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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 a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
50-65
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A sensing bulb improperly connected to the suction line

2. 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
An increase in suction pressure and an increase in discharge pressure
The system has been overcharged+The system has air trapped in the condenser
20 to 30

3. A hard-start kit consists of...
The oil pump pressure and the crankcase pressure
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
A start capacitor and a solid-state relay

4. 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
Evaporator and compressor
An overcharged system
A bad thermostat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

5. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Partially frosted evaporator and high superheat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A missing air filter+improper rotation of the indoor blower+blower too small
The sight glass is full of liquid+the sight glass is full of gas

6. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Whenever necessary
A blown fuse
Technician B
High suction pressure and low superheat

7. What causes the automatic expansion valve to close...
Always have some liquid present in the bulb and diaphragm
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Current in the compressor circuit
An increase in low-side pressure

8. 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
An uninsulated suction line and a restricted metering device
A low refrigerant charge
An open internal overload protector
Technician A is correct

9. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Contains a solenoid coil and one or more sets of contacts
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A vacuum test+oil traces around fittings+soap bubble solution
110-120

10. Air filters should be replaced...
Technician B
Whenever necessary
A sensing bulb improperly connected to the suction line
Run with high head and high suction pressure

11. Which of the following is a possible cause for a compressor to overheat...
A restricted metering device
A low refrigerant charge
A plugged filter drier
3 psig

12. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
It keeps a constant superheat in the evaporator
The system has been overcharged+The system has air trapped in the condenser
The superheat will increase and the low-side pressure will decrease

13. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
It would cause the low-side pressure to decrease
An undercharged system+insufficient airflow over the evaporator coil
The external equalizer could be plugged

14. 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
50-65
A restricted metering device
High suction pressure and low superheat
The external equalizer could be plugged

15. A system that is operating with a clear sight glass shows...
An open internal overload protector
It is used to control refrigerant pressure in the compressor crankcase
The sight glass is full of liquid+the sight glass is full of gas
Low superheat

16. 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 start relay
Broken rings+broken valves+seized bearings
Both technicians are correct
Flooding the condenser - cycling condenser fans - and dampering condenser air

17. What are two problems that can cause an air conditioning system to have an excessively high superheat...
High superheat and low discharge pressure
Rise more than normal
Rise more than normal
An uninsulated suction line and a restricted metering device

18. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Run with high head and high suction pressure
Lack of airflow
The oil pump pressure and the crankcase pressure
Clean the condenser coil

19. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An overcharged system
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A start capacitor and a solid-state relay

20. Superheat is found in an air conditioning system in the...
Evaporator and compressor
An undercharged system+insufficient airflow over the evaporator coil
A start relay
A vacuum test+oil traces around fittings+soap bubble solution

21. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The external equalizer could be plugged
Low discharge pressure - high suction pressure - and low amp draw
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B

22. Which of the following will cause excessive discharge pressures on an air conditioning system...
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
('Y' and 'C') and ('G' and 'C')
3 psig

23. 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
An undercharge and low ambient conditions
Whenever necessary
A vacuum test+oil traces around fittings+soap bubble solution

24. What component is most often the cause of a start capacitor failure...
Low voltage and a faulty start relay
A start relay
An undercharged system+insufficient airflow over the evaporator coil
A missing air filter+improper rotation of the indoor blower+blower too small

25. 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
A defective circuit breaker
An uninsulated TXV sensing bulb
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The internal overload is opened

26. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Technician B
Run with high head and high suction pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are incorrect

27. Air filters should be replaced...
Whenever necessary
The superheat increases and the subcooling decreases
An overcharged system
Technician B

28. What is the purpose of the TXV...
A vacuum test+oil traces around fittings+soap bubble solution
It keeps a constant superheat in the evaporator
Bad compressor valve
An increase in low-side pressure

29. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A vacuum test+oil traces around fittings+soap bubble solution
The superheat increases and the subcooling decreases
The low-side pressure will decrease and the evaporator coil will be partially frosted
An open internal overload protector

30. A technician receives an air conditioning service call stating that the system is operating but isn't cooling properly. When the technician arrives - she notices that the compressor has recently been changed and it is an are-22 system. She checks the
An overcharged system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Condenser fans operating during a low ambient condition and a low suction pressure
The superheat will increase and the low-side pressure will decrease

31. 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 sight glass is full of liquid+the sight glass is full of gas
Short cycling and insufficient dehumidification
An undercharged system+insufficient airflow over the evaporator coil
Technician B

32. 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...
A plugged filter drier
Low voltage and a faulty start relay
An increase of air leakage from ductwork
Technician A is correct

33. The best description of a relay would be...
High superheat and low discharge pressure
The superheat will increase and the low-side pressure will decrease
Contains a solenoid coil and one or more sets of contacts
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

34. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Technician B
An overcharged system
Bad compressor valve
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

35. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The superheat increases and the subcooling decreases
The system has been overcharged+The system has air trapped in the condenser
An increase in suction pressure and an increase in discharge pressure
Whenever necessary

36. 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
The sensing bulb at a lower temperature than the valve body
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

37. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The system has been overcharged+The system has air trapped in the condenser
Both technicians are correct
20 to 30
An increase in low-side pressure

38. The internal overload of an air conditioning compressor senses winding temperature and...
Evaporator and compressor
The sight glass is full of liquid+the sight glass is full of gas
Current in the compressor circuit
Both technicians are correct

39. 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
Clean the condenser coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are incorrect
50-65

40. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The superheat will increase and the low-side pressure will decrease
50-65
It is used to control refrigerant pressure in the compressor crankcase

41. Which of the following could be the cause for a system's discharge and suction pressure being low...
('Y' and 'C') and ('G' and 'C')
Technician B
A bad thermostat
A restricted metering device

42. 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
Rise more than normal
The system has been overcharged+The system has air trapped in the condenser
Clean the condenser coil
An increase in low-side pressure

43. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
('Y' and 'C') and ('G' and 'C')
Condenser fans operating during a low ambient condition and a low suction pressure
A defective circuit breaker
A plugged filter drier

44. 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

45. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician A is correct
A plugged filter drier

46. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...

47. What are the symptoms of an air conditioning system that has a low charge...
Always have some liquid present in the bulb and diaphragm
A blown fuse
An increase in suction pressure and an increase in discharge pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted

48. Which of the following can cause excessive subcooling...
An overcharged system
'G' to 'C'
Increases starting torque
An undercharged system+insufficient airflow over the evaporator coil

49. 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...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An undercharged system+insufficient airflow over the evaporator coil
A blown fuse
An acid-core suction line drier

50. 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...
The oil pump pressure and the crankcase pressure
Low voltage and a faulty start relay
A sensing bulb improperly connected to the suction line
Lack of airflow