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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 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
3 psig
An uninsulated suction line and a restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small

2. When using a vapor-charged TXV bulb - it is necessary to have...
High superheat and low discharge pressure
A bad thermostat
The sensing bulb at a lower temperature than the valve body
An increase of air leakage from ductwork

3. 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...
A missing air filter+improper rotation of the indoor blower+blower too small
Both technicians are correct
The internal overload is opened
Rise more than normal

4. A system that uses a thermal electric expansion valve...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician A is correct
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

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
Condenser fans operating during a low ambient condition and a low suction pressure
Low discharge pressure - high suction pressure - and low amp draw
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

6. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
('Y' and 'C') and ('G' and 'C')
An acid-core suction line drier
Increases starting torque
A missing air filter+improper rotation of the indoor blower+blower too small

7. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Run with high head and high suction pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An increase in low-side pressure
An undercharged system+insufficient airflow over the evaporator coil

8. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Both technicians are incorrect
A start capacitor and a solid-state relay
Low discharge pressure - high suction pressure - and low amp draw
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

9. What problem or problems can cause low discharge and suction pressure...
Whenever necessary
An increase of air leakage from ductwork
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An undercharged system+insufficient airflow over the evaporator coil

10. What are common methods that are used for leak-testing a system...
A plugged filter drier
Bad compressor valve
Both technicians are incorrect
A vacuum test+oil traces around fittings+soap bubble solution

11. The temperature range of the suction line from an air conditioning system should be...
Both technicians are correct
It keeps a constant superheat in the evaporator
50-65
An uninsulated TXV sensing bulb

12. What is the common cause of a compressor burnout...
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
An increase in suction pressure and an increase in discharge pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

13. A commercial customer calls on a 90
It is used to control refrigerant pressure in the compressor crankcase
An undercharged system+insufficient airflow over the evaporator coil
Technician A
The system has been overcharged+The system has air trapped in the condenser

14. 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...
Partially frosted evaporator and high superheat
Low voltage and a faulty start relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The discharge pressure increases and the amperage increases

15. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A start relay
Run with high head and high suction pressure

16. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B

17. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Always have some liquid present in the bulb and diaphragm
An increase in low-side pressure
An uninsulated suction line and a restricted metering device

18. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Flooding the condenser - cycling condenser fans - and dampering condenser air
An acid-core suction line drier
The sight glass is full of liquid+the sight glass is full of gas
Partially frosted evaporator and high superheat

19. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Current in the compressor circuit
It would cause the low-side pressure to decrease
3 psig
The discharge pressure increases and the amperage increases

20. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An uninsulated TXV sensing bulb
Technician B
Evaporator and compressor

21. What problem can cause an increase of discharge pressure and an increase of suction pressure...
The external equalizer could be plugged
Flooding the condenser - cycling condenser fans - and dampering condenser air
An overcharged system
'G' to 'C'

22. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Broken rings+broken valves+seized bearings
It would cause the low-side pressure to decrease
The superheat will increase and the low-side pressure will decrease
An uninsulated suction line and a restricted metering device

23. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A restricted metering device
A restricted metering device
Contains a solenoid coil and one or more sets of contacts
Run with high head and high suction pressure

24. What are three methods for controlling a system's high-side pressure during low ambient conditions...
The system has been overcharged+The system has air trapped in the condenser
'G' to 'C'
Flooding the condenser - cycling condenser fans - and dampering condenser air
The superheat will increase and the low-side pressure will decrease

25. What are two common symptoms of refrigerant leaks in an air conditioning system...
An acid-core suction line drier
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Partially frosted evaporator and high superheat
Whenever necessary

26. 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...
Technician B
High superheat and low discharge pressure
Broken rings+broken valves+seized bearings
An undercharge and low ambient conditions

27. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A sensing bulb improperly connected to the suction line
A low refrigerant charge

28. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
It is used to control refrigerant pressure in the compressor crankcase
Technician B
A plugged filter drier
Condenser fans operating during a low ambient condition and a low suction pressure

29. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Both technicians are incorrect
Bad compressor valve
A start relay
50-65

30. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Run with high head and high suction pressure
The sight glass is full of liquid+the sight glass is full of gas
110-120
The system has been overcharged+The system has air trapped in the condenser

31. A hard-start kit for an air conditioning system...
Condenser fans operating during a low ambient condition and a low suction pressure
Low voltage and a faulty start relay
Increases starting torque
The low-side pressure will decrease and the evaporator coil will be partially frosted

32. 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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33. 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
Technician A
A blown fuse
High suction pressure and low superheat

34. Which of the following could be the cause for a system's discharge and suction pressure being low...
It keeps a constant superheat in the evaporator
Technician B
A plugged filter drier
A restricted metering device

35. 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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36. 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
Technician A
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
A sensing bulb improperly connected to the suction line

37. Which of the following can cause excessive subcooling...
Run with high head and high suction pressure
An overcharged system
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B

38. A system that is operating with a clear sight glass shows...
Always have some liquid present in the bulb and diaphragm
The sight glass is full of liquid+the sight glass is full of gas
It would cause the low-side pressure to decrease
A sensing bulb improperly connected to the suction line

39. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
Technician B
A plugged filter drier
('Y' and 'C') and ('G' and 'C')

40. Which of the following could be the cause for a system's discharge and suction pressure being low...
A vacuum test+oil traces around fittings+soap bubble solution
Always have some liquid present in the bulb and diaphragm
An uninsulated suction line and a restricted metering device
A restricted metering device

41. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
A restricted metering device
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It is used to control refrigerant pressure in the compressor crankcase
Technician B

42. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
It would cause the low-side pressure to decrease
'G' to 'C'
Partially frosted evaporator and high superheat

43. What causes the automatic expansion valve to close...
('Y' and 'C') and ('G' and 'C')
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Whenever necessary
An increase in low-side pressure

44. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
It keeps a constant superheat in the evaporator
High suction pressure and low superheat
Short cycling and insufficient dehumidification
An undercharge and low ambient conditions

45. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Lack of airflow
An increase of air leakage from ductwork
Always have some liquid present in the bulb and diaphragm
It would cause the low-side pressure to decrease

46. What are the symptoms of an air conditioning system that has a low charge...
Rise more than normal
It is used to control refrigerant pressure in the compressor crankcase
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B

47. Superheat is found in an air conditioning system in the...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A start relay
An overcharged system
Evaporator and compressor

48. 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 external equalizer could be plugged
The superheat increases and the subcooling decreases
Technician B
An open internal overload protector

49. 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
It is used to control refrigerant pressure in the compressor crankcase
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Dirty condenser - bent condenser fins - and air recirculating over the condenser

50. What are the operating pressures of an oil pressure safety switch...
An increase of air leakage from ductwork
An overcharged system
A restricted metering device
The oil pump pressure and the crankcase pressure