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. What is the purpose of an EPR valve...
50-65
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
Lack of airflow

2. A compressor having tight bearings would cause the current value to...
It would cause the low-side pressure to decrease
Rise more than normal
A plugged filter drier
Both technicians are incorrect

3. 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
Technician A is correct
High superheat and low discharge pressure
The oil pump pressure and the crankcase pressure

4. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician A
110-120
Clean the condenser coil

5. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It keeps a constant superheat in the evaporator
An acid-core suction line drier

6. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Technician A
High superheat and low discharge pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

7. What causes the automatic expansion valve to close...
An increase in low-side pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Low voltage and a faulty start relay
A start relay

8. What is the purpose of a CPR valve...
An uninsulated TXV sensing bulb
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It is used to control refrigerant pressure in the compressor crankcase
An overcharged system

9. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The sensing bulb at a lower temperature than the valve body
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
Whenever necessary

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
Condenser fans operating during a low ambient condition and a low suction pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Lack of airflow
A defective circuit breaker

11. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

12. 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
It would cause the low-side pressure to decrease
High superheat and low discharge pressure
('Y' and 'C') and ('G' and 'C')

13. 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
Rise more than normal
A blown fuse
The external equalizer could be plugged
A bad thermostat

14. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
An acid-core suction line drier
Whenever necessary
It would cause the low-side pressure to decrease

15. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
High superheat and low discharge pressure
Run with high head and high suction pressure
The superheat increases and the subcooling decreases
A missing air filter+improper rotation of the indoor blower+blower too small

16. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
It would cause the low-side pressure to decrease
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It would cause the low-side pressure to decrease
'G' to 'C'

17. What is the purpose of an EPR valve...
High suction pressure and low superheat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An overcharged system

18. 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
Broken rings+broken valves+seized bearings
A blown fuse
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

19. A liquid-charged TXV bulb will...
An increase of air leakage from ductwork
Evaporator and compressor
Always have some liquid present in the bulb and diaphragm
Both technicians are incorrect

20. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A sensing bulb improperly connected to the suction line
A missing air filter+improper rotation of the indoor blower+blower too small
Lack of airflow
Low superheat

21. What are common methods that are used for leak-testing a system...
Broken rings+broken valves+seized bearings
The superheat will increase and the low-side pressure will decrease
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

22. What are three methods for controlling a system's high-side pressure during low ambient conditions...
The external equalizer could be plugged
50-65
It is used to control refrigerant pressure in the compressor crankcase
Flooding the condenser - cycling condenser fans - and dampering condenser air

23. Insufficient airflow can be caused by...
Rise more than normal
Technician B
An increase of air leakage from ductwork
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

24. The technician observes that the compressor is not operating. The compressor windings read 5 ohms start to run - run to common is opened - and start to common is opened. The technician concludes that...
Low discharge pressure - high suction pressure - and low amp draw
A sensing bulb improperly connected to the suction line
The internal overload is opened
A blown fuse

25. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Technician A is correct
The superheat will increase and the low-side pressure will decrease
Rise more than normal
It keeps a constant superheat in the evaporator

26. What component is most often the cause of a start capacitor failure...
A start relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

27. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Clean the condenser coil
Partially frosted evaporator and high superheat
20 to 30
Always have some liquid present in the bulb and diaphragm

28. A system that is operating with a clear sight glass shows...
Both technicians are incorrect
A start capacitor and a solid-state relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The sight glass is full of liquid+the sight glass is full of gas

29. A commercial customer calls on a 90
A restricted metering device
The system has been overcharged+The system has air trapped in the condenser
A plugged filter drier
High suction pressure and low superheat

30. 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
Low voltage and a faulty start relay
Technician B
('Y' and 'C') and ('G' and 'C')
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

31. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A bad thermostat
A blown fuse
The superheat will increase and the low-side pressure will decrease
Bad compressor valve

32. Air filters should be replaced...
Whenever necessary
A bad thermostat
3 psig
110-120

33. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Run with high head and high suction pressure
Short cycling and insufficient dehumidification
The superheat increases and the subcooling decreases
Technician B

34. What is the purpose of the TXV...
Whenever necessary
Technician A is correct
Low discharge pressure - high suction pressure - and low amp draw
It keeps a constant superheat in the evaporator

35. Which of the following is a possible cause for a compressor to overheat...
Lack of airflow
A plugged filter drier
The superheat will increase and the low-side pressure will decrease
A low refrigerant charge

36. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
It would cause the low-side pressure to decrease
An undercharged system+insufficient airflow over the evaporator coil

37. When using a vapor-charged TXV bulb - it is necessary to have...
Both technicians are incorrect
Technician B
The sensing bulb at a lower temperature than the valve body
Partially frosted evaporator and high superheat

38. Which of the following can cause excessive subcooling...
The internal overload is opened
Short cycling and insufficient dehumidification
Partially frosted evaporator and high superheat
An overcharged system

39. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It would cause the low-side pressure to decrease
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Broken rings+broken valves+seized bearings

40. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
The superheat will increase and the low-side pressure will decrease
It would cause the low-side pressure to decrease
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Rise more than normal

41. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An overcharged system
An uninsulated suction line and a restricted metering device
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The superheat increases and the subcooling decreases

42. Which of the following could be the cause for a system's discharge and suction pressure being low...
Low superheat
An increase in suction pressure and an increase in discharge pressure
A restricted metering device
The oil pump pressure and the crankcase pressure

43. 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
A defective circuit breaker
The superheat increases and the subcooling decreases
Evaporator and compressor

44. What type of problems can be caused by an oversized air conditioning system...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A bad thermostat
Short cycling and insufficient dehumidification
A defective circuit breaker

45. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
An overcharged system
The external equalizer could be plugged
A defective circuit breaker

46. A compressor having tight bearings would cause the current value to...
Broken rings+broken valves+seized bearings
Rise more than normal
Lack of airflow
The internal overload is opened

47. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
20 to 30
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
High suction pressure and low superheat
Always have some liquid present in the bulb and diaphragm

48. 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
An acid-core suction line drier
An increase in suction pressure and an increase in discharge pressure
Technician B
A low refrigerant charge

49. Insufficient airflow can be caused by...
Whenever necessary
An increase of air leakage from ductwork
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

50. 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
An increase in suction pressure and an increase in discharge pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Low discharge pressure - high suction pressure - and low amp draw