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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 can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
('Y' and 'C') and ('G' and 'C')
A bad thermostat
The superheat increases and the subcooling decreases

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 increase in suction pressure and an increase in discharge pressure
Rise more than normal
The oil pump pressure and the crankcase pressure

3. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Partially frosted evaporator and high superheat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Lack of airflow
Low discharge pressure - high suction pressure - and low amp draw

4. Why is it unsafe to operate an air conditioning system with a low charge...
High suction pressure and low superheat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician A
High superheat and low discharge pressure

5. 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
The sensing bulb at a lower temperature than the valve body
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician A is correct

6. 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 B
Technician A
The external equalizer could be plugged
Short cycling and insufficient dehumidification

7. What is the purpose of the TXV...
An increase in suction pressure and an increase in discharge pressure
Technician B
It keeps a constant superheat in the evaporator
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

8. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Low discharge pressure - high suction pressure - and low amp draw
Technician B
An uninsulated suction line and a restricted metering device
Contains a solenoid coil and one or more sets of contacts

9. What type of problems can be caused by an oversized air conditioning system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Short cycling and insufficient dehumidification
Whenever necessary
A restricted metering device

10. A hard-start kit consists of...
'G' to 'C'
A start capacitor and a solid-state relay
An undercharge and low ambient conditions
Evaporator and compressor

11. Insufficient airflow can be caused by...
A start capacitor and a solid-state relay
An increase of air leakage from ductwork
A start capacitor and a solid-state relay
An uninsulated TXV sensing bulb

12. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
A defective circuit breaker
Rise more than normal
A start relay
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

13. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
Technician B
Increases starting torque
An undercharged system+insufficient airflow over the evaporator coil

14. What is the common cause of a compressor burnout...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The superheat will increase and the low-side pressure will decrease
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The internal overload is opened

15. 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
High suction pressure and low superheat
Both technicians are incorrect
Technician B
Both technicians are correct

16. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
The discharge pressure increases and the amperage increases
An increase in low-side pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

17. The temperature range of the suction line from an air conditioning system should be...
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
Current in the compressor circuit
50-65

18. 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
Rise more than normal
Technician B
The oil pump pressure and the crankcase pressure
Clean the condenser coil

19. 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
Increases starting torque
An undercharged system+insufficient airflow over the evaporator coil
Both technicians are incorrect

20. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
An increase in low-side pressure
Technician B
110-120
Rise more than normal

21. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Always have some liquid present in the bulb and diaphragm
Broken rings+broken valves+seized bearings
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

22. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Technician B
Run with high head and high suction pressure
A vacuum test+oil traces around fittings+soap bubble solution
Both technicians are incorrect

23. Which of the following can cause excessive subcooling...
The oil pump pressure and the crankcase pressure
A defective circuit breaker
Technician B
An overcharged system

24. 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
The superheat will increase and the low-side pressure will decrease
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B

25. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Low discharge pressure - high suction pressure - and low amp draw
3 psig
It keeps a constant superheat in the evaporator
Technician B

26. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Low superheat
Run with high head and high suction pressure

27. 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
A vacuum test+oil traces around fittings+soap bubble solution
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Low voltage and a faulty start relay

28. A restricted air filter in an air conditioning system can be identified by...
Low superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted
Partially frosted evaporator and high superheat
A plugged filter drier

29. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The system has been overcharged+The system has air trapped in the condenser
An undercharged system+insufficient airflow over the evaporator coil
A start capacitor and a solid-state relay
An increase in suction pressure and an increase in discharge pressure

30. 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
The external equalizer could be plugged
A restricted metering device
An undercharged system+insufficient airflow over the evaporator coil
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

31. 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...
The oil pump pressure and the crankcase pressure
An increase of air leakage from ductwork
High superheat and low discharge pressure
Always have some liquid present in the bulb and diaphragm

32. What are the symptoms of an air conditioning system that has a low charge...
Technician A is correct
The low-side pressure will decrease and the evaporator coil will be partially frosted
Low discharge pressure - high suction pressure - and low amp draw
An increase in suction pressure and an increase in discharge pressure

33. What are common methods that are used for leak-testing a system...
Technician B
An overcharged system
A vacuum test+oil traces around fittings+soap bubble solution
An undercharge and low ambient conditions

34. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
Broken rings+broken valves+seized bearings
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A low refrigerant charge

35. What is the purpose of an EPR valve...
Lack of airflow
('Y' and 'C') and ('G' and 'C')
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
110-120

36. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
Technician A
High superheat and low discharge pressure
Low voltage and a faulty start relay

37. What component is most often the cause of a start capacitor failure...
Technician B
A start relay
A sensing bulb improperly connected to the suction line
The external equalizer could be plugged

38. Which of the following can cause excessive subcooling...
An overcharged system
The sensing bulb at a lower temperature than the valve body
Flooding the condenser - cycling condenser fans - and dampering condenser air
Short cycling and insufficient dehumidification

39. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Technician A
Flooding the condenser - cycling condenser fans - and dampering condenser air
Both technicians are incorrect
The superheat will increase and the low-side pressure will decrease

40. Which of the following will cause excessive discharge pressures on an air conditioning system...
A low refrigerant charge
The superheat increases and the subcooling decreases
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Both technicians are incorrect

41. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Broken rings+broken valves+seized bearings
A plugged filter drier
It keeps a constant superheat in the evaporator
'G' to 'C'

42. Which of the following is a possible cause for a compressor to overheat...
A blown fuse
A low refrigerant charge
Bad compressor valve
Broken rings+broken valves+seized bearings

43. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Always have some liquid present in the bulb and diaphragm
An overcharged system
The internal overload is opened
20 to 30

44. Air filters should be replaced...
Always have some liquid present in the bulb and diaphragm
Whenever necessary
A bad thermostat
An acid-core suction line drier

45. 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
Low superheat
Condenser fans operating during a low ambient condition and a low suction pressure
High superheat and low discharge pressure

46. 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
An acid-core suction line drier
Technician B
Technician B

47. 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
Technician B
A restricted metering device
A bad thermostat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

48. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
High suction pressure and low superheat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
('Y' and 'C') and ('G' and 'C')

49. What are the operating pressures of an oil pressure safety switch...
Always have some liquid present in the bulb and diaphragm
It keeps a constant superheat in the evaporator
The oil pump pressure and the crankcase pressure
The discharge pressure increases and the amperage increases

50. 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 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
Short cycling and insufficient dehumidification
The internal overload is opened