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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. 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
50-65
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A plugged filter drier

2. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
A blown fuse
3 psig
20 to 30
Low superheat

3. 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...
Whenever necessary
Technician B
110-120
A blown fuse

4. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
A plugged filter drier
The low-side pressure will decrease and the evaporator coil will be partially frosted
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Always have some liquid present in the bulb and diaphragm

5. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Evaporator and compressor
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A bad thermostat
110-120

6. What problem can cause an increase of discharge pressure and an increase of suction pressure...
High suction pressure and low superheat
50-65
Technician B
An overcharged system

7. Which of the following will cause excessive discharge pressures on an air conditioning system...
An overcharged system
Short cycling and insufficient dehumidification
The sensing bulb at a lower temperature than the valve body
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

8. 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
Run with high head and high suction pressure
Current in the compressor circuit
Technician B
Both technicians are correct

9. A system that uses a thermal electric expansion valve...
The superheat increases and the subcooling decreases
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
Current in the compressor circuit

10. Which of the following will cause excessive discharge pressures on an air conditioning system...
It keeps a constant superheat in the evaporator
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
Technician A is correct

11. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
An undercharged system+insufficient airflow over the evaporator coil
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
High suction pressure and low superheat

12. 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
Low voltage and a faulty start relay
Technician B
Current in the compressor circuit

13. The temperature range of the suction line from an air conditioning system should be...
Whenever necessary
50-65
'G' to 'C'
Whenever necessary

14. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Low discharge pressure - high suction pressure - and low amp draw
The discharge pressure increases and the amperage increases
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A missing air filter+improper rotation of the indoor blower+blower too small

15. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
An overcharged system
20 to 30
Partially frosted evaporator and high superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted

16. 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
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The internal overload is opened
A bad thermostat
Technician B

17. The temperature range of the suction line from an air conditioning system should be...
Contains a solenoid coil and one or more sets of contacts
Dirty condenser - bent condenser fins - and air recirculating over the condenser
50-65
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

18. The best description of a relay would be...
Current in the compressor circuit
An increase in suction pressure and an increase in discharge pressure
Contains a solenoid coil and one or more sets of contacts
It is used to control refrigerant pressure in the compressor crankcase

19. 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...
Evaporator and compressor
An undercharge and low ambient conditions
The internal overload is opened
Whenever necessary

20. 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
The sight glass is full of liquid+the sight glass is full of gas
A restricted metering device
The external equalizer could be plugged
Technician B

21. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Lack of airflow
An uninsulated suction line and a restricted metering device
Low discharge pressure - high suction pressure - and low amp draw
'G' to 'C'

22. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
The sight glass is full of liquid+the sight glass is full of gas
A start capacitor and a solid-state relay
Bad compressor valve
3 psig

23. Which of the following could be the cause for a system's discharge and suction pressure being low...
Both technicians are correct
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Run with high head and high suction pressure
A restricted metering device

24. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
The internal overload is opened
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Evaporator and compressor

25. 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
Low superheat
A start relay
20 to 30

26. Superheat is found in an air conditioning system in the...
Condenser fans operating during a low ambient condition and a low suction pressure
Both technicians are incorrect
Low superheat
Evaporator and compressor

27. When using a vapor-charged TXV bulb - it is necessary to have...
Both technicians are incorrect
The sensing bulb at a lower temperature than the valve body
Technician B
Increases starting torque

28. What type of problems can be caused by an oversized air conditioning system...
Technician B
Technician B
An overcharged system
Short cycling and insufficient dehumidification

29. 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
Current in the compressor circuit
An undercharge and low ambient conditions
An open internal overload protector
A blown fuse

30. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The internal overload is opened
The superheat increases and the subcooling decreases
Technician A

31. What component is most often the cause of a start capacitor failure...
Evaporator and compressor
Both technicians are incorrect
The low-side pressure will decrease and the evaporator coil will be partially frosted
A start relay

32. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
An acid-core suction line drier
20 to 30
Evaporator and compressor
An overcharged system

33. 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
An open internal overload protector
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
The external equalizer could be plugged

34. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Partially frosted evaporator and high superheat
Low superheat
An increase in low-side pressure

35. 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
Lack of airflow
An overcharged system
A defective circuit breaker

36. 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
Both technicians are incorrect
An overcharged system
The system has been overcharged+The system has air trapped in the condenser

37. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
The superheat increases and the subcooling decreases
The oil pump pressure and the crankcase pressure
An undercharge and low ambient conditions

38. Which of the following can cause excessive subcooling...
The internal overload is opened
An overcharged system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Low voltage and a faulty start relay

39. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
Broken rings+broken valves+seized bearings
An undercharged system+insufficient airflow over the evaporator coil

40. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Rise more than normal
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A low refrigerant charge

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
The sensing bulb at a lower temperature than the valve body
Both technicians are correct
Condenser fans operating during a low ambient condition and a low suction pressure

42. The best description of a relay would be...
('Y' and 'C') and ('G' and 'C')
Contains a solenoid coil and one or more sets of contacts
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An increase in low-side pressure

43. When troubleshooting a split-system air conditioner - it is found that the compressor motor is humming but not starting. Technician A says that it could be an open internal overload protector. Technician B says that it could be a blown fuse. Which te
('Y' and 'C') and ('G' and 'C')
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Both technicians are incorrect
An increase in suction pressure and an increase in discharge pressure

44. Which of the following is a common cause of an excessively low superheat on a TXV system...
Technician B
A sensing bulb improperly connected to the suction line
An overcharged system
Current in the compressor circuit

45. 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
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
The sensing bulb at a lower temperature than the valve body
A defective circuit breaker

46. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
110-120
It keeps a constant superheat in the evaporator
It is used to control refrigerant pressure in the compressor crankcase

47. 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
Technician A is correct
Technician B
An acid-core suction line drier
Current in the compressor circuit

48. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated suction line and a restricted metering device
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Both technicians are incorrect
Run with high head and high suction pressure

49. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
High suction pressure and low superheat
Rise more than normal
3 psig

50. What is the common cause of a compressor burnout...
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The discharge pressure increases and the amperage increases
Current in the compressor circuit