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. Air filters should be replaced...
A bad thermostat
Whenever necessary
The discharge pressure increases and the amperage increases
Both technicians are incorrect

2. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Condenser fans operating during a low ambient condition and a low suction pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Increases starting torque
An increase in low-side pressure

3. What three things can prevent an air conditioning system from releasing heat at the proper rate...
An open internal overload protector
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

4. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
An uninsulated TXV sensing bulb
Technician B
50-65

5. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The internal overload is opened
('Y' and 'C') and ('G' and 'C')

6. What are the symptoms of a TXV air conditioning system if it has lost its charge...
A vacuum test+oil traces around fittings+soap bubble solution
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The superheat will increase and the low-side pressure will decrease
The superheat increases and the subcooling decreases

7. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Run with high head and high suction pressure
3 psig
A plugged filter drier
A start relay

8. What are the operating pressures of an oil pressure safety switch...
Low superheat
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Partially frosted evaporator and high superheat
The oil pump pressure and the crankcase pressure

9. What is the common cause of a compressor burnout...
The external equalizer could be plugged
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Both technicians are incorrect

10. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Technician B
A restricted metering device
An acid-core suction line drier
A plugged filter drier

11. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An uninsulated suction line and a restricted metering device
An overcharged system
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
20 to 30

12. What causes the automatic expansion valve to close...
A blown fuse
A low refrigerant charge
It is used to control refrigerant pressure in the compressor crankcase
An increase in low-side pressure

13. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Low voltage and a faulty start relay
Bad compressor valve
Technician B
Technician B

14. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
Low discharge pressure - high suction pressure - and low amp draw

15. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
An overcharged system
An increase in suction pressure and an increase in discharge pressure
An undercharged system+insufficient airflow over the evaporator coil
High suction pressure and low superheat

16. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
The sensing bulb at a lower temperature than the valve body
It would cause the low-side pressure to decrease
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
3 psig

17. A hard-start kit consists of...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Partially frosted evaporator and high superheat
A start capacitor and a solid-state relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

18. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
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
3 psig
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

19. What component is most often the cause of a start capacitor failure...
Rise more than normal
High suction pressure and low superheat
A start relay
A start capacitor and a solid-state relay

20. Which of the following can cause excessive subcooling...
Bad compressor valve
High suction pressure and low superheat
An overcharged system
A start relay

21. A customer calls with an insufficient cooling complaint on a 90
Both technicians are correct
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician A is correct

22. 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
A start relay
Broken rings+broken valves+seized bearings
Both technicians are incorrect
An increase in low-side pressure

23. When using a vapor-charged TXV bulb - it is necessary to have...
The superheat will increase and the low-side pressure will decrease
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The sensing bulb at a lower temperature than the valve body
Current in the compressor circuit

24. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
It is used to control refrigerant pressure in the compressor crankcase
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

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
Technician B
Increases starting torque
The system has been overcharged+The system has air trapped in the condenser
It would cause the low-side pressure to decrease

26. The internal overload of an air conditioning compressor senses winding temperature and...
The superheat will increase and the low-side pressure will decrease
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Current in the compressor circuit

27. 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...
The internal overload is opened
The sight glass is full of liquid+the sight glass is full of gas
Technician B
Evaporator and compressor

28. 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
High superheat and low discharge pressure
The external equalizer could be plugged
An overcharged system
An increase in low-side pressure

29. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
High suction pressure and low superheat

30. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
'G' to 'C'
An overcharged system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

31. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
An uninsulated TXV sensing bulb
An uninsulated suction line and a restricted metering device
It keeps a constant superheat in the evaporator

32. Which of the following can cause low superheat in a TXV system...
An increase of air leakage from ductwork
An uninsulated TXV sensing bulb
The superheat will increase and the low-side pressure will decrease
It is used to control refrigerant pressure in the compressor crankcase

33. Insufficient airflow can be caused by...
A defective circuit breaker
Technician A is correct
An increase of air leakage from ductwork
20 to 30

34. What is the purpose of a CPR valve...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It is used to control refrigerant pressure in the compressor crankcase
A plugged filter drier
Technician B

35. What is the purpose of an EPR valve...
The oil pump pressure and the crankcase pressure
Broken rings+broken valves+seized bearings
A bad thermostat
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

36. 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...
Always have some liquid present in the bulb and diaphragm
The sight glass is full of liquid+the sight glass is full of gas
It would cause the low-side pressure to decrease
A blown fuse

37. 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
Broken rings+broken valves+seized bearings
('Y' and 'C') and ('G' and 'C')
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B

38. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician A
A sensing bulb improperly connected to the suction line
Dirty condenser - bent condenser fins - and air recirculating over the condenser

39. 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
The superheat increases and the subcooling decreases
Both technicians are incorrect
The oil pump pressure and the crankcase pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

40. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
High suction pressure and low superheat
Both technicians are correct
The sight glass is full of liquid+the sight glass is full of gas

41. The temperature range of the suction line from an air conditioning system should be...
50-65
An overcharged system
Always have some liquid present in the bulb and diaphragm
Contains a solenoid coil and one or more sets of contacts

42. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
High suction pressure and low superheat
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system has been overcharged+The system has air trapped in the condenser
Dirty condenser - bent condenser fins - and air recirculating over the condenser

43. What is the purpose of the TXV...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician A
It keeps a constant superheat in the evaporator
High superheat and low discharge pressure

44. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
The superheat increases and the subcooling decreases
3 psig
Condenser fans operating during a low ambient condition and a low suction pressure

45. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Technician B
Broken rings+broken valves+seized bearings
The superheat increases and the subcooling decreases
The discharge pressure increases and the amperage increases

46. What are the symptoms of an air conditioning system that has a low charge...
50-65
An increase of air leakage from ductwork
The low-side pressure will decrease and the evaporator coil will be partially frosted
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

47. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Flooding the condenser - cycling condenser fans - and dampering condenser air
The low-side pressure will decrease and the evaporator coil will be partially frosted
The superheat increases and the subcooling decreases
It keeps a constant superheat in the evaporator

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 plugged filter drier
A bad thermostat
Both technicians are correct
An increase of air leakage from ductwork

49. 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...
Technician B
A blown fuse
An uninsulated TXV sensing bulb
An acid-core suction line drier

50. 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...
A vacuum test+oil traces around fittings+soap bubble solution
High superheat and low discharge pressure
A plugged filter drier
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device