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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. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An increase of air leakage from ductwork
The discharge pressure increases and the amperage increases
Clean the condenser coil
Lack of airflow

2. 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 low-side pressure will decrease and the evaporator coil will be partially frosted
It would cause the low-side pressure to decrease
Technician A is correct
Technician A

3. Which of the following will cause excessive discharge pressures on an air conditioning system...
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Evaporator and compressor
A start capacitor and a solid-state relay

4. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Always have some liquid present in the bulb and diaphragm
20 to 30
A missing air filter+improper rotation of the indoor blower+blower too small
50-65

5. 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
Technician A
It is used to control refrigerant pressure in the compressor crankcase
A defective circuit breaker

6. 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...

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7. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
An acid-core suction line drier
An overcharged system
Clean the condenser coil

8. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Increases starting torque
20 to 30

9. 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 oil pump pressure and the crankcase pressure
Partially frosted evaporator and high superheat
A blown fuse

10. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A defective circuit breaker
It is used to control refrigerant pressure in the compressor crankcase
An increase in suction pressure and an increase in discharge pressure

11. A restricted air filter in an air conditioning system can be identified by...
An undercharge and low ambient conditions
The external equalizer could be plugged
An uninsulated suction line and a restricted metering device
Low superheat

12. A compressor having tight bearings would cause the current value to...
High superheat and low discharge pressure
Rise more than normal
A start relay
Contains a solenoid coil and one or more sets of contacts

13. 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
('Y' and 'C') and ('G' and 'C')
The internal overload is opened
An open internal overload protector
Increases starting torque

14. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
Technician B
20 to 30
A sensing bulb improperly connected to the suction line

15. 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
The system has been overcharged+The system has air trapped in the condenser
Condenser fans operating during a low ambient condition and a low suction pressure
High superheat and low discharge pressure
Broken rings+broken valves+seized bearings

16. 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
A start relay
Always have some liquid present in the bulb and diaphragm
An open internal overload protector

17. When using a vapor-charged TXV bulb - it is necessary to have...
The internal overload is opened
The sensing bulb at a lower temperature than the valve body
Condenser fans operating during a low ambient condition and a low suction pressure
It keeps a constant superheat in the evaporator

18. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It would cause the low-side pressure to decrease
Technician A is correct
Partially frosted evaporator and high superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted

19. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A vacuum test+oil traces around fittings+soap bubble solution
110-120
The low-side pressure will decrease and the evaporator coil will be partially frosted
High suction pressure and low superheat

20. A system that is operating with a clear sight glass shows...
Bad compressor valve
Always have some liquid present in the bulb and diaphragm
The sight glass is full of liquid+the sight glass is full of gas
An undercharged system+insufficient airflow over the evaporator coil

21. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
An overcharged system
Flooding the condenser - cycling condenser fans - and dampering condenser air
Bad compressor valve
An increase of air leakage from ductwork

22. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
An undercharged system+insufficient airflow over the evaporator coil
Always have some liquid present in the bulb and diaphragm
It would cause the low-side pressure to decrease

23. When using a vapor-charged TXV bulb - it is necessary to have...
A start capacitor and a solid-state relay
Lack of airflow
The sensing bulb at a lower temperature than the valve body
The low-side pressure will decrease and the evaporator coil will be partially frosted

24. 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
Technician B
It keeps a constant superheat in the evaporator
Bad compressor valve
The sight glass is full of liquid+the sight glass is full of gas

25. A hard-start kit for an air conditioning system...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Flooding the condenser - cycling condenser fans - and dampering condenser air
Increases starting torque
Run with high head and high suction pressure

26. 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 open internal overload protector
Flooding the condenser - cycling condenser fans - and dampering condenser air
An acid-core suction line drier
A dirty condenser - recirculation of condenser air - and a defective condenser fan

27. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Broken rings+broken valves+seized bearings
Technician B
A start capacitor and a solid-state relay

28. 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...

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29. What are common methods that are used for leak-testing a system...
An acid-core suction line drier
A vacuum test+oil traces around fittings+soap bubble solution
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

30. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Increases starting torque
A plugged filter drier
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

31. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Evaporator and compressor
Technician B
An overcharged system
An increase in suction pressure and an increase in discharge pressure

32. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
50-65
Condenser fans operating during a low ambient condition and a low suction pressure
Whenever necessary

33. 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
Technician A is correct
Rise more than normal
The superheat increases and the subcooling decreases
The low-side pressure will decrease and the evaporator coil will be partially frosted

34. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
The system has been overcharged+The system has air trapped in the condenser
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The oil pump pressure and the crankcase pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser

35. 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...
110-120
A blown fuse
Contains a solenoid coil and one or more sets of contacts
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

36. 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 low-side pressure will decrease and the evaporator coil will be partially frosted
Both technicians are incorrect
Technician A
A dirty condenser - recirculation of condenser air - and a defective condenser fan

37. A hard-start kit for an air conditioning system...
3 psig
The external equalizer could be plugged
50-65
Increases starting torque

38. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
110-120
The sight glass is full of liquid+the sight glass is full of gas
A start relay

39. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
Technician A is correct
The external equalizer could be plugged
Increases starting torque

40. 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
Rise more than normal
Bad compressor valve
Clean the condenser coil

41. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
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

42. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
50-65
Lack of airflow
The superheat will increase and the low-side pressure will decrease

43. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
20 to 30
Both technicians are correct
Low voltage and a faulty start relay

44. The best description of a relay would be...
A plugged filter drier
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Current in the compressor circuit
Contains a solenoid coil and one or more sets of contacts

45. What are common methods that are used for leak-testing a system...
Clean the condenser coil
A vacuum test+oil traces around fittings+soap bubble solution
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The superheat increases and the subcooling decreases

46. The internal overload of an air conditioning compressor senses winding temperature and...
Short cycling and insufficient dehumidification
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Current in the compressor circuit
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

47. What problem can cause an increase of discharge pressure and an increase of suction pressure...
The discharge pressure increases and the amperage increases
20 to 30
An overcharged system
3 psig

48. 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 blown fuse
A vacuum test+oil traces around fittings+soap bubble solution
A bad thermostat
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

49. What is the purpose of the TXV...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The internal overload is opened
It keeps a constant superheat in the evaporator
The superheat will increase and the low-side pressure will decrease

50. 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
The external equalizer could be plugged
The external equalizer could be plugged
Technician B
Always have some liquid present in the bulb and diaphragm