'C')
Evaporator and compressor

16. What component is most often the cause of a start capacitor failure...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B
A defective circuit breaker
A start relay

17. The best description of a relay would be...
An overcharged system
Contains a solenoid coil and one or more sets of contacts
An open internal overload protector
Clean the condenser coil

18. 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
Current in the compressor circuit
Technician B
An undercharge and low ambient conditions
A start relay

19. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Evaporator and compressor
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
'G' to 'C'
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

20. Why is it unsafe to operate an air conditioning system with a low charge...
Both technicians are incorrect
'G' to 'C'
A start capacitor and a solid-state relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

21. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B
Run with high head and high suction pressure
Both technicians are incorrect

22. 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 internal overload is opened
The oil pump pressure and the crankcase pressure
Technician B
High superheat and low discharge pressure

23. 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
The oil pump pressure and the crankcase pressure
Technician A
50-65

24. Which of the following will cause excessive discharge pressures on an air conditioning system...
20 to 30
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Evaporator and compressor
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

25. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The external equalizer could be plugged
Whenever necessary
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

26. A liquid-charged TXV bulb will...
Broken rings+broken valves+seized bearings
A blown fuse
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

27. What component is most often the cause of a start capacitor failure...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The system has been overcharged+The system has air trapped in the condenser
A start relay
A vacuum test+oil traces around fittings+soap bubble solution

28. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A missing air filter+improper rotation of the indoor blower+blower too small
High suction pressure and low superheat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A low refrigerant charge

29. What is the purpose of a CPR valve...
Lack of airflow
It is used to control refrigerant pressure in the compressor crankcase
110-120
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

30. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Short cycling and insufficient dehumidification
Low superheat
Technician B

31. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The oil pump pressure and the crankcase pressure
An acid-core suction line drier
Short cycling and insufficient dehumidification
Low discharge pressure - high suction pressure - and low amp draw

32. When using a vapor-charged TXV bulb - it is necessary to have...
A start relay
A start capacitor and a solid-state relay
An uninsulated TXV sensing bulb
The sensing bulb at a lower temperature than the valve body

33. 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
It keeps a constant superheat in the evaporator
An uninsulated suction line and a restricted metering device
Technician A is correct
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

34. 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...
Technician B
High superheat and low discharge pressure
A sensing bulb improperly connected to the suction line
A blown fuse

35. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The low-side pressure will decrease and the evaporator coil will be partially frosted
An acid-core suction line drier
A missing air filter+improper rotation of the indoor blower+blower too small

36. Air filters should be replaced...
Whenever necessary
('Y' and 'C') and ('G' and 'C')
Technician B
A restricted metering device

37. 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
Low discharge pressure - high suction pressure - and low amp draw
It would cause the low-side pressure to decrease
Broken rings+broken valves+seized bearings

38. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The discharge pressure increases and the amperage increases
A defective circuit breaker
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

39. What is the purpose of the TXV...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It keeps a constant superheat in the evaporator
The system has been overcharged+The system has air trapped in the condenser

40. 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
A restricted metering device
Technician B
A start capacitor and a solid-state relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

41. Air filters should be replaced...
A blown fuse
Technician B
Whenever necessary
Bad compressor valve

42. What is the purpose of an EPR valve...
110-120
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A start capacitor and a solid-state relay
Flooding the condenser - cycling condenser fans - and dampering condenser air

43. What is the purpose of an EPR valve...
A vacuum test+oil traces around fittings+soap bubble solution
Technician A
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

44. What problem or problems can cause low discharge and suction pressure...
The external equalizer could be plugged
An undercharged system+insufficient airflow over the evaporator coil
The superheat increases and the subcooling decreases
Technician B

45. What are common methods that are used for leak-testing a system...
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
Technician B
It is used to control refrigerant pressure in the compressor crankcase

46. What causes the automatic expansion valve to close...
An overcharged system
An increase in low-side pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An uninsulated suction line and a restricted metering device

47. Which of the following is a common cause of an excessively low superheat on a TXV system...
It keeps a constant superheat in the evaporator
A vacuum test+oil traces around fittings+soap bubble solution
A sensing bulb improperly connected to the suction line
Both technicians are incorrect

48. 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
An open internal overload protector
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The low-side pressure will decrease and the evaporator coil will be partially frosted
Lack of airflow

49. The internal overload of an air conditioning compressor senses winding temperature and...
Technician B
An increase in low-side pressure
Technician B
Current in the compressor circuit

50. 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
An overcharged system
An overcharged system
Both technicians are incorrect
A bad thermostat