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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. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
An uninsulated suction line and a restricted metering device
An acid-core suction line drier
Run with high head and high suction pressure
The internal overload is opened

2. Which of the following can cause low superheat in a TXV system...
A start capacitor and a solid-state relay
Both technicians are incorrect
An uninsulated TXV sensing bulb
The sight glass is full of liquid+the sight glass is full of gas

3. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An undercharged system+insufficient airflow over the evaporator coil
Technician A
Flooding the condenser - cycling condenser fans - and dampering condenser air

4. 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
3 psig
Current in the compressor circuit
Bad compressor valve

5. 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
Always have some liquid present in the bulb and diaphragm
The sensing bulb at a lower temperature than the valve body
Technician A is correct

6. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
The external equalizer could be plugged
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A low refrigerant charge

7. The best description of a relay would be...
Both technicians are incorrect
It keeps a constant superheat in the evaporator
Contains a solenoid coil and one or more sets of contacts
Evaporator and compressor

8. What type of problems can be caused by an oversized air conditioning system...
An increase in low-side pressure
Technician A
Evaporator and compressor
Short cycling and insufficient dehumidification

9. 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

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10. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
3 psig
A sensing bulb improperly connected to the suction line
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

11. 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
An increase in suction pressure and an increase in discharge pressure
Technician B
The sight glass is full of liquid+the sight glass is full of gas

12. 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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13. What problem or problems can cause low discharge and suction pressure...
Bad compressor valve
An undercharged system+insufficient airflow over the evaporator coil
A start relay
Technician B

14. What is the purpose of the TXV...
An increase in low-side pressure
Lack of airflow
It keeps a constant superheat in the evaporator
3 psig

15. Air filters should be replaced...
It would cause the low-side pressure to decrease
A defective circuit breaker
Lack of airflow
Whenever necessary

16. The internal overload of an air conditioning compressor senses winding temperature and...
Partially frosted evaporator and high superheat
An increase of air leakage from ductwork
A plugged filter drier
Current in the compressor circuit

17. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A blown fuse
The discharge pressure increases and the amperage increases

18. Which of the following is a common cause of an excessively low superheat on a TXV system...
Partially frosted evaporator and high superheat
Technician A is correct
An open internal overload protector
A sensing bulb improperly connected to the suction line

19. 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
'G' to 'C'
The superheat increases and the subcooling decreases
Technician B
An overcharged system

20. What causes the automatic expansion valve to close...
A plugged filter drier
Technician B
An increase in low-side pressure
The superheat will increase and the low-side pressure will decrease

21. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Technician A
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
110-120
The superheat increases and the subcooling decreases

22. What are the symptoms of an air conditioning system that has a low charge...
The low-side pressure will decrease and the evaporator coil will be partially frosted
High superheat and low discharge pressure
A plugged filter drier
Dirty condenser - bent condenser fins - and air recirculating over the condenser

23. Which of the following is a possible cause for a compressor to overheat...
An open internal overload protector
A low refrigerant charge
Technician B
Broken rings+broken valves+seized bearings

24. 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
A blown fuse
Low discharge pressure - high suction pressure - and low amp draw
An acid-core suction line drier
Technician B

25. 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
A missing air filter+improper rotation of the indoor blower+blower too small
It is used to control refrigerant pressure in the compressor crankcase
Low superheat

26. 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...
A sensing bulb improperly connected to the suction line
Low voltage and a faulty start relay
Technician B
A start capacitor and a solid-state relay

27. Which of the following could be the cause for a system's discharge and suction pressure being low...
'G' to 'C'
High superheat and low discharge pressure
Rise more than normal
A restricted metering device

28. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
Short cycling and insufficient dehumidification
Condenser fans operating during a low ambient condition and a low suction pressure
An overcharged system

29. Why is it unsafe to operate an air conditioning system with a low charge...
A defective circuit breaker
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Run with high head and high suction pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

30. What is the purpose of a CPR valve...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It is used to control refrigerant pressure in the compressor crankcase
Bad compressor valve

31. 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
A start relay
The external equalizer could be plugged
The discharge pressure increases and the amperage increases
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

32. A system that is operating with a clear sight glass shows...
A sensing bulb improperly connected to the suction line
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The sight glass is full of liquid+the sight glass is full of gas
A start capacitor and a solid-state relay

33. 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...
Bad compressor valve
An uninsulated suction line and a restricted metering device
A start relay
A blown fuse

34. What component is most often the cause of a start capacitor failure...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An overcharged system
A start relay
Whenever necessary

35. 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
The sensing bulb at a lower temperature than the valve body
An open internal overload protector
Evaporator and compressor
An acid-core suction line drier

36. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A vacuum test+oil traces around fittings+soap bubble solution
Both technicians are incorrect
Low voltage and a faulty start relay

37. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Low superheat
A sensing bulb improperly connected to the suction line
3 psig
Both technicians are correct

38. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
Low discharge pressure - high suction pressure - and low amp draw
The superheat will increase and the low-side pressure will decrease
Contains a solenoid coil and one or more sets of contacts

39. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
50-65
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It is used to control refrigerant pressure in the compressor crankcase
Bad compressor valve

40. What type of problems can be caused by an oversized air conditioning system...
Always have some liquid present in the bulb and diaphragm
Short cycling and insufficient dehumidification
3 psig
A bad thermostat

41. What are three methods for controlling a system's high-side pressure during low ambient conditions...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
'G' to 'C'
Flooding the condenser - cycling condenser fans - and dampering condenser air
A missing air filter+improper rotation of the indoor blower+blower too small

42. What are three methods for controlling a system's high-side pressure during low ambient conditions...
It keeps a constant superheat in the evaporator
A low refrigerant charge
Broken rings+broken valves+seized bearings
Flooding the condenser - cycling condenser fans - and dampering condenser air

43. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Bad compressor valve
An open internal overload protector
The low-side pressure will decrease and the evaporator coil will be partially frosted
The discharge pressure increases and the amperage increases

44. 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 B
Technician A is correct
Flooding the condenser - cycling condenser fans - and dampering condenser air
Low discharge pressure - high suction pressure - and low amp draw

45. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Low superheat
The external equalizer could be plugged
An increase in suction pressure and an increase in discharge pressure

46. Superheat is found in an air conditioning system in the...
Evaporator and compressor
A vacuum test+oil traces around fittings+soap bubble solution
('Y' and 'C') and ('G' and 'C')
An open internal overload protector

47. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
The sight glass is full of liquid+the sight glass is full of gas
The sensing bulb at a lower temperature than the valve body
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

48. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Run with high head and high suction pressure
Whenever necessary
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

49. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Broken rings+broken valves+seized bearings
Lack of airflow

50. 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
3 psig
A vacuum test+oil traces around fittings+soap bubble solution
An uninsulated suction line and a restricted metering device