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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 hard-start kit for an air conditioning system...
Increases starting torque
Contains a solenoid coil and one or more sets of contacts
It would cause the low-side pressure to decrease
Evaporator and compressor

2. A compressor having tight bearings would cause the current value to...
Whenever necessary
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Rise more than normal
A sensing bulb improperly connected to the suction line

3. A liquid-charged TXV bulb will...
A start relay
Both technicians are correct
Always have some liquid present in the bulb and diaphragm
It keeps a constant superheat in the evaporator

4. What are common methods that are used for leak-testing a system...
It is used to control refrigerant pressure in the compressor crankcase
An uninsulated TXV sensing bulb
A vacuum test+oil traces around fittings+soap bubble solution
The superheat will increase and the low-side pressure will decrease

5. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Rise more than normal
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Both technicians are incorrect

6. A customer calls and complains that his air conditioning system is not operating properly. It is noticed that the compressor is not operating. A check on the run capacitor shows that there is 33 uf and the rating on the capacitor is 40 uf. Technician
A start capacitor and a solid-state relay
Evaporator and compressor
Technician B
It keeps a constant superheat in the evaporator

7. 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 external equalizer could be plugged
A missing air filter+improper rotation of the indoor blower+blower too small
50-65
Rise more than normal

8. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Low voltage and a faulty start relay
110-120

9. A system that is operating with a clear sight glass shows...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A start relay
The sight glass is full of liquid+the sight glass is full of gas
Technician A is correct

10. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
Technician B
An uninsulated TXV sensing bulb
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A low refrigerant charge

11. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A blown fuse
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

12. 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
The low-side pressure will decrease and the evaporator coil will be partially frosted
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An open internal overload protector

13. What type of problems can be caused by an oversized air conditioning system...
3 psig
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician A is correct
Short cycling and insufficient dehumidification

14. What are the symptoms of an air conditioning system that has a low charge...
Increases starting torque
The low-side pressure will decrease and the evaporator coil will be partially frosted
Both technicians are correct
Increases starting torque

15. Technician A says that to manually pump down an air conditioning system with a two-position service valve - the liquid line must be front-seated and the high- and low-side pressure will decrease to 0 psig when the pump-down is complete. Technician B
The sensing bulb at a lower temperature than the valve body
Technician A is correct
Rise more than normal
An increase in suction pressure and an increase in discharge pressure

16. Which of the following will cause excessive discharge pressures on an air conditioning system...
The superheat will increase and the low-side pressure will decrease
Low superheat
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

17. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Lack of airflow
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

18. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The sensing bulb at a lower temperature than the valve body
Flooding the condenser - cycling condenser fans - and dampering condenser air

19. 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
An uninsulated suction line and a restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
It keeps a constant superheat in the evaporator
Broken rings+broken valves+seized bearings

20. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
It would cause the low-side pressure to decrease
Technician B
A low refrigerant charge

21. 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...
It keeps a constant superheat in the evaporator
The sensing bulb at a lower temperature than the valve body
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Low voltage and a faulty start relay

22. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Both technicians are incorrect
The superheat increases and the subcooling decreases
Low discharge pressure - high suction pressure - and low amp draw
The oil pump pressure and the crankcase pressure

23. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
The system has been overcharged+The system has air trapped in the condenser
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Short cycling and insufficient dehumidification
Rise more than normal

24. A commercial customer calls on a 90
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A low refrigerant charge
The system has been overcharged+The system has air trapped in the condenser

25. What are common methods that are used for leak-testing a system...
A missing air filter+improper rotation of the indoor blower+blower too small
It is used to control refrigerant pressure in the compressor crankcase
A vacuum test+oil traces around fittings+soap bubble solution
A start relay

26. What component is most often the cause of a start capacitor failure...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A start relay
Condenser fans operating during a low ambient condition and a low suction pressure
An increase of air leakage from ductwork

27. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
It would cause the low-side pressure to decrease
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

28. 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
Increases starting torque
A start relay
Both technicians are incorrect

29. What is the common cause of a compressor burnout...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Bad compressor valve
A start capacitor and a solid-state relay
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

30. 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
Contains a solenoid coil and one or more sets of contacts
Technician B
Bad compressor valve
Both technicians are incorrect

31. 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 open internal overload protector
Both technicians are incorrect
Bad compressor valve
Dirty condenser - bent condenser fins - and air recirculating over the condenser

32. What is the common cause of a compressor burnout...
A missing air filter+improper rotation of the indoor blower+blower too small
A start relay
A low refrigerant charge
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

33. What is the purpose of the TXV...
Technician B
Evaporator and compressor
The discharge pressure increases and the amperage increases
It keeps a constant superheat in the evaporator

34. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in low-side pressure
Low discharge pressure - high suction pressure - and low amp draw

35. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An uninsulated TXV sensing bulb
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

36. 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
High suction pressure and low superheat
Partially frosted evaporator and high superheat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A bad thermostat

37. Why is it unsafe to operate an air conditioning system with a low charge...
Whenever necessary
Current in the compressor circuit
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

38. Technician A says ' When charging a system using the superheat method - adding refrigerant to the system will increase the superheat.' Technician B says 'When charging a system using the superheat method - adding refrigerant will decrease the superhe
An increase of air leakage from ductwork
Rise more than normal
Technician B
Both technicians are incorrect

39. 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...
Low superheat
Condenser fans operating during a low ambient condition and a low suction pressure
The superheat increases and the subcooling decreases
Rise more than normal

40. 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
Increases starting torque
A defective circuit breaker
Technician B
A bad thermostat

41. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Bad compressor valve
The external equalizer could be plugged

42. Which of the following is a possible cause for a compressor to overheat...
50-65
It would cause the low-side pressure to decrease
An increase of air leakage from ductwork
A low refrigerant charge

43. 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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44. What problem can cause an increase of discharge pressure and an increase of suction pressure...
The sensing bulb at a lower temperature than the valve body
Short cycling and insufficient dehumidification
The sight glass is full of liquid+the sight glass is full of gas
An overcharged system

45. What causes the automatic expansion valve to close...
The superheat increases and the subcooling decreases
An increase in low-side pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An acid-core suction line drier

46. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The sensing bulb at a lower temperature than the valve body
A defective circuit breaker
The superheat increases and the subcooling decreases
The discharge pressure increases and the amperage increases

47. 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 overcharged system
Technician B
The external equalizer could be plugged
Both technicians are incorrect

48. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
An overcharged system
Short cycling and insufficient dehumidification
A sensing bulb improperly connected to the suction line
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

49. Why is it unsafe to operate an air conditioning system with a low charge...
Technician B
A bad thermostat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Low superheat

50. Which of the following can cause excessive subcooling...
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
110-120
An overcharged system