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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. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Both technicians are incorrect
50-65
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Flooding the condenser - cycling condenser fans - and dampering condenser air

2. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Partially frosted evaporator and high superheat
It would cause the low-side pressure to decrease
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

3. A system that is operating with a clear sight glass shows...
An increase in suction pressure and an increase in discharge pressure
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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

4. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
20 to 30
The sensing bulb at a lower temperature than the valve body
Flooding the condenser - cycling condenser fans - and dampering condenser air

5. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
3 psig
Low discharge pressure - high suction pressure - and low amp draw
Broken rings+broken valves+seized bearings
An increase in suction pressure and an increase in discharge pressure

6. When using a vapor-charged TXV bulb - it is necessary to have...
A bad thermostat
It would cause the low-side pressure to decrease
The sensing bulb at a lower temperature than the valve body
A low refrigerant charge

7. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An undercharged system+insufficient airflow over the evaporator coil
Both technicians are incorrect

8. What are two common symptoms of refrigerant leaks in an air conditioning system...
Bad compressor valve
Partially frosted evaporator and high superheat
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

9. What problem or problems can cause low discharge and suction pressure...
Short cycling and insufficient dehumidification
An undercharged system+insufficient airflow over the evaporator coil
An increase in low-side pressure
The external equalizer could be plugged

10. 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...
An uninsulated suction line and a restricted metering device
A blown fuse
High superheat and low discharge pressure
Technician B

11. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Bad compressor valve
An increase of air leakage from ductwork
High superheat and low discharge pressure

12. A commercial customer calls on a 90
Current in the compressor circuit
Both technicians are incorrect
Technician B
The system has been overcharged+The system has air trapped in the condenser

13. What are common methods that are used for leak-testing a system...
A restricted metering device
A defective circuit breaker
Lack of airflow
A vacuum test+oil traces around fittings+soap bubble solution

14. 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 oil pump pressure and the crankcase pressure
20 to 30
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A bad thermostat

15. What are the operating pressures of an oil pressure safety switch...
The discharge pressure increases and the amperage increases
The oil pump pressure and the crankcase pressure
A restricted metering device
The discharge pressure increases and the amperage increases

16. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
110-120
Technician B
Rise more than normal
An undercharge and low ambient conditions

17. 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
A sensing bulb improperly connected to the suction line
The superheat increases and the subcooling decreases
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

18. What are the symptoms of a TXV air conditioning system if it has lost its charge...
A missing air filter+improper rotation of the indoor blower+blower too small
Broken rings+broken valves+seized bearings
A vacuum test+oil traces around fittings+soap bubble solution
The superheat will increase and the low-side pressure will decrease

19. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Low superheat
The discharge pressure increases and the amperage increases
Technician B
Run with high head and high suction pressure

20. What is the common cause of a compressor burnout...
The internal overload is opened
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

21. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A plugged filter drier

22. A commercial customer calls on a 90
Current in the compressor circuit
An uninsulated suction line and a restricted metering device
The system has been overcharged+The system has air trapped in the condenser
Increases starting torque

23. 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
The sensing bulb at a lower temperature than the valve body
Broken rings+broken valves+seized bearings
Partially frosted evaporator and high superheat
A restricted metering device

24. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Technician B
An uninsulated suction line and a restricted metering device
A start relay
A plugged filter drier

25. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure
High suction pressure and low superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

26. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A bad thermostat
Flooding the condenser - cycling condenser fans - and dampering condenser air
The external equalizer could be plugged

27. 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
'G' to 'C'
Technician B
An undercharge and low ambient conditions
An overcharged system

28. What component is most often the cause of a start capacitor failure...
A start relay
Technician B
The system has been overcharged+The system has air trapped in the condenser
An uninsulated TXV sensing bulb

29. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Clean the condenser coil
Condenser fans operating during a low ambient condition and a low suction pressure
110-120
An acid-core suction line drier

30. Which of the following can cause excessive subcooling...
An overcharged system
A restricted metering device
The internal overload is opened
Short cycling and insufficient dehumidification

31. What are two common symptoms of a rooftop air conditioning system that operates with a reverse-acting high-pressure control stuck in the closed position...
Short cycling and insufficient dehumidification
An open internal overload protector
Technician A
Condenser fans operating during a low ambient condition and a low suction pressure

32. 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 low-side pressure
Current in the compressor circuit
'G' to 'C'
A bad thermostat

33. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
A bad thermostat
A low refrigerant charge
Condenser fans operating during a low ambient condition and a low suction pressure
3 psig

34. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Run with high head and high suction pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
('Y' and 'C') and ('G' and 'C')
50-65

35. A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that the outdoor condensing unit is operating - but the indoor blower is not in operation. Technician A says that it is possible that it is a bad fu
An uninsulated TXV sensing bulb
Lack of airflow
An overcharged system
Both technicians are incorrect

36. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The system has been overcharged+The system has air trapped in the condenser
Technician B

37. What is the purpose of the TXV...
50-65
The sight glass is full of liquid+the sight glass is full of gas
An acid-core suction line drier
It keeps a constant superheat in the evaporator

38. A restricted air filter in an air conditioning system can be identified by...
Bad compressor valve
Low superheat
The superheat increases and the subcooling decreases
Technician B

39. A compressor having tight bearings would cause the current value to...
Both technicians are incorrect
An uninsulated TXV sensing bulb
Technician B
Rise more than normal

40. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
A low refrigerant charge
Condenser fans operating during a low ambient condition and a low suction pressure
A restricted metering device

41. 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
A defective circuit breaker
An open internal overload protector
Current in the compressor circuit

42. Which of the following can cause excessive subcooling...
An overcharged system
The superheat will increase and the low-side pressure will decrease
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

43. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Always have some liquid present in the bulb and diaphragm
A start capacitor and a solid-state relay
Bad compressor valve
Lack of airflow

44. Why is it unsafe to operate an air conditioning system with a low charge...
A low refrigerant charge
An undercharge and low ambient conditions
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An acid-core suction line drier

45. Air filters should be replaced...
Whenever necessary
A low refrigerant charge
Low superheat
Low voltage and a faulty start relay

46. What is the common cause of a compressor burnout...
The superheat will increase and the low-side pressure will decrease
It is used to control refrigerant pressure in the compressor crankcase
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A bad thermostat

47. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...

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48. A customer who owns a split air conditioning system complains that his system has been running but his house doesn't seem to be cooling properly. When the service technician arrives on the job - he or she finds that the indoor blower is operating and
Clean the condenser coil
Technician B
The external equalizer could be plugged
An increase in suction pressure and an increase in discharge pressure

49. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
An increase of air leakage from ductwork

50. 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
An increase in low-side pressure
Both technicians are correct
Flooding the condenser - cycling condenser fans - and dampering condenser air
It keeps a constant superheat in the evaporator