Test your basic knowledge |

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 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
Whenever necessary
50-65
Technician B
An undercharged system+insufficient airflow over the evaporator coil

2. A hard-start kit for an air conditioning system...
The sight glass is full of liquid+the sight glass is full of gas
Current in the compressor circuit
Both technicians are incorrect
Increases starting torque

3. The internal overload of an air conditioning compressor senses winding temperature and...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A restricted metering device
Current in the compressor circuit
The sight glass is full of liquid+the sight glass is full of gas

4. 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
Contains a solenoid coil and one or more sets of contacts
Bad compressor valve
The system has been overcharged+The system has air trapped in the condenser

5. 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
Run with high head and high suction pressure
Broken rings+broken valves+seized bearings
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A bad thermostat

6. 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
An open internal overload protector
An increase in suction pressure and an increase in discharge pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Clean the condenser coil

7. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
20 to 30
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An undercharge and low ambient conditions
The low-side pressure will decrease and the evaporator coil will be partially frosted

8. What causes the automatic expansion valve to close...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An increase in low-side pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
The internal overload is opened

9. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
High suction pressure and low superheat
It would cause the low-side pressure to decrease
The internal overload is opened
The discharge pressure increases and the amperage increases

10. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
An open internal overload protector
An overcharged system
High suction pressure and low superheat
It would cause the low-side pressure to decrease

11. Which of the following is a common cause of an excessively low superheat on a TXV system...
Technician B
A restricted metering device
An overcharged system
A sensing bulb improperly connected to the suction line

12. 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
('Y' and 'C') and ('G' and 'C')
Clean the condenser coil
Technician B

13. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Low superheat
Condenser fans operating during a low ambient condition and a low suction pressure

14. Which of the following can cause low superheat in a TXV system...
Technician B
Always have some liquid present in the bulb and diaphragm
An uninsulated TXV sensing bulb
A plugged filter drier

15. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
Whenever necessary
A missing air filter+improper rotation of the indoor blower+blower too small
Rise more than normal

16. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A start relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An overcharged system
The superheat increases and the subcooling decreases

17. What is the purpose of a CPR valve...
The oil pump pressure and the crankcase pressure
It is used to control refrigerant pressure in the compressor crankcase
An undercharge and low ambient conditions
The superheat increases and the subcooling decreases

18. Superheat is found in an air conditioning system in the...
An open internal overload protector
Evaporator and compressor
The discharge pressure increases and the amperage increases
Always have some liquid present in the bulb and diaphragm

19. A system that is operating with a clear sight glass shows...
A defective circuit breaker
A blown fuse
The sight glass is full of liquid+the sight glass is full of gas
A start capacitor and a solid-state relay

20. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
It is used to control refrigerant pressure in the compressor crankcase
It keeps a constant superheat in the evaporator
50-65

21. If a rooftop air conditioning system does not have any means of low ambient protection - what will be two symptoms of the system when operating under a low ambient condition...
The external equalizer could be plugged
High superheat and low discharge pressure
The external equalizer could be plugged
An overcharged system

22. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An acid-core suction line drier
Technician A

23. A system that is operating with a clear sight glass shows...
An increase in low-side pressure
A vacuum test+oil traces around fittings+soap bubble solution
The sight glass is full of liquid+the sight glass is full of gas
Increases starting torque

24. 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
Current in the compressor circuit
The external equalizer could be plugged
Technician B
Both technicians are incorrect

25. What are the symptoms of an air conditioning system that has a low charge...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
A start capacitor and a solid-state relay
Increases starting torque

26. The temperature range of the suction line from an air conditioning system should be...
It is used to control refrigerant pressure in the compressor crankcase
50-65
The system has been overcharged+The system has air trapped in the condenser
Contains a solenoid coil and one or more sets of contacts

27. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
The discharge pressure increases and the amperage increases
Both technicians are incorrect
Short cycling and insufficient dehumidification

28. When using a vapor-charged TXV bulb - it is necessary to have...
An increase in suction pressure and an increase in discharge pressure
The superheat increases and the subcooling decreases
It keeps a constant superheat in the evaporator
The sensing bulb at a lower temperature than the valve body

29. A restricted air filter in an air conditioning system can be identified by...
A missing air filter+improper rotation of the indoor blower+blower too small
The sensing bulb at a lower temperature than the valve body
3 psig
Low superheat

30. The best description of a relay would be...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The external equalizer could be plugged
Contains a solenoid coil and one or more sets of contacts
An undercharge and low ambient conditions

31. What component is most often the cause of a start capacitor failure...
A start relay
Always have some liquid present in the bulb and diaphragm
The sight glass is full of liquid+the sight glass is full of gas
('Y' and 'C') and ('G' and 'C')

32. 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
Low superheat
Increases starting torque
Technician B
The sight glass is full of liquid+the sight glass is full of gas

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
It is used to control refrigerant pressure in the compressor crankcase
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician A is correct

34. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
An increase in low-side pressure
The system has been overcharged+The system has air trapped in the condenser
The discharge pressure increases and the amperage increases
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

35. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
High superheat and low discharge pressure
It would cause the low-side pressure to decrease
An undercharge and low ambient conditions
The external equalizer could be plugged

36. What is the purpose of the TXV...
The superheat increases and the subcooling decreases
Technician A
Whenever necessary
It keeps a constant superheat in the evaporator

37. 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...
3 psig
An open internal overload protector
An increase of air leakage from ductwork
Condenser fans operating during a low ambient condition and a low suction pressure

38. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An uninsulated suction line and a restricted metering device
An increase in suction pressure and an increase in discharge pressure

39. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A missing air filter+improper rotation of the indoor blower+blower too small
The sensing bulb at a lower temperature than the valve body
50-65
A plugged filter drier

40. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
High suction pressure and low superheat
Technician B
An increase in low-side pressure

41. 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 has been overcharged+The system has air trapped in the condenser
A defective circuit breaker
It is used to control refrigerant pressure in the compressor crankcase
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

42. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
('Y' and 'C') and ('G' and 'C')

43. 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
It keeps a constant superheat in the evaporator
Increases starting torque
Dirty condenser - bent condenser fins - and air recirculating over the condenser

44. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A plugged filter drier
A plugged filter drier
20 to 30

45. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Technician B
Partially frosted evaporator and high superheat
Low superheat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

46. A hard-start kit consists of...
Broken rings+broken valves+seized bearings
Flooding the condenser - cycling condenser fans - and dampering condenser air
The internal overload is opened
A start capacitor and a solid-state relay

47. A system that uses a thermal electric expansion valve...
High suction pressure and low superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Flooding the condenser - cycling condenser fans - and dampering condenser air
Lack of airflow

48. Insufficient airflow can be caused by...
Bad compressor valve
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An increase of air leakage from ductwork
Low voltage and a faulty start relay

49. What component is most often the cause of a start capacitor failure...
A start relay
A defective circuit breaker
Low discharge pressure - high suction pressure - and low amp draw
Dirty condenser - bent condenser fins - and air recirculating over the condenser

50. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
Technician B
An increase in suction pressure and an increase in discharge pressure
Lack of airflow