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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. Which of the following could be the cause for a system's discharge and suction pressure being low...
An uninsulated suction line and a restricted metering device
Evaporator and compressor
A restricted metering device
A vacuum test+oil traces around fittings+soap bubble solution

2. 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
Clean the condenser coil
Always have some liquid present in the bulb and diaphragm

3. 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
Condenser fans operating during a low ambient condition and a low suction pressure
The sensing bulb at a lower temperature than the valve body
Clean the condenser coil
Technician B

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
An uninsulated TXV sensing bulb
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician A

5. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A low refrigerant charge
An undercharge and low ambient conditions
An open internal overload protector

6. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A start relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

7. Which of the following could be the cause for a system's discharge and suction pressure being low...
A sensing bulb improperly connected to the suction line
A restricted metering device
An undercharge and low ambient conditions
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

8. What causes the automatic expansion valve to close...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Lack of airflow
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An increase in low-side pressure

9. 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
An overcharged system
Technician A is correct
The sensing bulb at a lower temperature than the valve body
3 psig

10. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Current in the compressor circuit
It would cause the low-side pressure to decrease
It is used to control refrigerant pressure in the compressor crankcase

11. The internal overload of an air conditioning compressor senses winding temperature and...
Partially frosted evaporator and high superheat
An uninsulated TXV sensing bulb
Current in the compressor circuit
Low superheat

12. A customer calls with an insufficient cooling complaint on a 90
A low refrigerant charge
An increase in low-side pressure
The superheat will increase and the low-side pressure will decrease
Technician B

13. 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
Partially frosted evaporator and high superheat
Technician B
The internal overload is opened
An increase of air leakage from ductwork

14. 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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
High suction pressure and low superheat

15. 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...
('Y' and 'C') and ('G' and 'C')
Technician A is correct
Broken rings+broken valves+seized bearings
Condenser fans operating during a low ambient condition and a low suction pressure

16. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A bad thermostat
Condenser fans operating during a low ambient condition and a low suction pressure
A low refrigerant charge
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

17. 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
Condenser fans operating during a low ambient condition and a low suction pressure
Both technicians are incorrect
Lack of airflow
Current in the compressor circuit

18. What are three methods for controlling a system's high-side pressure during low ambient conditions...
High superheat and low discharge pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air

19. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
Technician B
An acid-core suction line drier
3 psig

20. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted
Whenever necessary

21. Air filters should be replaced...
Technician A is correct
An undercharge and low ambient conditions
Whenever necessary
Broken rings+broken valves+seized bearings

22. 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
Both technicians are correct
An open internal overload protector
Technician B
The superheat increases and the subcooling decreases

23. 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
The internal overload is opened
An undercharged system+insufficient airflow over the evaporator coil
It would cause the low-side pressure to decrease
Technician B

24. What component is most often the cause of a start capacitor failure...
Technician B
50-65
A start relay
High superheat and low discharge pressure

25. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Partially frosted evaporator and high superheat
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
Broken rings+broken valves+seized bearings

26. 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
Clean the condenser coil
Condenser fans operating during a low ambient condition and a low suction pressure
Current in the compressor circuit
A defective circuit breaker

27. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The external equalizer could be plugged
Broken rings+broken valves+seized bearings
An acid-core suction line drier

28. 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 bad thermostat
An uninsulated suction line and a restricted metering device
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B

29. What is the common cause of a compressor burnout...
'G' to 'C'
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

30. A commercial customer calls complaining that her rooftop air conditioning system is not operating. The technician arrives on the job and sets the thermostat to cooling - then notices that the indoor fan is not operating. The technician then sets the

31. Why is it unsafe to operate an air conditioning system with a low charge...
Both technicians are incorrect
Technician B
Rise more than normal
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

32. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
A low refrigerant charge
It would cause the low-side pressure to decrease
An undercharge and low ambient conditions

33. What are two problems that can cause an air conditioning system to have an excessively high superheat...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Flooding the condenser - cycling condenser fans - and dampering condenser air
An uninsulated suction line and a restricted metering device
Low voltage and a faulty start relay

34. 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
Lack of airflow
Technician B
Technician A
Low voltage and a faulty start relay

35. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An uninsulated suction line and a restricted metering device
A plugged filter drier
The external equalizer could be plugged

36. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
110-120
An increase in suction pressure and an increase in discharge pressure
It would cause the low-side pressure to decrease

37. Which of the following will cause excessive discharge pressures on an air conditioning system...
A start relay
Low superheat
The system has been overcharged+The system has air trapped in the condenser
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

38. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
110-120

39. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
Technician B
The sight glass is full of liquid+the sight glass is full of gas
Always have some liquid present in the bulb and diaphragm

40. 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
Current in the compressor circuit
An open internal overload protector
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

41. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
The superheat will increase and the low-side pressure will decrease
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A defective circuit breaker
Lack of airflow

42. 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
Both technicians are incorrect
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
It keeps a constant superheat in the evaporator

43. 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
Low discharge pressure - high suction pressure - and low amp draw
Technician B
A bad thermostat
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

44. A customer calls with an insufficient cooling complaint on a 90
Run with high head and high suction pressure
A vacuum test+oil traces around fittings+soap bubble solution
Both technicians are incorrect
Technician B

45. 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...
Broken rings+broken valves+seized bearings
A blown fuse
Flooding the condenser - cycling condenser fans - and dampering condenser air
It would cause the low-side pressure to decrease

46. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Run with high head and high suction pressure
High superheat and low discharge pressure
Broken rings+broken valves+seized bearings
A missing air filter+improper rotation of the indoor blower+blower too small

47. A liquid-charged TXV bulb will...
An increase of air leakage from ductwork
Always have some liquid present in the bulb and diaphragm
Contains a solenoid coil and one or more sets of contacts
The superheat increases and the subcooling decreases

48. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
The system has been overcharged+The system has air trapped in the condenser
An overcharged system
Technician A

49. What are the symptoms of an air conditioning system that has a low charge...
110-120
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The low-side pressure will decrease and the evaporator coil will be partially frosted
An undercharge and low ambient conditions

50. A system that is operating with a clear sight glass shows...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An increase of air leakage from ductwork
The sight glass is full of liquid+the sight glass is full of gas
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system