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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 component is most often the cause of a start capacitor failure...
A start relay
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A vacuum test+oil traces around fittings+soap bubble solution
An increase of air leakage from ductwork

2. 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
Clean the condenser coil
Condenser fans operating during a low ambient condition and a low suction pressure
The superheat increases and the subcooling decreases
Both technicians are incorrect

3. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
An increase in suction pressure and an increase in discharge pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The system has been overcharged+The system has air trapped in the condenser
An increase in suction pressure and an increase in discharge pressure

4. 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
A blown fuse
The sight glass is full of liquid+the sight glass is full of gas
Technician B
An increase in suction pressure and an increase in discharge pressure

5. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
It is used to control refrigerant pressure in the compressor crankcase
110-120
Technician B
Partially frosted evaporator and high superheat

6. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
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
Evaporator and compressor
50-65

7. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
An increase in suction pressure and an increase in discharge pressure
A bad thermostat
Current in the compressor circuit

8. Which of the following is a possible cause for a compressor to overheat...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
A start capacitor and a solid-state relay
A low refrigerant charge

9. Which of the following can cause excessive subcooling...
An increase in suction pressure and an increase in discharge pressure
An overcharged system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Bad compressor valve

10. 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 oil pump pressure and the crankcase pressure
Bad compressor valve
An uninsulated suction line and a restricted metering device

11. 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
Evaporator and compressor
The discharge pressure increases and the amperage increases
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

12. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A bad thermostat
A start capacitor and a solid-state relay
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An uninsulated suction line and a restricted metering device

13. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
A restricted metering device
An increase of air leakage from ductwork
Technician B

14. 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
High suction pressure and low superheat
Technician A
A start capacitor and a solid-state relay
Technician B

15. 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
'G' to 'C'
Technician B
A start capacitor and a solid-state relay

16. A hard-start kit for an air conditioning system...
The oil pump pressure and the crankcase pressure
An acid-core suction line drier
Technician B
Increases starting torque

17. What are two common symptoms of refrigerant leaks in an air conditioning system...
20 to 30
Partially frosted evaporator and high superheat
Low discharge pressure - high suction pressure - and low amp draw
Both technicians are incorrect

18. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Low discharge pressure - high suction pressure - and low amp draw

19. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
An undercharged system+insufficient airflow over the evaporator coil
Technician B
Both technicians are correct

20. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A bad thermostat
High suction pressure and low superheat
An undercharged system+insufficient airflow over the evaporator coil
Low voltage and a faulty start relay

21. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
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
A blown fuse
Low discharge pressure - high suction pressure - and low amp draw

22. Which of the following can cause excessive subcooling...
An overcharged system
An increase in suction pressure and an increase in discharge pressure
A blown fuse
An open internal overload protector

23. A customer who owns a split air conditioning system complains that his system has been running but his house doesn't seem to be cooling properly. When the service technician arrives on the job - he or she finds that the indoor blower is operating and
The sensing bulb at a lower temperature than the valve body
Clean the condenser coil
A restricted metering device
Technician B

24. The internal overload of an air conditioning compressor senses winding temperature and...
The sensing bulb at a lower temperature than the valve body
A low refrigerant charge
A blown fuse
Current in the compressor circuit

25. What are the operating pressures of an oil pressure safety switch...
Low superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted
A restricted metering device
The oil pump pressure and the crankcase pressure

26. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
It is used to control refrigerant pressure in the compressor crankcase
20 to 30
Contains a solenoid coil and one or more sets of contacts
The system has been overcharged+The system has air trapped in the condenser

27. A compressor having tight bearings would cause the current value to...
Rise more than normal
Low voltage and a faulty start relay
Evaporator and compressor
110-120

28. A hard-start kit for an air conditioning system...
A plugged filter drier
Partially frosted evaporator and high superheat
Increases starting torque
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

29. Which of the following can cause low superheat in a TXV system...
The low-side pressure will decrease and the evaporator coil will be partially frosted
An uninsulated TXV sensing bulb
The internal overload is opened
Clean the condenser coil

30. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
An undercharged system+insufficient airflow over the evaporator coil
Rise more than normal
Lack of airflow
An increase of air leakage from ductwork

31. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Partially frosted evaporator and high superheat
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

32. 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 B
The superheat will increase and the low-side pressure will decrease
Both technicians are incorrect
3 psig

33. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Technician A
The superheat increases and the subcooling decreases
The sight glass is full of liquid+the sight glass is full of gas
Technician B

34. What are the symptoms of an air conditioning system that has a low charge...
An acid-core suction line drier
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
The sight glass is full of liquid+the sight glass is full of gas

35. 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
3 psig
Low voltage and a faulty start relay
Short cycling and insufficient dehumidification

36. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Whenever necessary
An open internal overload protector
A missing air filter+improper rotation of the indoor blower+blower too small
It would cause the low-side pressure to decrease

37. Why is it unsafe to operate an air conditioning system with a low charge...
A sensing bulb improperly connected to the suction line
The system has been overcharged+The system has air trapped in the condenser
Low superheat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

38. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
3 psig
A restricted metering device
An acid-core suction line drier
Technician B

39. 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
Both technicians are correct
A blown fuse
The discharge pressure increases and the amperage increases

40. What is the purpose of an EPR valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Evaporator and compressor
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

41. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...

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42. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A defective circuit breaker
Low superheat

43. What are three methods for controlling a system's high-side pressure during low ambient conditions...
An undercharge and low ambient conditions
The superheat increases and the subcooling decreases
Run with high head and high suction pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air

44. A compressor having tight bearings would cause the current value to...
20 to 30
High suction pressure and low superheat
Rise more than normal
The external equalizer could be plugged

45. Superheat is found in an air conditioning system in the...
Rise more than normal
Evaporator and compressor
Bad compressor valve
An undercharged system+insufficient airflow over the evaporator coil

46. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The system has been overcharged+The system has air trapped in the condenser
A bad thermostat
Both technicians are incorrect

47. Air filters should be replaced...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A start capacitor and a solid-state relay
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Whenever necessary

48. What is the purpose of a CPR valve...
An undercharge and low ambient conditions
It is used to control refrigerant pressure in the compressor crankcase
Technician B
Low superheat

49. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A bad thermostat
A start relay

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...
Whenever necessary
Partially frosted evaporator and high superheat
High superheat and low discharge pressure
Whenever necessary