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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. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Partially frosted evaporator and high superheat
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Rise more than normal
Increases starting torque

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
A missing air filter+improper rotation of the indoor blower+blower too small
A plugged filter drier
'G' to 'C'
A defective circuit breaker

3. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
A vacuum test+oil traces around fittings+soap bubble solution
Always have some liquid present in the bulb and diaphragm
Lack of airflow

4. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Low discharge pressure - high suction pressure - and low amp draw
The oil pump pressure and the crankcase pressure
An overcharged system
A start capacitor and a solid-state relay

5. 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
An increase in low-side pressure
Broken rings+broken valves+seized bearings
Technician A is correct

6. When using a vapor-charged TXV bulb - it is necessary to have...
Increases starting torque
An increase in suction pressure and an increase in discharge pressure
The sensing bulb at a lower temperature than the valve body
An acid-core suction line drier

7. Which of the following can cause low superheat in a TXV system...
Evaporator and compressor
An uninsulated TXV sensing bulb
An increase in suction pressure and an increase in discharge pressure
A sensing bulb improperly connected to the suction line

8. What are the symptoms of a TXV air conditioning system if it has lost its charge...
High superheat and low discharge pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The superheat will increase and the low-side pressure will decrease
Evaporator and compressor

9. 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...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Low voltage and a faulty start relay
Run with high head and high suction pressure
An increase in low-side pressure

10. 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...
Short cycling and insufficient dehumidification
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
The internal overload is opened

11. 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
A low refrigerant charge
An undercharged system+insufficient airflow over the evaporator coil
A bad thermostat
A blown fuse

12. 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
High superheat and low discharge pressure
The discharge pressure increases and the amperage increases
Both technicians are correct

13. The best description of a relay would be...
A low refrigerant charge
Contains a solenoid coil and one or more sets of contacts
An overcharged system
Technician B

14. Which of the following could be the cause for a system's discharge and suction pressure being low...
3 psig
Current in the compressor circuit
A low refrigerant charge
A restricted metering device

15. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
It would cause the low-side pressure to decrease
Technician B
Technician B
A plugged filter drier

16. 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
The internal overload is opened
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase in suction pressure and an increase in discharge pressure

17. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
It keeps a constant superheat in the evaporator
50-65
110-120
Run with high head and high suction pressure

18. A restricted air filter in an air conditioning system can be identified by...
The internal overload is opened
Bad compressor valve
The oil pump pressure and the crankcase pressure
Low superheat

19. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
An increase of air leakage from ductwork
20 to 30
High superheat and low discharge pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser

20. 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
A blown fuse
Both technicians are correct
20 to 30
A start relay

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
A missing air filter+improper rotation of the indoor blower+blower too small
20 to 30
Technician B

22. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A blown fuse
High superheat and low discharge pressure
An uninsulated suction line and a restricted metering device
The superheat increases and the subcooling decreases

23. A commercial customer calls on a 90
Technician A
A defective circuit breaker
The low-side pressure will decrease and the evaporator coil will be partially frosted
The system has been overcharged+The system has air trapped in the condenser

24. A compressor having tight bearings would cause the current value to...
The sensing bulb at a lower temperature than the valve body
110-120
Rise more than normal
A restricted metering device

25. 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 plugged filter drier
Technician B
Rise more than normal

26. 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
An increase in suction pressure and an increase in discharge pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are correct

27. A hard-start kit consists of...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A vacuum test+oil traces around fittings+soap bubble solution
Technician B
A start capacitor and a solid-state relay

28. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
50-65
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An acid-core suction line drier
An undercharged system+insufficient airflow over the evaporator coil

29. Air filters should be replaced...
Always have some liquid present in the bulb and diaphragm
('Y' and 'C') and ('G' and 'C')
Whenever necessary
50-65

30. 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 blown fuse
A defective circuit breaker
Current in the compressor circuit
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

31. What is the purpose of an EPR valve...
Contains a solenoid coil and one or more sets of contacts
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Condenser fans operating during a low ambient condition and a low suction pressure
Low superheat

32. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An acid-core suction line drier
A missing air filter+improper rotation of the indoor blower+blower too small
An undercharge and low ambient conditions
Technician B

33. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
3 psig
Technician B
Current in the compressor circuit

34. 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
A start relay
Technician A is correct
An undercharged system+insufficient airflow over the evaporator coil

35. 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
It is used to control refrigerant pressure in the compressor crankcase
50-65
A start capacitor and a solid-state relay

36. Which of the following will cause excessive discharge pressures on an air conditioning system...
A defective circuit breaker
('Y' and 'C') and ('G' and 'C')
An overcharged system
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

37. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Clean the condenser coil
An acid-core suction line drier
An overcharged system
An increase in suction pressure and an increase in discharge pressure

38. Insufficient airflow can be caused by...
An undercharged system+insufficient airflow over the evaporator coil
An increase of air leakage from ductwork
Technician B
It keeps a constant superheat in the evaporator

39. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Bad compressor valve
110-120
('Y' and 'C') and ('G' and 'C')

40. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A start relay
'G' to 'C'
Low superheat
A missing air filter+improper rotation of the indoor blower+blower too small

41. 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
An undercharged system+insufficient airflow over the evaporator coil
Low voltage and a faulty start relay
The system has been overcharged+The system has air trapped in the condenser
Technician A

42. When using a vapor-charged TXV bulb - it is necessary to have...
A bad thermostat
Increases starting torque
An uninsulated TXV sensing bulb
The sensing bulb at a lower temperature than the valve body

43. What causes the automatic expansion valve to close...
An open internal overload protector
An increase in low-side pressure
Both technicians are incorrect
Short cycling and insufficient dehumidification

44. A liquid-charged TXV bulb will...
Broken rings+broken valves+seized bearings
The internal overload is opened
Flooding the condenser - cycling condenser fans - and dampering condenser air
Always have some liquid present in the bulb and diaphragm

45. What component is most often the cause of a start capacitor failure...
The sight glass is full of liquid+the sight glass is full of gas
Always have some liquid present in the bulb and diaphragm
A start relay
Contains a solenoid coil and one or more sets of contacts

46. What are common methods that are used for leak-testing a system...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A plugged filter drier
Broken rings+broken valves+seized bearings
A vacuum test+oil traces around fittings+soap bubble solution

47. 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
Lack of airflow
110-120
Bad compressor valve

48. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Lack of airflow
A vacuum test+oil traces around fittings+soap bubble solution
The superheat increases and the subcooling decreases
Flooding the condenser - cycling condenser fans - and dampering condenser air

49. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
A blown fuse
The superheat will increase and the low-side pressure will decrease
The oil pump pressure and the crankcase pressure

50. 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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