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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 restricted air filter in an air conditioning system can be identified by...
Low superheat
The discharge pressure increases and the amperage increases
An uninsulated suction line and a restricted metering device
A vacuum test+oil traces around fittings+soap bubble solution

2. What are two common symptoms of refrigerant leaks in an air conditioning system...
An increase of air leakage from ductwork
Partially frosted evaporator and high superheat
The external equalizer could be plugged
An open internal overload protector

3. 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
An undercharge and low ambient conditions
Both technicians are incorrect
Technician B
Current in the compressor circuit

4. 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
Partially frosted evaporator and high superheat
Current in the compressor circuit
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician A is correct

5. 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
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Both technicians are correct
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

6. What is the purpose of the TXV...
A sensing bulb improperly connected to the suction line
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Low superheat
It keeps a constant superheat in the evaporator

7. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
50-65
Low superheat

8. 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 vacuum test+oil traces around fittings+soap bubble solution
Technician A is correct
20 to 30

9. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
Current in the compressor circuit
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A blown fuse

10. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Technician B
It would cause the low-side pressure to decrease
The external equalizer could be plugged
Increases starting torque

11. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Condenser fans operating during a low ambient condition and a low suction pressure
'G' to 'C'
An increase in suction pressure and an increase in discharge pressure
High superheat and low discharge pressure

12. The internal overload of an air conditioning compressor senses winding temperature and...
20 to 30
Low voltage and a faulty start relay
Contains a solenoid coil and one or more sets of contacts
Current in the compressor circuit

13. 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 thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
110-120
A blown fuse
Both technicians are correct

14. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
The system has been overcharged+The system has air trapped in the condenser
An uninsulated TXV sensing bulb
Evaporator and compressor

15. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
'G' to 'C'
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Broken rings+broken valves+seized bearings
The superheat increases and the subcooling decreases

16. Which of the following can cause excessive subcooling...
Current in the compressor circuit
Technician B
The superheat will increase and the low-side pressure will decrease
An overcharged system

17. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Evaporator and compressor

18. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
The oil pump pressure and the crankcase pressure
Lack of airflow
Both technicians are correct
It would cause the low-side pressure to decrease

19. A hard-start kit consists of...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
High superheat and low discharge pressure
The superheat increases and the subcooling decreases
A start capacitor and a solid-state relay

20. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A start relay
Both technicians are correct
Contains a solenoid coil and one or more sets of contacts
Flooding the condenser - cycling condenser fans - and dampering condenser air

21. 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
The superheat will increase and the low-side pressure will decrease
Both technicians are correct
110-120

22. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
Increases starting torque
A missing air filter+improper rotation of the indoor blower+blower too small
A sensing bulb improperly connected to the suction line

23. A hard-start kit for an air conditioning system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Increases starting torque
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

24. Which of the following can cause excessive subcooling...
Technician A is correct
An overcharged system
Condenser fans operating during a low ambient condition and a low suction pressure
It is used to control refrigerant pressure in the compressor crankcase

25. A technician arrives on the job and the customer complains that there is no cooling on his rooftop unit. Troubleshooting the system - the technician finds that the compressor is faulty. He notices that there is another faulty compressor laying next t
Increases starting torque
Broken rings+broken valves+seized bearings
The sight glass is full of liquid+the sight glass is full of gas
A restricted metering device

26. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A defective circuit breaker
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
110-120

27. Which of the following is a common cause of an excessively low superheat on a TXV system...
The system has been overcharged+The system has air trapped in the condenser
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An undercharge and low ambient conditions
A sensing bulb improperly connected to the suction line

28. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
The system has been overcharged+The system has air trapped in the condenser
Low superheat
An acid-core suction line drier
Partially frosted evaporator and high superheat

29. What are two problems that can cause an air conditioning system to have an excessively high superheat...
3 psig
A low refrigerant charge
An uninsulated suction line and a restricted metering device
Broken rings+broken valves+seized bearings

30. The temperature range of the suction line from an air conditioning system should be...
A sensing bulb improperly connected to the suction line
The superheat will increase and the low-side pressure will decrease
50-65
An increase in low-side pressure

31. 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
A blown fuse
High suction pressure and low superheat
A start capacitor and a solid-state relay

32. 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...
It keeps a constant superheat in the evaporator
High superheat and low discharge pressure
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan

33. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A low refrigerant charge
Broken rings+broken valves+seized bearings
The discharge pressure increases and the amperage increases

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...
The system has been overcharged+The system has air trapped in the condenser
Technician A
A blown fuse
An uninsulated suction line and a restricted metering device

35. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Rise more than normal

36. 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
Short cycling and insufficient dehumidification
A defective circuit breaker
Technician A is correct
Lack of airflow

37. 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
50-65
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B

38. What are the symptoms of an air conditioning system that has a low charge...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Both technicians are correct
Both technicians are incorrect
It keeps a constant superheat in the evaporator

39. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Technician A
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An overcharged system
Partially frosted evaporator and high superheat

40. 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
Both technicians are correct
Contains a solenoid coil and one or more sets of contacts
Short cycling and insufficient dehumidification

41. 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 oil pump pressure and the crankcase pressure
High superheat and low discharge pressure
A low refrigerant charge
A vacuum test+oil traces around fittings+soap bubble solution

42. What is the purpose of the TXV...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Low voltage and a faulty start relay
It keeps a constant superheat in the evaporator
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

43. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An increase in low-side pressure
Bad compressor valve
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The sensing bulb at a lower temperature than the valve body

44. A liquid-charged TXV bulb will...
The sight glass is full of liquid+the sight glass is full of gas
Always have some liquid present in the bulb and diaphragm
Low superheat
Current in the compressor circuit

45. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
An undercharge and low ambient conditions
Run with high head and high suction pressure

46. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
Technician A is correct
A bad thermostat
A plugged filter drier

47. What problem or problems can cause low discharge and suction pressure...
Current in the compressor circuit
'G' to 'C'
An undercharged system+insufficient airflow over the evaporator coil
Evaporator and compressor

48. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B

49. 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
A low refrigerant charge
Low superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser

50. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Bad compressor valve
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A vacuum test+oil traces around fittings+soap bubble solution