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. Superheat is found in an air conditioning system in the...
High suction pressure and low superheat
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Low voltage and a faulty start relay
Evaporator and compressor

2. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
50-65
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase of air leakage from ductwork

3. Which of the following will cause excessive discharge pressures on an air conditioning system...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B
A start relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

4. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
Short cycling and insufficient dehumidification
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

5. 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
The system has been overcharged+The system has air trapped in the condenser
Both technicians are incorrect
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

6. Why is it unsafe to operate an air conditioning system with a low charge...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A defective circuit breaker
Evaporator and compressor
A defective circuit breaker

7. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Short cycling and insufficient dehumidification
Lack of airflow
A start relay

8. 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
High superheat and low discharge pressure
The sensing bulb at a lower temperature than the valve body
Bad compressor valve
Both technicians are incorrect

9. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The oil pump pressure and the crankcase pressure
Broken rings+broken valves+seized bearings
Bad compressor valve
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

10. 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
Increases starting torque
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The external equalizer could be plugged
110-120

11. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
Lack of airflow
An uninsulated suction line and a restricted metering device
The discharge pressure increases and the amperage increases
Technician B

12. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Low discharge pressure - high suction pressure - and low amp draw
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The system has been overcharged+The system has air trapped in the condenser
Partially frosted evaporator and high superheat

13. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
3 psig
Low discharge pressure - high suction pressure - and low amp draw
Both technicians are correct
A missing air filter+improper rotation of the indoor blower+blower too small

14. 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 low-side pressure will decrease and the evaporator coil will be partially frosted
High superheat and low discharge pressure
Both technicians are correct
Flooding the condenser - cycling condenser fans - and dampering condenser air

15. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
High superheat and low discharge pressure
Bad compressor valve
Increases starting torque

16. 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...
Both technicians are incorrect
Increases starting torque
Broken rings+broken valves+seized bearings
Low voltage and a faulty start relay

17. 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
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A blown fuse

18. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
110-120
The external equalizer could be plugged
Broken rings+broken valves+seized bearings
An increase in suction pressure and an increase in discharge pressure

19. Air filters should be replaced...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An uninsulated TXV sensing bulb
Whenever necessary

20. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
Run with high head and high suction pressure
Condenser fans operating during a low ambient condition and a low suction pressure
An overcharged system

21. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
An overcharged system
A start capacitor and a solid-state relay
Evaporator and compressor

22. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
Technician B
An undercharge and low ambient conditions
Both technicians are correct

23. 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
Rise more than normal
Partially frosted evaporator and high superheat
Technician B

24. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A sensing bulb improperly connected to the suction line
The superheat increases and the subcooling decreases
A low refrigerant charge
Technician B

25. 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
The system has been overcharged+The system has air trapped in the condenser
Clean the condenser coil
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B

26. 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
Lack of airflow
The discharge pressure increases and the amperage increases
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

27. What problem or problems can cause low discharge and suction pressure...
A sensing bulb improperly connected to the suction line
An undercharged system+insufficient airflow over the evaporator coil
A sensing bulb improperly connected to the suction line
A missing air filter+improper rotation of the indoor blower+blower too small

28. 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
Technician B
Technician A
3 psig
Rise more than normal

29. 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
Clean the condenser coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
An acid-core suction line drier

30. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Always have some liquid present in the bulb and diaphragm
It would cause the low-side pressure to decrease

31. What problem or problems can cause low discharge and suction pressure...
Whenever necessary
An undercharged system+insufficient airflow over the evaporator coil
A start relay
Partially frosted evaporator and high superheat

32. Which of the following can cause excessive subcooling...
Bad compressor valve
An increase in low-side pressure
A defective circuit breaker
An overcharged system

33. A system that is operating with a clear sight glass shows...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The sight glass is full of liquid+the sight glass is full of gas
An undercharge and low ambient conditions
Current in the compressor circuit

34. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
An open internal overload protector
Technician B
Technician A is correct

35. Which of the following can cause excessive subcooling...
A missing air filter+improper rotation of the indoor blower+blower too small
An overcharged system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An uninsulated suction line and a restricted metering device

36. A customer calls with an insufficient cooling complaint on a 90
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The oil pump pressure and the crankcase pressure
Technician B
An overcharged system

37. 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 discharge pressure increases and the amperage increases
Both technicians are incorrect
An undercharged system+insufficient airflow over the evaporator coil
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

38. 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
Technician A is correct
A missing air filter+improper rotation of the indoor blower+blower too small
Both technicians are correct

39. What are the symptoms of an air conditioning system that has a low charge...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Clean the condenser coil
The low-side pressure will decrease and the evaporator coil will be partially frosted

40. A hard-start kit consists of...
High suction pressure and low superheat
An acid-core suction line drier
A start capacitor and a solid-state relay
The discharge pressure increases and the amperage increases

41. 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...
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
An overcharged system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

42. What is the purpose of a CPR valve...
The system has been overcharged+The system has air trapped in the condenser
A plugged filter drier
It is used to control refrigerant pressure in the compressor crankcase
'G' to 'C'

43. What is the purpose of an EPR valve...
High superheat and low discharge pressure
A start relay
The superheat increases and the subcooling decreases
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

44. 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
An increase in low-side pressure
High superheat and low discharge pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are correct

45. What are two common symptoms of refrigerant leaks in an air conditioning system...
A plugged filter drier
The oil pump pressure and the crankcase pressure
Partially frosted evaporator and high superheat
The superheat will increase and the low-side pressure will decrease

46. A hard-start kit consists of...
It is used to control refrigerant pressure in the compressor crankcase
Bad compressor valve
A start capacitor and a solid-state relay
The oil pump pressure and the crankcase pressure

47. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Whenever necessary
20 to 30
50-65
Both technicians are incorrect

48. A liquid-charged TXV bulb will...
The superheat will increase and the low-side pressure will decrease
Always have some liquid present in the bulb and diaphragm
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

49. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
Both technicians are correct
20 to 30
A low refrigerant charge

50. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
A start capacitor and a solid-state relay
An undercharge and low ambient conditions
The discharge pressure increases and the amperage increases
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system