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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 customer calls with an insufficient cooling complaint on a 90
Bad compressor valve
It is used to control refrigerant pressure in the compressor crankcase
High suction pressure and low superheat
Technician B

2. Superheat is found in an air conditioning system in the...
The external equalizer could be plugged
Short cycling and insufficient dehumidification
Evaporator and compressor
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

3. A hard-start kit for an air conditioning system...
Increases starting torque
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

4. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
An acid-core suction line drier
The superheat will increase and the low-side pressure will decrease
It would cause the low-side pressure to decrease
Clean the condenser coil

5. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A sensing bulb improperly connected to the suction line
Technician B
A plugged filter drier
A blown fuse

6. 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
Technician B
('Y' and 'C') and ('G' and 'C')
Evaporator and compressor

7. 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

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8. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A defective circuit breaker
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Both technicians are incorrect
High suction pressure and low superheat

9. A system that uses a thermal electric expansion valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
50-65
Low superheat
A plugged filter drier

10. What are the operating pressures of an oil pressure safety switch...
An uninsulated suction line and a restricted metering device
Always have some liquid present in the bulb and diaphragm
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The oil pump pressure and the crankcase pressure

11. Which of the following can cause excessive subcooling...
An overcharged system
An increase in suction pressure and an increase in discharge pressure
Technician B
A restricted metering device

12. What component is most often the cause of a start capacitor failure...
High suction pressure and low superheat
The discharge pressure increases and the amperage increases
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A start relay

13. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
A blown fuse
20 to 30
An acid-core suction line drier

14. 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 B
A low refrigerant charge
Low voltage and a faulty start relay
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

15. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Increases starting torque
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An undercharge and low ambient conditions
The sight glass is full of liquid+the sight glass is full of gas

16. What are the operating pressures of an oil pressure safety switch...
Current in the compressor circuit
Rise more than normal
An increase of air leakage from ductwork
The oil pump pressure and the crankcase pressure

17. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
50-65
3 psig

18. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A blown fuse
An uninsulated suction line and a restricted metering device
The low-side pressure will decrease and the evaporator coil will be partially frosted
Lack of airflow

19. What is the purpose of an EPR valve...
An undercharge and low ambient conditions
The oil pump pressure and the crankcase pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
It is used to control refrigerant pressure in the compressor crankcase

20. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Technician B
Run with high head and high suction pressure
An increase of air leakage from ductwork
A missing air filter+improper rotation of the indoor blower+blower too small

21. A system that uses a thermal electric expansion valve...
Clean the condenser coil
An increase of air leakage from ductwork
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
High superheat and low discharge pressure

22. Why is it unsafe to operate an air conditioning system with a low charge...
An uninsulated TXV sensing bulb
Condenser fans operating during a low ambient condition and a low suction pressure
20 to 30
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

23. 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...
It is used to control refrigerant pressure in the compressor crankcase
The external equalizer could be plugged
High superheat and low discharge pressure
Condenser fans operating during a low ambient condition and a low suction pressure

24. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
110-120
High superheat and low discharge pressure
Always have some liquid present in the bulb and diaphragm

25. When using a vapor-charged TXV bulb - it is necessary to have...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An uninsulated suction line and a restricted metering device
The sensing bulb at a lower temperature than the valve body
A blown fuse

26. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Both technicians are correct
Technician B
20 to 30
A dirty condenser - recirculation of condenser air - and a defective condenser fan

27. Air filters should be replaced...
Evaporator and compressor
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An open internal overload protector
Whenever necessary

28. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Both technicians are incorrect
It keeps a constant superheat in the evaporator
110-120
Bad compressor valve

29. 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
A blown fuse
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Both technicians are correct
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

30. 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
The sensing bulb at a lower temperature than the valve body
A sensing bulb improperly connected to the suction line
Both technicians are correct

31. What causes the automatic expansion valve to close...
It keeps a constant superheat in the evaporator
An overcharged system
An increase in low-side pressure
Technician B

32. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Technician A is correct
A bad thermostat
A missing air filter+improper rotation of the indoor blower+blower too small

33. 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
Low voltage and a faulty start relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A defective circuit breaker
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

34. What is the purpose of an EPR valve...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician A is correct
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

35. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An overcharged system
Flooding the condenser - cycling condenser fans - and dampering condenser air
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B

36. The temperature range of the suction line from an air conditioning system should be...
50-65
Technician B
An undercharge and low ambient conditions
Increases starting torque

37. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
An increase of air leakage from ductwork
The low-side pressure will decrease and the evaporator coil will be partially frosted
3 psig

38. 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
An increase in suction pressure and an increase in discharge pressure
Technician B
A plugged filter drier

39. What are the symptoms of an air conditioning system that has a low charge...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A low refrigerant charge
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted

40. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
Technician B
The superheat will increase and the low-side pressure will decrease
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

41. What type of problems can be caused by an oversized air conditioning system...
Rise more than normal
Low voltage and a faulty start relay
Condenser fans operating during a low ambient condition and a low suction pressure
Short cycling and insufficient dehumidification

42. What is the common cause of a compressor burnout...
3 psig
A vacuum test+oil traces around fittings+soap bubble solution
20 to 30
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

43. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
High superheat and low discharge pressure
20 to 30
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

44. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Increases starting torque
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
110-120

45. 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
Technician A
Low discharge pressure - high suction pressure - and low amp draw
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

46. Which of the following can cause low superheat in a TXV system...
The discharge pressure increases and the amperage increases
A sensing bulb improperly connected to the suction line
An uninsulated TXV sensing bulb
Both technicians are correct

47. Insufficient airflow can be caused by...
Contains a solenoid coil and one or more sets of contacts
A defective circuit breaker
An increase of air leakage from ductwork
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

48. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The sight glass is full of liquid+the sight glass is full of gas
A plugged filter drier
Technician B

49. Why is it unsafe to operate an air conditioning system with a low charge...
Run with high head and high suction pressure
Low superheat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

50. Which of the following will cause excessive discharge pressures on an air conditioning system...
Low discharge pressure - high suction pressure - and low amp draw
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
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