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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 problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
A plugged filter drier
Contains a solenoid coil and one or more sets of contacts
Whenever necessary

2. 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...
Partially frosted evaporator and high superheat
110-120
A plugged filter drier
High superheat and low discharge pressure

3. Which of the following is a possible cause for a compressor to overheat...
High superheat and low discharge pressure
20 to 30
A low refrigerant charge
The sensing bulb at a lower temperature than the valve body

4. What are two common symptoms of refrigerant leaks in an air conditioning system...
An uninsulated TXV sensing bulb
Partially frosted evaporator and high superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Both technicians are incorrect

5. 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
An increase in suction pressure and an increase in discharge pressure
An overcharged system
The external equalizer could be plugged
It would cause the low-side pressure to decrease

6. Superheat is found in an air conditioning system in the...
The superheat increases and the subcooling decreases
Increases starting torque
Current in the compressor circuit
Evaporator and compressor

7. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An increase in low-side pressure

8. 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
Technician B
A defective circuit breaker
A low refrigerant charge
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

9. Which of the following will cause excessive discharge pressures on an air conditioning system...
The oil pump pressure and the crankcase pressure
Both technicians are correct
High suction pressure and low superheat
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

10. Which of the following can cause excessive subcooling...
Partially frosted evaporator and high superheat
An overcharged system
An uninsulated TXV sensing bulb
The oil pump pressure and the crankcase pressure

11. 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
Technician B
It is used to control refrigerant pressure in the compressor crankcase
Both technicians are incorrect

12. The temperature range of the suction line from an air conditioning system should be...
Both technicians are correct
The superheat increases and the subcooling decreases
50-65
Technician B

13. What problem or problems can cause low discharge and suction pressure...
A sensing bulb improperly connected to the suction line
Clean the condenser coil
An undercharged system+insufficient airflow over the evaporator coil
Broken rings+broken valves+seized bearings

14. 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 superheat will increase and the low-side pressure will decrease
20 to 30
A missing air filter+improper rotation of the indoor blower+blower too small
An open internal overload protector

15. A liquid-charged TXV bulb will...
An uninsulated TXV sensing bulb
Always have some liquid present in the bulb and diaphragm
An increase in low-side pressure
Technician B

16. What type of problems can be caused by an oversized air conditioning system...
A missing air filter+improper rotation of the indoor blower+blower too small
Current in the compressor circuit
Condenser fans operating during a low ambient condition and a low suction pressure
Short cycling and insufficient dehumidification

17. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
Partially frosted evaporator and high superheat

18. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A sensing bulb improperly connected to the suction line
High superheat and low discharge pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
20 to 30

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...
An undercharged system+insufficient airflow over the evaporator coil
An uninsulated TXV sensing bulb
Low voltage and a faulty start relay
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

20. 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 A is correct
A bad thermostat
A vacuum test+oil traces around fittings+soap bubble solution
A start relay

21. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
An overcharged system
50-65
Technician A is correct
3 psig

22. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The system has been overcharged+The system has air trapped in the condenser
Low discharge pressure - high suction pressure - and low amp draw
Partially frosted evaporator and high superheat
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

23. A commercial customer calls on a 90
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The superheat will increase and the low-side pressure will decrease
Both technicians are incorrect
The system has been overcharged+The system has air trapped in the condenser

24. Why is it unsafe to operate an air conditioning system with a low charge...
A sensing bulb improperly connected to the suction line
It would cause the low-side pressure to decrease
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Clean the condenser coil

25. Which of the following will cause excessive discharge pressures on an air conditioning system...
Both technicians are incorrect
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Flooding the condenser - cycling condenser fans - and dampering condenser air

26. 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
Run with high head and high suction pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Both technicians are correct
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

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
An increase of air leakage from ductwork
Technician B
A restricted metering device
It keeps a constant superheat in the evaporator

28. The internal overload of an air conditioning compressor senses winding temperature and...
A bad thermostat
Both technicians are incorrect
Current in the compressor circuit
Clean the condenser coil

29. What causes the automatic expansion valve to close...
('Y' and 'C') and ('G' and 'C')
The internal overload is opened
An increase in low-side pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

30. When troubleshooting a split-system air conditioner - it is found that the compressor motor is humming but not starting. Technician A says that it could be an open internal overload protector. Technician B says that it could be a blown fuse. Which te
High suction pressure and low superheat
Both technicians are incorrect
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air

31. A customer who owns a split air conditioning system complains that his system has been running but his house doesn't seem to be cooling properly. When the service technician arrives on the job - he or she finds that the indoor blower is operating and
Technician B
Clean the condenser coil
A sensing bulb improperly connected to the suction line
Evaporator and compressor

32. 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
It keeps a constant superheat in the evaporator
Both technicians are correct
The sensing bulb at a lower temperature than the valve body
Short cycling and insufficient dehumidification

33. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
The internal overload is opened
The system has been overcharged+The system has air trapped in the condenser
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

34. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
Both technicians are correct
Dirty condenser - bent condenser fins - and air recirculating over the condenser

35. 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
20 to 30
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Whenever necessary

36. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Bad compressor valve
A vacuum test+oil traces around fittings+soap bubble solution
The oil pump pressure and the crankcase pressure

37. What is the purpose of a CPR valve...
Always have some liquid present in the bulb and diaphragm
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It is used to control refrigerant pressure in the compressor crankcase
'G' to 'C'

38. 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
Technician B
Technician B
Short cycling and insufficient dehumidification

39. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
Low voltage and a faulty start relay
Clean the condenser coil
It keeps a constant superheat in the evaporator

40. When using a vapor-charged TXV bulb - it is necessary to have...
The discharge pressure increases and the amperage increases
Rise more than normal
An increase in suction pressure and an increase in discharge pressure
The sensing bulb at a lower temperature than the valve body

41. 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...
20 to 30
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Condenser fans operating during a low ambient condition and a low suction pressure
Always have some liquid present in the bulb and diaphragm

42. What component is most often the cause of a start capacitor failure...
Short cycling and insufficient dehumidification
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician A
A start relay

43. 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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44. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A plugged filter drier
Short cycling and insufficient dehumidification
A missing air filter+improper rotation of the indoor blower+blower too small

45. A hard-start kit for an air conditioning system...
A low refrigerant charge
Bad compressor valve
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Increases starting torque

46. 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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Always have some liquid present in the bulb and diaphragm
The sight glass is full of liquid+the sight glass is full of gas
Technician B

47. 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
Low superheat
The superheat will increase and the low-side pressure will decrease
Technician B
A blown fuse

48. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Technician B
An increase of air leakage from ductwork
Increases starting torque
3 psig

49. A restricted air filter in an air conditioning system can be identified by...
Short cycling and insufficient dehumidification
A dirty condenser - recirculation of condenser air - and a defective condenser fan
20 to 30
Low superheat

50. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
Both technicians are correct
It keeps a constant superheat in the evaporator
Low discharge pressure - high suction pressure - and low amp draw