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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...
Technician B
The superheat increases and the subcooling decreases
A bad thermostat
The sensing bulb at a lower temperature than the valve body

2. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A defective circuit breaker
An acid-core suction line drier
Technician B
High suction pressure and low superheat

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
Technician A
Short cycling and insufficient dehumidification
A bad thermostat
The oil pump pressure and the crankcase pressure

4. The best description of a relay would be...
Both technicians are incorrect
A missing air filter+improper rotation of the indoor blower+blower too small
A sensing bulb improperly connected to the suction line
Contains a solenoid coil and one or more sets of contacts

5. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A blown fuse
An increase in suction pressure and an increase in discharge pressure
Evaporator and compressor
The system has been overcharged+The system has air trapped in the condenser

6. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The superheat will increase and the low-side pressure will decrease
Low discharge pressure - high suction pressure - and low amp draw
An overcharged system
Low superheat

7. 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
Both technicians are incorrect
Increases starting torque
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician A is correct

8. 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
'G' to 'C'
An open internal overload protector
A plugged filter drier
An uninsulated TXV sensing bulb

9. What problem can cause an increase of discharge pressure and an increase of suction pressure...
'G' to 'C'
('Y' and 'C') and ('G' and 'C')
An increase in suction pressure and an increase in discharge pressure
An overcharged system

10. What are two problems that can cause an air conditioning system to have an excessively high superheat...
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
An overcharged system
Whenever necessary

11. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Both technicians are correct
An acid-core suction line drier
A restricted metering device
A vacuum test+oil traces around fittings+soap bubble solution

12. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
An increase of air leakage from ductwork
Partially frosted evaporator and high superheat
An overcharged system

13. What is the common cause of a compressor burnout...
'G' to 'C'
The oil pump pressure and the crankcase pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An undercharged system+insufficient airflow over the evaporator coil

14. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
An overcharged system
A vacuum test+oil traces around fittings+soap bubble solution
The system has been overcharged+The system has air trapped in the condenser

15. Which of the following is a common cause of an excessively low superheat on a TXV system...
A defective circuit breaker
The external equalizer could be plugged
Always have some liquid present in the bulb and diaphragm
A sensing bulb improperly connected to the suction line

16. A commercial customer calls on a 90
An increase in low-side pressure
The system has been overcharged+The system has air trapped in the condenser
Lack of airflow
An increase in suction pressure and an increase in discharge pressure

17. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
Technician A
It keeps a constant superheat in the evaporator
Technician B

18. A compressor having tight bearings would cause the current value to...
The system has been overcharged+The system has air trapped in the condenser
Rise more than normal
The discharge pressure increases and the amperage increases
A defective circuit breaker

19. 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
Broken rings+broken valves+seized bearings
20 to 30
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

20. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The superheat increases and the subcooling decreases
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
110-120

21. 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
Both technicians are incorrect
Technician B
The sensing bulb at a lower temperature than the valve body

22. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
50-65
20 to 30
3 psig

23. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
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
The oil pump pressure and the crankcase pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser

24. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It would cause the low-side pressure to decrease
Contains a solenoid coil and one or more sets of contacts
The internal overload is opened
Bad compressor valve

25. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
Technician B
A low refrigerant charge
Evaporator and compressor

26. 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
3 psig
Bad compressor valve
Technician B
High superheat and low discharge pressure

27. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Both technicians are incorrect
The superheat will increase and the low-side pressure will decrease
An increase of air leakage from ductwork
An increase of air leakage from ductwork

28. 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...
An uninsulated suction line and a restricted metering device
The superheat increases and the subcooling decreases
The internal overload is opened
A sensing bulb improperly connected to the suction line

29. 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 defective circuit breaker
A plugged filter drier
Technician B
A sensing bulb improperly connected to the suction line

30. 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
It keeps a constant superheat in the evaporator
Clean the condenser coil
Clean the condenser coil
A bad thermostat

31. What component is most often the cause of a start capacitor failure...
A start relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A restricted metering device
Technician B

32. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
20 to 30
Flooding the condenser - cycling condenser fans - and dampering condenser air
Run with high head and high suction pressure
A sensing bulb improperly connected to the suction line

33. What problem or problems can cause low discharge and suction pressure...
It is used to control refrigerant pressure in the compressor crankcase
An undercharged system+insufficient airflow over the evaporator coil
Rise more than normal
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

34. What are the symptoms of an air conditioning system that has a low charge...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Clean the condenser coil
An increase in low-side pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted

35. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
An open internal overload protector
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
110-120
A start capacitor and a solid-state relay

36. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
Technician A is correct
Run with high head and high suction pressure
The superheat will increase and the low-side pressure will decrease

37. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician A
A defective circuit breaker
Technician B

38. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Lack of airflow
Lack of airflow
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

39. Which of the following can cause low superheat in a TXV system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An increase of air leakage from ductwork
The low-side pressure will decrease and the evaporator coil will be partially frosted
An uninsulated TXV sensing bulb

40. 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
A start capacitor and a solid-state relay
The superheat increases and the subcooling decreases
Low discharge pressure - high suction pressure - and low amp draw

41. 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
An uninsulated TXV sensing bulb
Clean the condenser coil
The superheat will increase and the low-side pressure will decrease

42. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
The sight glass is full of liquid+the sight glass is full of gas
Broken rings+broken valves+seized bearings
The superheat will increase and the low-side pressure will decrease

43. 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
Contains a solenoid coil and one or more sets of contacts
An overcharged system
The sensing bulb at a lower temperature than the valve body

44. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Short cycling and insufficient dehumidification
Flooding the condenser - cycling condenser fans - and dampering condenser air
Both technicians are incorrect
The sight glass is full of liquid+the sight glass is full of gas

45. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Both technicians are incorrect
Short cycling and insufficient dehumidification
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small

46. Which of the following could be the cause for a system's discharge and suction pressure being low...
Increases starting torque
A restricted metering device
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The superheat increases and the subcooling decreases

47. Which of the following is a common cause of an excessively low superheat on a TXV system...
A sensing bulb improperly connected to the suction line
Always have some liquid present in the bulb and diaphragm
A start capacitor and a solid-state relay
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

48. Which of the following will cause excessive discharge pressures on an air conditioning system...
A restricted metering device
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An overcharged system
An undercharge and low ambient conditions

49. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
50-65
A vacuum test+oil traces around fittings+soap bubble solution
Low superheat

50. Which of the following will cause excessive discharge pressures on an air conditioning system...
Low voltage and a faulty start relay
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
The superheat will increase and the low-side pressure will decrease

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NATE Air Conditioning Troubleshooting

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