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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 uses a thermal electric expansion valve...
A bad thermostat
A vacuum test+oil traces around fittings+soap bubble solution
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

2. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Always have some liquid present in the bulb and diaphragm
An overcharged system
An undercharge and low ambient conditions
The internal overload is opened

3. Superheat is found in an air conditioning system in the...
Rise more than normal
Evaporator and compressor
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B

4. 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
Condenser fans operating during a low ambient condition and a low suction pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A blown fuse
Technician B

5. A customer calls and complains that her high-efficiency air conditioning system is operating - but is not cooling properly. Further investigation shows that the system is using a TXV type of metering device. A subcooling check shows that the system a
Broken rings+broken valves+seized bearings
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The superheat will increase and the low-side pressure will decrease
The external equalizer could be plugged

6. What is the purpose of a CPR valve...
Both technicians are correct
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase in suction pressure and an increase in discharge pressure
It is used to control refrigerant pressure in the compressor crankcase

7. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
An overcharged system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It is used to control refrigerant pressure in the compressor crankcase

8. What are two problems that can cause an air conditioning system to have an excessively high superheat...
The sensing bulb at a lower temperature than the valve body
An uninsulated suction line and a restricted metering device
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B

9. 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
Run with high head and high suction pressure
Technician B
An overcharged system
A blown fuse

10. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
3 psig
110-120
Always have some liquid present in the bulb and diaphragm

11. 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...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A blown fuse
Low voltage and a faulty start relay
Contains a solenoid coil and one or more sets of contacts

12. What are two problems that can cause an air conditioning system to have an excessively high superheat...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An open internal overload protector
It would cause the low-side pressure to decrease
An uninsulated suction line and a restricted metering device

13. Why is it unsafe to operate an air conditioning system with a low charge...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An uninsulated suction line and a restricted metering device
The sight glass is full of liquid+the sight glass is full of gas
Both technicians are incorrect

14. What are the operating pressures of an oil pressure safety switch...
An uninsulated suction line and a restricted metering device
The oil pump pressure and the crankcase pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
Run with high head and high suction pressure

15. 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
Technician B
Both technicians are correct
Broken rings+broken valves+seized bearings

16. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Current in the compressor circuit
Contains a solenoid coil and one or more sets of contacts
A vacuum test+oil traces around fittings+soap bubble solution
The discharge pressure increases and the amperage increases

17. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Evaporator and compressor
An increase in low-side pressure
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser

18. What are the symptoms of an air conditioning system that has a low charge...
Bad compressor valve
The low-side pressure will decrease and the evaporator coil will be partially frosted
Contains a solenoid coil and one or more sets of contacts
The sensing bulb at a lower temperature than the valve body

19. The best description of a relay would be...
Both technicians are incorrect
Contains a solenoid coil and one or more sets of contacts
An overcharged system
The oil pump pressure and the crankcase pressure

20. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B

21. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
High suction pressure and low superheat
20 to 30
An acid-core suction line drier
An undercharge and low ambient conditions

22. 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 start capacitor and a solid-state relay
Technician B
An undercharge and low ambient conditions

23. Which of the following could be the cause for a system's discharge and suction pressure being low...
An increase in suction pressure and an increase in discharge pressure
A restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure
The discharge pressure increases and the amperage increases

24. What type of problems can be caused by an oversized air conditioning system...
Technician B
A bad thermostat
Short cycling and insufficient dehumidification
Low voltage and a faulty start relay

25. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An increase of air leakage from ductwork

26. 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
High superheat and low discharge pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A start relay

27. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
50-65
Whenever necessary
An acid-core suction line drier
An overcharged system

28. 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 restricted metering device
Broken rings+broken valves+seized bearings
A blown fuse
An increase in suction pressure and an increase in discharge pressure

29. Insufficient airflow can be caused by...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Current in the compressor circuit
A sensing bulb improperly connected to the suction line
An increase of air leakage from ductwork

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
An increase in suction pressure and an increase in discharge pressure
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
A bad thermostat

31. Which of the following is a common cause of an excessively low superheat on a TXV system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
It is used to control refrigerant pressure in the compressor crankcase
A sensing bulb improperly connected to the suction line
An open internal overload protector

32. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A start capacitor and a solid-state relay
Partially frosted evaporator and high superheat
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan

33. Which of the following could be the cause for a system's discharge and suction pressure being low...
An increase in low-side pressure
Increases starting torque
'G' to 'C'
A restricted metering device

34. 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 incorrect
The sight glass is full of liquid+the sight glass is full of gas
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

35. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Current in the compressor circuit
High superheat and low discharge pressure
A low refrigerant charge
The discharge pressure increases and the amperage increases

36. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Whenever necessary
3 psig
Always have some liquid present in the bulb and diaphragm
Technician B

37. What type of problems can be caused by an oversized air conditioning system...
A vacuum test+oil traces around fittings+soap bubble solution
Short cycling and insufficient dehumidification
Bad compressor valve
Rise more than normal

38. What are the operating pressures of an oil pressure safety switch...
It is used to control refrigerant pressure in the compressor crankcase
The oil pump pressure and the crankcase pressure
Technician B
It keeps a constant superheat in the evaporator

39. 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...
Broken rings+broken valves+seized bearings
Low voltage and a faulty start relay
An increase in suction pressure and an increase in discharge pressure
A missing air filter+improper rotation of the indoor blower+blower too small

40. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Always have some liquid present in the bulb and diaphragm
A start relay
Both technicians are incorrect
110-120

41. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
3 psig
A vacuum test+oil traces around fittings+soap bubble solution
Low voltage and a faulty start relay
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

42. Which of the following can cause low superheat in a TXV system...
A missing air filter+improper rotation of the indoor blower+blower too small
A bad thermostat
An uninsulated TXV sensing bulb
The superheat will increase and the low-side pressure will decrease

43. 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
An overcharged system
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

44. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Low discharge pressure - high suction pressure - and low amp draw
Increases starting torque
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

45. 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 plugged filter drier
Technician A
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

46. A commercial customer calls on a 90
It keeps a constant superheat in the evaporator
The system has been overcharged+The system has air trapped in the condenser
110-120
An uninsulated TXV sensing bulb

47. Air filters should be replaced...
Whenever necessary
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Low discharge pressure - high suction pressure - and low amp draw
Technician A

48. 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
Clean the condenser coil
It would cause the low-side pressure to decrease
A vacuum test+oil traces around fittings+soap bubble solution

49. Air filters should be replaced...
Condenser fans operating during a low ambient condition and a low suction pressure
Technician A is correct
Whenever necessary
A vacuum test+oil traces around fittings+soap bubble solution

50. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Technician B
A sensing bulb improperly connected to the suction line
It would cause the low-side pressure to decrease
The internal overload is opened