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. Insufficient airflow can be caused by...
Low voltage and a faulty start relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The discharge pressure increases and the amperage increases
An increase of air leakage from ductwork

2. 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
It is used to control refrigerant pressure in the compressor crankcase
The superheat increases and the subcooling decreases
An undercharged system+insufficient airflow over the evaporator coil

3. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A restricted metering device
An uninsulated suction line and a restricted metering device
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A dirty condenser - recirculation of condenser air - and a defective condenser fan

4. The best description of a relay would be...
High suction pressure and low superheat
Technician B
A defective circuit breaker
Contains a solenoid coil and one or more sets of contacts

5. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
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')
20 to 30
A restricted metering device

6. 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
It keeps a constant superheat in the evaporator
The sight glass is full of liquid+the sight glass is full of gas
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B

7. A liquid-charged TXV bulb will...
Both technicians are correct
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An open internal overload protector
Always have some liquid present in the bulb and diaphragm

8. 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
Evaporator and compressor
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A sensing bulb improperly connected to the suction line
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

9. Which of the following is a common cause of an excessively low superheat on a TXV system...
'G' to 'C'
It is used to control refrigerant pressure in the compressor crankcase
Short cycling and insufficient dehumidification
A sensing bulb improperly connected to the suction line

10. What is the purpose of an EPR valve...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Lack of airflow
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A missing air filter+improper rotation of the indoor blower+blower too small

11. What causes the automatic expansion valve to close...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A sensing bulb improperly connected to the suction line
An increase in low-side pressure
3 psig

12. What causes the automatic expansion valve to close...
A start relay
An increase in low-side pressure
A start capacitor and a solid-state relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

13. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Technician B
Clean the condenser coil
A missing air filter+improper rotation of the indoor blower+blower too small
The low-side pressure will decrease and the evaporator coil will be partially frosted

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...
High superheat and low discharge pressure
110-120
Rise more than normal
An increase in low-side pressure

15. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Increases starting torque
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An acid-core suction line drier
The internal overload is opened

16. What type of problems can be caused by an oversized air conditioning system...
The discharge pressure increases and the amperage increases
An uninsulated suction line and a restricted metering device
Short cycling and insufficient dehumidification
Technician B

17. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Increases starting torque
Both technicians are correct
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The superheat will increase and the low-side pressure will decrease

18. 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
50-65
An overcharged system
The system has been overcharged+The system has air trapped in the condenser
A bad thermostat

19. 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 start capacitor and a solid-state relay
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The internal overload is opened

20. What is the purpose of an EPR valve...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The sensing bulb at a lower temperature than the valve body
An overcharged system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

21. 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
Low voltage and a faulty start relay
The discharge pressure increases and the amperage increases
Run with high head and high suction pressure
A bad thermostat

22. 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
An uninsulated suction line and a restricted metering device
Both technicians are correct
An uninsulated TXV sensing bulb

23. 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
('Y' and 'C') and ('G' and 'C')
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

24. Superheat is found in an air conditioning system in the...
The sight glass is full of liquid+the sight glass is full of gas
The oil pump pressure and the crankcase pressure
An overcharged system
Evaporator and compressor

25. Which of the following could be the cause for a system's discharge and suction pressure being low...
Technician A
A restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The sight glass is full of liquid+the sight glass is full of gas

26. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Technician B
It would cause the low-side pressure to decrease
The discharge pressure increases and the amperage increases
A plugged filter drier

27. When using a vapor-charged TXV bulb - it is necessary to have...
The internal overload is opened
Both technicians are incorrect
Technician B
The sensing bulb at a lower temperature than the valve body

28. 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
Technician A is correct
Technician B
Both technicians are incorrect
An increase in suction pressure and an increase in discharge pressure

29. 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 A
The superheat will increase and the low-side pressure will decrease
Technician B
A blown fuse

30. What are the operating pressures of an oil pressure safety switch...
An acid-core suction line drier
The oil pump pressure and the crankcase pressure
An uninsulated TXV sensing bulb
It would cause the low-side pressure to decrease

31. 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...
It keeps a constant superheat in the evaporator
110-120
The internal overload is opened
Flooding the condenser - cycling condenser fans - and dampering condenser air

32. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
Low voltage and a faulty start relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

33. A commercial customer calls on a 90
An uninsulated suction line and a restricted metering device
A start relay
Technician B
The system has been overcharged+The system has air trapped in the condenser

34. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A start capacitor and a solid-state relay
High suction pressure and low superheat
Always have some liquid present in the bulb and diaphragm
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

35. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The superheat will increase and the low-side pressure will decrease
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An undercharged system+insufficient airflow over the evaporator coil
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

36. What are common methods that are used for leak-testing a system...
110-120
A vacuum test+oil traces around fittings+soap bubble solution
An undercharge and low ambient conditions
Always have some liquid present in the bulb and diaphragm

37. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
An undercharge and low ambient conditions
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A bad thermostat
20 to 30

38. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Clean the condenser coil
Technician B
A start capacitor and a solid-state relay

39. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Flooding the condenser - cycling condenser fans - and dampering condenser air

40. A system that uses a thermal electric expansion valve...
Both technicians are correct
A start capacitor and a solid-state relay
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

41. What component is most often the cause of a start capacitor failure...
High superheat and low discharge pressure
A start relay
3 psig
Low discharge pressure - high suction pressure - and low amp draw

42. Why is it unsafe to operate an air conditioning system with a low charge...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A vacuum test+oil traces around fittings+soap bubble solution
A dirty condenser - recirculation of condenser air - and a defective condenser fan
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

43. What type of problems can be caused by an oversized air conditioning system...
An increase of air leakage from ductwork
110-120
Short cycling and insufficient dehumidification
The superheat increases and the subcooling decreases

44. A customer calls with an insufficient cooling complaint on a 90
Rise more than normal
Technician B
Increases starting torque
Dirty condenser - bent condenser fins - and air recirculating over the condenser

45. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Low superheat
A missing air filter+improper rotation of the indoor blower+blower too small
Partially frosted evaporator and high superheat
Both technicians are correct

46. 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
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
It keeps a constant superheat in the evaporator
A bad thermostat

47. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
The external equalizer could be plugged
110-120
A restricted metering device

48. Insufficient airflow can be caused by...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Evaporator and compressor
Partially frosted evaporator and high superheat
An increase of air leakage from ductwork

49. 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
3 psig
An increase in low-side pressure
Both technicians are correct
An open internal overload protector

50. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The internal overload is opened
The superheat will increase and the low-side pressure will decrease
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

Test your basic knowledge |

NATE Air Conditioning Troubleshooting

Top Scores

Link to This Test

Related Subjects