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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 is operating with a clear sight glass shows...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
The sight glass is full of liquid+the sight glass is full of gas
20 to 30

2. 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
Clean the condenser coil
50-65
The sensing bulb at a lower temperature than the valve body

3. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High superheat and low discharge pressure
Increases starting torque
High suction pressure and low superheat
Broken rings+broken valves+seized bearings

4. Which of the following can cause low superheat in a TXV system...
Clean the condenser coil
Low voltage and a faulty start relay
Run with high head and high suction pressure
An uninsulated TXV sensing bulb

5. Which of the following could be the cause for a system's discharge and suction pressure being low...
A bad thermostat
Technician B
A restricted metering device
Low voltage and a faulty start relay

6. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A defective circuit breaker
An overcharged system

7. 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
Both technicians are incorrect
Technician B
50-65
An uninsulated suction line and a restricted metering device

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
Both technicians are correct
The external equalizer could be plugged
An undercharged system+insufficient airflow over the evaporator coil
It keeps a constant superheat in the evaporator

9. Which of the following can cause low superheat in a TXV system...
3 psig
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An uninsulated TXV sensing bulb
Dirty condenser - bent condenser fins - and air recirculating over the condenser

10. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
Evaporator and compressor
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A vacuum test+oil traces around fittings+soap bubble solution

11. A hard-start kit for an air conditioning system...
Partially frosted evaporator and high superheat
Increases starting torque
50-65
Rise more than normal

12. 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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13. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Flooding the condenser - cycling condenser fans - and dampering condenser air

14. What problem or problems can cause low discharge and suction pressure...
An undercharge and low ambient conditions
A missing air filter+improper rotation of the indoor blower+blower too small
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An undercharged system+insufficient airflow over the evaporator coil

15. What is the purpose of an EPR valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Both technicians are incorrect
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

16. Why is it unsafe to operate an air conditioning system with a low charge...
An overcharged system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The superheat increases and the subcooling decreases
An undercharge and low ambient conditions

17. A system that uses a thermal electric expansion valve...
An increase in low-side pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Both technicians are incorrect
The oil pump pressure and the crankcase pressure

18. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The internal overload is opened
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A bad thermostat

19. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Condenser fans operating during a low ambient condition and a low suction pressure

20. Which of the following is a common cause of an excessively low superheat on a TXV system...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
50-65
50-65
A sensing bulb improperly connected to the suction line

21. 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
Both technicians are incorrect
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
3 psig

22. 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
It is used to control refrigerant pressure in the compressor crankcase
It would cause the low-side pressure to decrease
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

23. Why is it unsafe to operate an air conditioning system with a low charge...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
20 to 30
Technician A
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

24. 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 A is correct
The internal overload is opened
Always have some liquid present in the bulb and diaphragm
It keeps a constant superheat in the evaporator

25. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An uninsulated suction line and a restricted metering device
('Y' and 'C') and ('G' and 'C')
Clean the condenser coil

26. The temperature range of the suction line from an air conditioning system should be...
Increases starting torque
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
50-65
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

27. 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 low refrigerant charge
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

28. What problem or problems can cause low discharge and suction pressure...
A start relay
An undercharged system+insufficient airflow over the evaporator coil
A low refrigerant charge
110-120

29. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
High suction pressure and low superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted
Lack of airflow
Technician B

30. What are the operating pressures of an oil pressure safety switch...
Increases starting torque
Technician B
The system has been overcharged+The system has air trapped in the condenser
The oil pump pressure and the crankcase pressure

31. 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
Evaporator and compressor
The sight glass is full of liquid+the sight glass is full of gas
The sensing bulb at a lower temperature than the valve body
A defective circuit breaker

32. What are two problems that can cause an air conditioning system to have an excessively high superheat...
High superheat and low discharge pressure
An undercharge and low ambient conditions
An uninsulated suction line and a restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small

33. 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
Low discharge pressure - high suction pressure - and low amp draw
The discharge pressure increases and the amperage increases
Both technicians are incorrect
Current in the compressor circuit

34. 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
The oil pump pressure and the crankcase pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
110-120
Technician B

35. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A defective circuit breaker
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
An increase in suction pressure and an increase in discharge pressure

36. 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...
A restricted metering device
Evaporator and compressor
A start relay
The internal overload is opened

37. Superheat is found in an air conditioning system in the...
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
Evaporator and compressor
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

38. What is the purpose of the TXV...
Clean the condenser coil
It keeps a constant superheat in the evaporator
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The discharge pressure increases and the amperage increases

39. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
A start capacitor and a solid-state relay
Clean the condenser coil
An increase in low-side pressure

40. When using a vapor-charged TXV bulb - it is necessary to have...
Current in the compressor circuit
Technician B
The sensing bulb at a lower temperature than the valve body
An increase in suction pressure and an increase in discharge pressure

41. 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
Both technicians are incorrect
An overcharged system
20 to 30
Technician B

42. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
110-120
The discharge pressure increases and the amperage increases
A dirty condenser - recirculation of condenser air - and a defective condenser fan
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

43. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A vacuum test+oil traces around fittings+soap bubble solution
20 to 30
Short cycling and insufficient dehumidification
Bad compressor valve

44. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
An undercharge and low ambient conditions
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are incorrect
It would cause the low-side pressure to decrease

45. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
Low discharge pressure - high suction pressure - and low amp draw
Low superheat
Clean the condenser coil

46. Insufficient airflow can be caused by...
The sight glass is full of liquid+the sight glass is full of gas
'G' to 'C'
An acid-core suction line drier
An increase of air leakage from ductwork

47. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Low discharge pressure - high suction pressure - and low amp draw
An overcharged system
Broken rings+broken valves+seized bearings
Both technicians are incorrect

48. The internal overload of an air conditioning compressor senses winding temperature and...
The external equalizer could be plugged
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Current in the compressor circuit

49. Insufficient airflow can be caused by...
Technician B
An increase of air leakage from ductwork
Rise more than normal
Condenser fans operating during a low ambient condition and a low suction pressure

50. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
('Y' and 'C') and ('G' and 'C')
Both technicians are incorrect
20 to 30
A missing air filter+improper rotation of the indoor blower+blower too small