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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 common methods that are used for leak-testing a system...
A start capacitor and a solid-state relay
A start relay
Technician B
A vacuum test+oil traces around fittings+soap bubble solution

2. A customer calls with an insufficient cooling complaint on a 90
Both technicians are incorrect
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An undercharged system+insufficient airflow over the evaporator coil

3. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Whenever necessary
An open internal overload protector
A restricted metering device
A dirty condenser - recirculation of condenser air - and a defective condenser fan

4. Superheat is found in an air conditioning system in the...
Lack of airflow
Evaporator and compressor
An open internal overload protector
The sight glass is full of liquid+the sight glass is full of gas

5. 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
110-120
Whenever necessary
A sensing bulb improperly connected to the suction line

6. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
The external equalizer could be plugged
The sensing bulb at a lower temperature than the valve body
Flooding the condenser - cycling condenser fans - and dampering condenser air
It would cause the low-side pressure to decrease

7. 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...
Technician B
The internal overload is opened
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

8. A hard-start kit consists of...
An overcharged system
Technician A is correct
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A start capacitor and a solid-state relay

9. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It is used to control refrigerant pressure in the compressor crankcase
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

10. When using a vapor-charged TXV bulb - it is necessary to have...
A missing air filter+improper rotation of the indoor blower+blower too small
The sensing bulb at a lower temperature than the valve body
Run with high head and high suction pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

11. Which of the following will cause excessive discharge pressures on an air conditioning system...
A vacuum test+oil traces around fittings+soap bubble solution
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
It would cause the low-side pressure to decrease
Increases starting torque

12. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An increase in suction pressure and an increase in discharge pressure
High suction pressure and low superheat

13. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Technician B
Contains a solenoid coil and one or more sets of contacts
A plugged filter drier
Whenever necessary

14. The internal overload of an air conditioning compressor senses winding temperature and...
A start capacitor and a solid-state relay
Short cycling and insufficient dehumidification
The sensing bulb at a lower temperature than the valve body
Current in the compressor circuit

15. 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
An overcharged system
'G' to 'C'
A restricted metering device
It would cause the low-side pressure to decrease

16. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Evaporator and compressor
The discharge pressure increases and the amperage increases
Flooding the condenser - cycling condenser fans - and dampering condenser air

17. A commercial customer calls on a 90
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An increase in suction pressure and an increase in discharge pressure
Whenever necessary
The system has been overcharged+The system has air trapped in the condenser

18. When using a vapor-charged TXV bulb - it is necessary to have...
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
The sensing bulb at a lower temperature than the valve body
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

19. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
110-120
Partially frosted evaporator and high superheat
It keeps a constant superheat in the evaporator

20. What problem can cause an increase of discharge pressure and an increase of suction pressure...
110-120
Broken rings+broken valves+seized bearings
A plugged filter drier
An overcharged system

21. Which of the following is a possible cause for a compressor to overheat...
A sensing bulb improperly connected to the suction line
Both technicians are correct
A start capacitor and a solid-state relay
A low refrigerant charge

22. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
('Y' and 'C') and ('G' and 'C')
Low voltage and a faulty start relay
An overcharged system
An increase in suction pressure and an increase in discharge pressure

23. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
The discharge pressure increases and the amperage increases
The oil pump pressure and the crankcase pressure
Run with high head and high suction pressure

24. 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 restricted metering device
An acid-core suction line drier
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

25. What is the purpose of a CPR valve...
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
Technician B
It is used to control refrigerant pressure in the compressor crankcase

26. A hard-start kit for an air conditioning system...
Increases starting torque
Low discharge pressure - high suction pressure - and low amp draw
Lack of airflow
An undercharged system+insufficient airflow over the evaporator coil

27. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
Clean the condenser coil
A vacuum test+oil traces around fittings+soap bubble solution
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

28. Superheat is found in an air conditioning system in the...
Condenser fans operating during a low ambient condition and a low suction pressure
Evaporator and compressor
High superheat and low discharge pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

29. 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
3 psig
The discharge pressure increases and the amperage increases
('Y' and 'C') and ('G' and 'C')
Both technicians are incorrect

30. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The discharge pressure increases and the amperage increases
An uninsulated TXV sensing bulb

31. 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
Low superheat
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Bad compressor valve

32. Which of the following will cause excessive discharge pressures on an air conditioning system...
It keeps a constant superheat in the evaporator
A plugged filter drier
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

33. 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...
The superheat will increase and the low-side pressure will decrease
Condenser fans operating during a low ambient condition and a low suction pressure
Short cycling and insufficient dehumidification
High suction pressure and low superheat

34. A customer calls with an insufficient cooling complaint on a 90
Rise more than normal
Technician B
Increases starting torque
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

35. Which of the following is a possible cause for a compressor to overheat...
An uninsulated TXV sensing bulb
A plugged filter drier
Technician A is correct
A low refrigerant charge

36. What is the purpose of the TXV...
A low refrigerant charge
A sensing bulb improperly connected to the suction line
It keeps a constant superheat in the evaporator
High superheat and low discharge pressure

37. A restricted air filter in an air conditioning system can be identified by...
Low superheat
It would cause the low-side pressure to decrease
The low-side pressure will decrease and the evaporator coil will be partially frosted
Low discharge pressure - high suction pressure - and low amp draw

38. 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
A restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Clean the condenser coil

39. 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 bad thermostat
Rise more than normal
Bad compressor valve
It would cause the low-side pressure to decrease

40. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An overcharged system
A start capacitor and a solid-state relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An uninsulated suction line and a restricted metering device

41. 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
'G' to 'C'
110-120
A plugged filter drier
Broken rings+broken valves+seized bearings

42. A compressor having tight bearings would cause the current value to...
Rise more than normal
The oil pump pressure and the crankcase pressure
Bad compressor valve
The internal overload is opened

43. A system that uses a thermal electric expansion valve...
Technician B
A start capacitor and a solid-state relay
The external equalizer could be plugged
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

44. What component is most often the cause of a start capacitor failure...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A start relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

45. 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
Always have some liquid present in the bulb and diaphragm
An undercharge and low ambient conditions
A start capacitor and a solid-state relay
The external equalizer could be plugged

46. 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 dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A restricted metering device
An uninsulated TXV sensing bulb

47. Which of the following is a common cause of an excessively low superheat on a TXV system...
An undercharge and low ambient conditions
An open internal overload protector
A sensing bulb improperly connected to the suction line
('Y' and 'C') and ('G' and 'C')

48. A compressor having tight bearings would cause the current value to...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B
Rise more than normal
('Y' and 'C') and ('G' and 'C')

49. A party-store owner tried to adjust the water valve on his water-cooled condensing unit - then he called for assistance from an HVAC/are service technician. It was found that when servicing the unit - the outlet water temperature was too low. Technic
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Run with high head and high suction pressure
20 to 30
Technician B

50. What are two common symptoms of refrigerant leaks in an air conditioning system...
Always have some liquid present in the bulb and diaphragm
Partially frosted evaporator and high superheat
Broken rings+broken valves+seized bearings
20 to 30

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NATE Air Conditioning Troubleshooting

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