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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 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
Technician A
A start relay
Clean the condenser coil

2. A compressor having tight bearings would cause the current value to...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Both technicians are incorrect
Partially frosted evaporator and high superheat
Rise more than normal

3. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
An overcharged system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician A is correct

4. What is the common cause of a compressor burnout...
Technician A is correct
An increase of air leakage from ductwork
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Always have some liquid present in the bulb and diaphragm

5. A system that uses a thermal electric expansion valve...
Lack of airflow
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician A

6. 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
Low voltage and a faulty start relay
An acid-core suction line drier
The external equalizer could be plugged
Partially frosted evaporator and high superheat

7. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Low voltage and a faulty start relay
A restricted metering device
The discharge pressure increases and the amperage increases
Technician A

8. Why is it unsafe to operate an air conditioning system with a low charge...
Evaporator and compressor
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
110-120
Increases starting torque

9. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The discharge pressure increases and the amperage increases
Increases starting torque
An increase in low-side pressure

10. 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
An increase in low-side pressure
Clean the condenser coil
Both technicians are correct
The superheat increases and the subcooling decreases

11. 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
The sensing bulb at a lower temperature than the valve body
50-65
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B

12. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An increase in suction pressure and an increase in discharge pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

13. The temperature range of the suction line from an air conditioning system should be...
The sensing bulb at a lower temperature than the valve body
Current in the compressor circuit
50-65
An uninsulated suction line and a restricted metering device

14. 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 sight glass is full of liquid+the sight glass is full of gas
Short cycling and insufficient dehumidification
Whenever necessary

15. What problem or problems can cause low discharge and suction pressure...
It would cause the low-side pressure to decrease
An undercharged system+insufficient airflow over the evaporator coil
High superheat and low discharge pressure
A start capacitor and a solid-state relay

16. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
The superheat will increase and the low-side pressure will decrease
Bad compressor valve
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

17. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
A blown fuse
Technician B
The superheat increases and the subcooling decreases
Technician A is correct

18. 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
Low discharge pressure - high suction pressure - and low amp draw
A defective circuit breaker
A bad thermostat
Condenser fans operating during a low ambient condition and a low suction pressure

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
An increase in low-side pressure
20 to 30
Technician B
An increase in suction pressure and an increase in discharge pressure

20. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An increase in low-side pressure
Condenser fans operating during a low ambient condition and a low suction pressure

21. The internal overload of an air conditioning compressor senses winding temperature and...
20 to 30
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Current in the compressor circuit
Low voltage and a faulty start relay

22. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It would cause the low-side pressure to decrease
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A low refrigerant charge
An increase of air leakage from ductwork

23. What is the purpose of an EPR valve...
The sight glass is full of liquid+the sight glass is full of gas
A vacuum test+oil traces around fittings+soap bubble solution
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A plugged filter drier

24. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
An undercharged system+insufficient airflow over the evaporator coil
Low superheat
High suction pressure and low superheat
Short cycling and insufficient dehumidification

25. 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
A vacuum test+oil traces around fittings+soap bubble solution
A plugged filter drier
An acid-core suction line drier
Technician B

26. A system that uses a thermal electric expansion valve...
A blown fuse
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An undercharge and low ambient conditions

27. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small
A low refrigerant charge
The superheat will increase and the low-side pressure will decrease

28. A hard-start kit for an air conditioning system...
Increases starting torque
An uninsulated TXV sensing bulb
Rise more than normal
Run with high head and high suction pressure

29. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Both technicians are incorrect
It keeps a constant superheat in the evaporator
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

30. 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...
Low voltage and a faulty start relay
The oil pump pressure and the crankcase pressure
An increase in low-side pressure
An undercharge and low ambient conditions

31. What are common methods that are used for leak-testing a system...
Condenser fans operating during a low ambient condition and a low suction pressure
Both technicians are incorrect
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A vacuum test+oil traces around fittings+soap bubble solution

32. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
20 to 30
An open internal overload protector

33. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
The internal overload is opened
Clean the condenser coil
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

34. 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
Bad compressor valve
A low refrigerant charge
A blown fuse
Technician B

35. Which of the following can cause excessive subcooling...
An overcharged system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system has been overcharged+The system has air trapped in the condenser
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

36. 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...
Both technicians are incorrect
Condenser fans operating during a low ambient condition and a low suction pressure
Increases starting torque
A blown fuse

37. What causes the automatic expansion valve to close...
A start relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An increase in low-side pressure
The discharge pressure increases and the amperage increases

38. 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
Broken rings+broken valves+seized bearings
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
Flooding the condenser - cycling condenser fans - and dampering condenser air

39. A customer calls and says that her air conditioning system is not cooling properly. Upon arrival - a technician notices that the suction line and compressor have frost buildup. Technician A says that the problem is probably a low charge. Technician B
An increase in suction pressure and an increase in discharge pressure
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The superheat will increase and the low-side pressure will decrease

40. The best description of a relay would be...
Technician B
Contains a solenoid coil and one or more sets of contacts
Technician B
Rise more than normal

41. Air filters should be replaced...
A defective circuit breaker
Whenever necessary
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An open internal overload protector

42. When using a vapor-charged TXV bulb - it is necessary to have...
A restricted metering device
The sensing bulb at a lower temperature than the valve body
The low-side pressure will decrease and the evaporator coil will be partially frosted
An acid-core suction line drier

43. 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
Both technicians are incorrect
A low refrigerant charge
Technician B
An overcharged system

44. 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 sensing bulb improperly connected to the suction line
('Y' and 'C') and ('G' and 'C')
The internal overload is opened
Technician B

45. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
It would cause the low-side pressure to decrease
110-120
Contains a solenoid coil and one or more sets of contacts
Flooding the condenser - cycling condenser fans - and dampering condenser air

46. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A defective circuit breaker
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
Both technicians are incorrect

47. What is the purpose of a CPR valve...
An undercharged system+insufficient airflow over the evaporator coil
It is used to control refrigerant pressure in the compressor crankcase
Short cycling and insufficient dehumidification
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...
An increase in low-side pressure
Run with high head and high suction pressure
High suction pressure and low superheat
The sight glass is full of liquid+the sight glass is full of gas

49. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Condenser fans operating during a low ambient condition and a low suction pressure
Low discharge pressure - high suction pressure - and low amp draw
Technician A is correct
Dirty condenser - bent condenser fins - and air recirculating over the condenser

50. What type of problems can be caused by an oversized air conditioning system...
Rise more than normal
Short cycling and insufficient dehumidification
A start relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

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