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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. 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
Technician B
The external equalizer could be plugged
Both technicians are incorrect
Flooding the condenser - cycling condenser fans - and dampering condenser air

2. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An overcharged system
A start relay
Low discharge pressure - high suction pressure - and low amp draw

3. A hard-start kit for an air conditioning system...
Increases starting torque
The internal overload is opened
Technician B
The system has been overcharged+The system has air trapped in the condenser

4. Air filters should be replaced...
Technician A is correct
An increase in suction pressure and an increase in discharge pressure
Whenever necessary
An acid-core suction line drier

5. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A vacuum test+oil traces around fittings+soap bubble solution
A missing air filter+improper rotation of the indoor blower+blower too small
High superheat and low discharge pressure

6. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
20 to 30
A missing air filter+improper rotation of the indoor blower+blower too small
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

7. 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...
Technician B
Both technicians are correct
Low voltage and a faulty start relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

8. 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
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Low superheat

9. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
20 to 30
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Low superheat
Technician B

10. 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
The discharge pressure increases and the amperage increases
The sensing bulb at a lower temperature than the valve body
A defective circuit breaker

11. What is the common cause of a compressor burnout...
An undercharge and low ambient conditions
Both technicians are correct
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A restricted metering device

12. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It is used to control refrigerant pressure in the compressor crankcase
A start relay
Low discharge pressure - high suction pressure - and low amp draw
It would cause the low-side pressure to decrease

13. 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...
Short cycling and insufficient dehumidification
High suction pressure and low superheat
Condenser fans operating during a low ambient condition and a low suction pressure
'G' to 'C'

14. 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
20 to 30
Short cycling and insufficient dehumidification
The external equalizer could be plugged
It is used to control refrigerant pressure in the compressor crankcase

15. What is the purpose of a CPR valve...
Condenser fans operating during a low ambient condition and a low suction pressure
The external equalizer could be plugged
An uninsulated suction line and a restricted metering device
It is used to control refrigerant pressure in the compressor crankcase

16. A customer calls with an insufficient cooling complaint on a 90
An undercharged system+insufficient airflow over the evaporator coil
Technician B
An uninsulated TXV sensing bulb
The system has been overcharged+The system has air trapped in the condenser

17. Superheat is found in an air conditioning system in the...
An increase of air leakage from ductwork
20 to 30
Evaporator and compressor
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

18. 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
A missing air filter+improper rotation of the indoor blower+blower too small
An uninsulated TXV sensing bulb
Technician B

19. Why is it unsafe to operate an air conditioning system with a low charge...
Increases starting torque
A start relay
'G' to 'C'
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

20. Which of the following will cause excessive discharge pressures on an air conditioning system...
Low superheat
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An overcharged system
It keeps a constant superheat in the evaporator

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
A bad thermostat
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Clean the condenser coil
Technician B

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
A bad thermostat
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An open internal overload protector

23. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An open internal overload protector
The superheat increases and the subcooling decreases
Always have some liquid present in the bulb and diaphragm

24. What is the purpose of an EPR valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A blown fuse
An undercharged system+insufficient airflow over the evaporator coil
50-65

25. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
3 psig
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

26. A system that uses a thermal electric expansion valve...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Whenever necessary
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

27. 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
An uninsulated suction line and a restricted metering device
Short cycling and insufficient dehumidification
Dirty condenser - bent condenser fins - and air recirculating over the condenser

28. The best description of a relay would be...
Bad compressor valve
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Bad compressor valve
Contains a solenoid coil and one or more sets of contacts

29. 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
It would cause the low-side pressure to decrease
Technician A
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Contains a solenoid coil and one or more sets of contacts

30. A customer calls with an insufficient cooling complaint on a 90
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An increase in low-side pressure
Technician B
A low refrigerant charge

31. A restricted air filter in an air conditioning system can be identified by...
Low superheat
('Y' and 'C') and ('G' and 'C')
Clean the condenser coil
The sight glass is full of liquid+the sight glass is full of gas

32. 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
It is used to control refrigerant pressure in the compressor crankcase
Technician A
An overcharged system

33. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The internal overload is opened
110-120
An overcharged system
An increase in suction pressure and an increase in discharge pressure

34. Which of the following is a possible cause for a compressor to overheat...
The internal overload is opened
Increases starting torque
Technician B
A low refrigerant charge

35. 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
Current in the compressor circuit
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A defective circuit breaker
A missing air filter+improper rotation of the indoor blower+blower too small

36. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are correct
20 to 30

37. Insufficient airflow can be caused by...
A sensing bulb improperly connected to the suction line
An increase of air leakage from ductwork
Low superheat
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

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...
The sensing bulb at a lower temperature than the valve body
Lack of airflow
An open internal overload protector
An acid-core suction line drier

39. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
An overcharged system
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
An increase of air leakage from ductwork

40. A restricted air filter in an air conditioning system can be identified by...
50-65
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Low superheat

41. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
A defective circuit breaker
An uninsulated TXV sensing bulb
Current in the compressor circuit

42. A commercial customer calls on a 90
An undercharge and low ambient conditions
The system has been overcharged+The system has air trapped in the condenser
Condenser fans operating during a low ambient condition and a low suction pressure
Both technicians are correct

43. What component is most often the cause of a start capacitor failure...
Both technicians are correct
A start relay
'G' to 'C'
Low superheat

44. The best description of a relay would be...
High suction pressure and low superheat
An increase of air leakage from ductwork
Technician B
Contains a solenoid coil and one or more sets of contacts

45. Which of the following could be the cause for a system's discharge and suction pressure being low...
An uninsulated TXV sensing bulb
A restricted metering device
Clean the condenser coil
Bad compressor valve

46. 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
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
('Y' and 'C') and ('G' and 'C')
The discharge pressure increases and the amperage increases

47. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Technician B
Low superheat
It is used to control refrigerant pressure in the compressor crankcase
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

48. Which of the following can cause excessive subcooling...
A restricted metering device
Both technicians are incorrect
Both technicians are correct
An overcharged system

49. Which of the following is a possible cause for a compressor to overheat...
The internal overload is opened
The sensing bulb at a lower temperature than the valve body
A low refrigerant charge
Technician B

50. 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
It keeps a constant superheat in the evaporator
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B