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 common cause of a compressor burnout...
Condenser fans operating during a low ambient condition and a low suction pressure
The system has been overcharged+The system has air trapped in the condenser
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A vacuum test+oil traces around fittings+soap bubble solution

2. The temperature range of the suction line from an air conditioning system should be...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in low-side pressure
50-65

3. What component is most often the cause of a start capacitor failure...
A start relay
The external equalizer could be plugged
Broken rings+broken valves+seized bearings
A missing air filter+improper rotation of the indoor blower+blower too small

4. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A restricted metering device
Both technicians are incorrect
Technician B

5. What are two common symptoms of refrigerant leaks in an air conditioning system...
Technician B
Low voltage and a faulty start relay
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Partially frosted evaporator and high superheat

6. 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
Always have some liquid present in the bulb and diaphragm
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Clean the condenser coil

7. 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
The internal overload is opened
Run with high head and high suction pressure
A sensing bulb improperly connected to the suction line

8. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
The discharge pressure increases and the amperage increases
Bad compressor valve
High superheat and low discharge pressure
'G' to 'C'

9. A customer calls and says that her air conditioning system is not cooling properly. Upon arrival - a technician notices that the suction line and compressor have frost buildup. Technician A says that the problem is probably a low charge. Technician B
Technician B
Clean the condenser coil
A plugged filter drier
A dirty condenser - recirculation of condenser air - and a defective condenser fan

10. Which of the following can cause excessive subcooling...
Technician B
An overcharged system
A start relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

11. Which of the following will cause excessive discharge pressures on an air conditioning system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A plugged filter drier
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

12. 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
Current in the compressor circuit
A restricted metering device
An open internal overload protector
'G' to 'C'

13. What is the purpose of an EPR valve...
'G' to 'C'
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Broken rings+broken valves+seized bearings
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

14. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
The internal overload is opened
An undercharge and low ambient conditions
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The system has been overcharged+The system has air trapped in the condenser

15. 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
An increase of air leakage from ductwork
The external equalizer could be plugged
Low discharge pressure - high suction pressure - and low amp draw
The superheat increases and the subcooling decreases

16. A system that uses a thermal electric expansion valve...
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
An overcharged system

17. What are the operating pressures of an oil pressure safety switch...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The oil pump pressure and the crankcase pressure
'G' to 'C'
It keeps a constant superheat in the evaporator

18. The temperature range of the suction line from an air conditioning system should be...
50-65
Always have some liquid present in the bulb and diaphragm
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An increase in low-side pressure

19. Technician A says that to manually pump down an air conditioning system with a two-position service valve - the liquid line must be front-seated and the high- and low-side pressure will decrease to 0 psig when the pump-down is complete. Technician B
Technician A is correct
Contains a solenoid coil and one or more sets of contacts
3 psig
The internal overload is opened

20. A hard-start kit for an air conditioning system...
Low superheat
110-120
The external equalizer could be plugged
Increases starting torque

21. 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
Evaporator and compressor
The internal overload is opened
Both technicians are incorrect
The sight glass is full of liquid+the sight glass is full of gas

22. 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...
It keeps a constant superheat in the evaporator
Low voltage and a faulty start relay
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

23. A restricted air filter in an air conditioning system can be identified by...
20 to 30
Low superheat
Partially frosted evaporator and high superheat
A start capacitor and a solid-state relay

24. Which of the following is a common cause of an excessively low superheat on a TXV system...
A sensing bulb improperly connected to the suction line
Condenser fans operating during a low ambient condition and a low suction pressure
An uninsulated TXV sensing bulb
The superheat will increase and the low-side pressure will decrease

25. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Clean the condenser coil
Technician B
Technician B
A plugged filter drier

26. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

27. A compressor having tight bearings would cause the current value to...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Short cycling and insufficient dehumidification
Low voltage and a faulty start relay
Rise more than normal

28. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Evaporator and compressor
High suction pressure and low superheat
A restricted metering device
Partially frosted evaporator and high superheat

29. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
A bad thermostat
Technician B
Technician B

30. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Rise more than normal
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The oil pump pressure and the crankcase pressure
A blown fuse

31. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Flooding the condenser - cycling condenser fans - and dampering condenser air
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Broken rings+broken valves+seized bearings
High superheat and low discharge pressure

32. What causes the automatic expansion valve to close...
An increase in low-side pressure
The oil pump pressure and the crankcase pressure
An increase of air leakage from ductwork
An undercharge and low ambient conditions

33. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
Both technicians are incorrect
The superheat increases and the subcooling decreases

34. Why is it unsafe to operate an air conditioning system with a low charge...
50-65
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

35. What is the purpose of a CPR valve...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Always have some liquid present in the bulb and diaphragm
An increase of air leakage from ductwork
It is used to control refrigerant pressure in the compressor crankcase

36. 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
It would cause the low-side pressure to decrease
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The external equalizer could be plugged
Evaporator and compressor

37. A hard-start kit for an air conditioning system...
Run with high head and high suction pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A defective circuit breaker
Increases starting torque

38. What is the purpose of a CPR valve...
Flooding the condenser - cycling condenser fans - and dampering condenser air
It is used to control refrigerant pressure in the compressor crankcase
Condenser fans operating during a low ambient condition and a low suction pressure
Increases starting torque

39. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
A plugged filter drier
A bad thermostat
An open internal overload protector
3 psig

40. 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...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A blown fuse
Technician A is correct
Clean the condenser coil

41. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Run with high head and high suction pressure
Bad compressor valve
A sensing bulb improperly connected to the suction line

42. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The oil pump pressure and the crankcase pressure
20 to 30
110-120
Contains a solenoid coil and one or more sets of contacts

43. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A blown fuse
A defective circuit breaker
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Evaporator and compressor

44. 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
Run with high head and high suction pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician A
Technician B

45. Which of the following can cause excessive subcooling...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Current in the compressor circuit
A blown fuse
An overcharged system

46. 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
Always have some liquid present in the bulb and diaphragm
Both technicians are incorrect
The external equalizer could be plugged

47. What are two common symptoms of refrigerant leaks in an air conditioning system...
Low discharge pressure - high suction pressure - and low amp draw
The sight glass is full of liquid+the sight glass is full of gas
Clean the condenser coil
Partially frosted evaporator and high superheat

48. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The superheat increases and the subcooling decreases
The external equalizer could be plugged
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
110-120

49. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
Both technicians are incorrect
Bad compressor valve

50. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
High suction pressure and low superheat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device