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. 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 correct
Both technicians are incorrect
Current in the compressor circuit
Low superheat

2. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Low superheat
A missing air filter+improper rotation of the indoor blower+blower too small
Current in the compressor circuit

3. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The oil pump pressure and the crankcase pressure
Low superheat
Whenever necessary

4. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Both technicians are incorrect
A sensing bulb improperly connected to the suction line
Bad compressor valve

5. 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
The internal overload is opened
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are incorrect
Clean the condenser coil

6. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
An acid-core suction line drier
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An open internal overload protector
Low discharge pressure - high suction pressure - and low amp draw

7. What are three methods for controlling a system's high-side pressure during low ambient conditions...
20 to 30
A restricted metering device
High suction pressure and low superheat
Flooding the condenser - cycling condenser fans - and dampering condenser air

8. What causes the automatic expansion valve to close...
Current in the compressor circuit
The low-side pressure will decrease and the evaporator coil will be partially frosted
Flooding the condenser - cycling condenser fans - and dampering condenser air
An increase in low-side pressure

9. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An acid-core suction line drier
An increase in low-side pressure
Lack of airflow

10. What causes the automatic expansion valve to close...
Lack of airflow
An overcharged system
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An increase in low-side pressure

11. What is the purpose of an EPR valve...
An increase of air leakage from ductwork
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An increase in suction pressure and an increase in discharge pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser

12. 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 external equalizer could be plugged
The internal overload is opened
A blown fuse
Broken rings+broken valves+seized bearings

13. 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
Lack of airflow
Clean the condenser coil
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A blown fuse

14. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Low superheat
A start relay
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Bad compressor valve

15. What component is most often the cause of a start capacitor failure...
The oil pump pressure and the crankcase pressure
A start relay
The sight glass is full of liquid+the sight glass is full of gas
High suction pressure and low superheat

16. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A bad thermostat
An uninsulated suction line and a restricted metering device
Technician B

17. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
High suction pressure and low superheat
The sensing bulb at a lower temperature than the valve body
Technician B

18. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
It keeps a constant superheat in the evaporator
Bad compressor valve
An undercharge and low ambient conditions
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

19. Superheat is found in an air conditioning system in the...
An increase in low-side pressure
Evaporator and compressor
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

20. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
A blown fuse
A plugged filter drier
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An acid-core suction line drier

21. The internal overload of an air conditioning compressor senses winding temperature and...
An increase in suction pressure and an increase in discharge pressure
Low discharge pressure - high suction pressure - and low amp draw
Current in the compressor circuit
High suction pressure and low superheat

22. A commercial customer calls on a 90
20 to 30
It keeps a constant superheat in the evaporator
The system has been overcharged+The system has air trapped in the condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted

23. What are the operating pressures of an oil pressure safety switch...
Short cycling and insufficient dehumidification
Evaporator and compressor
The oil pump pressure and the crankcase pressure
Technician B

24. A hard-start kit consists of...
3 psig
A start capacitor and a solid-state relay
An acid-core suction line drier
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

25. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A defective circuit breaker
Evaporator and compressor
Run with high head and high suction pressure

26. A system that is operating with a clear sight glass shows...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An overcharged system
The sight glass is full of liquid+the sight glass is full of gas
Current in the compressor circuit

27. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Both technicians are incorrect
A defective circuit breaker
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An uninsulated suction line and a restricted metering device

28. 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...
A low refrigerant charge
A start capacitor and a solid-state relay
Condenser fans operating during a low ambient condition and a low suction pressure
A defective circuit breaker

29. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
The discharge pressure increases and the amperage increases
Both technicians are incorrect
An acid-core suction line drier
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

30. A compressor having tight bearings would cause the current value to...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Rise more than normal
Low superheat
Bad compressor valve

31. What type of problems can be caused by an oversized air conditioning system...
Rise more than normal
Short cycling and insufficient dehumidification
An increase in low-side pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

32. What is the purpose of a CPR valve...
The superheat increases and the subcooling decreases
An uninsulated TXV sensing bulb
The system has been overcharged+The system has air trapped in the condenser
It is used to control refrigerant pressure in the compressor crankcase

33. What problem can cause an increase of discharge pressure and an increase of suction pressure...
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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An overcharged system

34. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Both technicians are correct
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A plugged filter drier
An undercharge and low ambient conditions

35. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Whenever necessary
An uninsulated TXV sensing bulb
Clean the condenser coil
A plugged filter drier

36. Superheat is found in an air conditioning system in the...
The superheat will increase and the low-side pressure will decrease
3 psig
The sight glass is full of liquid+the sight glass is full of gas
Evaporator and compressor

37. 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
Both technicians are incorrect
An increase in suction pressure and an increase in discharge pressure
Technician B
Whenever necessary

38. 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
An overcharged system
Both technicians are incorrect
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

39. Air filters should be replaced...
Technician A
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Whenever necessary
The sensing bulb at a lower temperature than the valve body

40. What is the purpose of the TXV...
An increase in low-side pressure
Technician A is correct
It keeps a constant superheat in the evaporator
An overcharged system

41. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
20 to 30
An uninsulated suction line and a restricted metering device
50-65

42. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
An undercharge and low ambient conditions
Lack of airflow
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
High superheat and low discharge pressure

43. Which of the following will cause excessive discharge pressures on an air conditioning system...
The internal overload is opened
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An increase of air leakage from ductwork

44. 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 start relay
('Y' and 'C') and ('G' and 'C')
A vacuum test+oil traces around fittings+soap bubble solution
A defective circuit breaker

45. The best description of a relay would be...
The superheat increases and the subcooling decreases
High superheat and low discharge pressure
Contains a solenoid coil and one or more sets of contacts
A dirty condenser - recirculation of condenser air - and a defective condenser fan

46. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Clean the condenser coil
Partially frosted evaporator and high superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It would cause the low-side pressure to decrease

47. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A vacuum test+oil traces around fittings+soap bubble solution
Always have some liquid present in the bulb and diaphragm
The low-side pressure will decrease and the evaporator coil will be partially frosted
It would cause the low-side pressure to decrease

48. What component is most often the cause of a start capacitor failure...
Evaporator and compressor
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A start relay
A missing air filter+improper rotation of the indoor blower+blower too small

49. The temperature range of the suction line from an air conditioning system should be...
50-65
Technician B
The system has been overcharged+The system has air trapped in the condenser
Both technicians are incorrect

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