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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. A hard-start kit consists of...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A start capacitor and a solid-state relay
Technician B
110-120

2. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A defective circuit breaker
The superheat increases and the subcooling decreases
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

3. Which of the following can cause low superheat in a TXV system...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A defective circuit breaker
An uninsulated TXV sensing bulb
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

4. 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
Low superheat
It would cause the low-side pressure to decrease
An undercharge and low ambient conditions
Both technicians are correct

5. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The sight glass is full of liquid+the sight glass is full of gas
A restricted metering device
Low discharge pressure - high suction pressure - and low amp draw
An increase of air leakage from ductwork

6. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An increase in low-side pressure
Low voltage and a faulty start relay
A missing air filter+improper rotation of the indoor blower+blower too small
The discharge pressure increases and the amperage increases

7. What component is most often the cause of a start capacitor failure...
The superheat will increase and the low-side pressure will decrease
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
A start relay

8. 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...
Increases starting torque
Low voltage and a faulty start relay
50-65
Clean the condenser coil

9. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
A defective circuit breaker
Both technicians are incorrect
Contains a solenoid coil and one or more sets of contacts

10. 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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11. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Current in the compressor circuit
It keeps a constant superheat in the evaporator
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

12. A hard-start kit for an air conditioning system...
Increases starting torque
High superheat and low discharge pressure
The superheat increases and the subcooling decreases
Low discharge pressure - high suction pressure - and low amp draw

13. Why is it unsafe to operate an air conditioning system with a low charge...
An overcharged system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A bad thermostat
A defective circuit breaker

14. 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 plugged filter drier
Technician B
The internal overload is opened
Whenever necessary

15. 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...
An overcharged system
110-120
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Condenser fans operating during a low ambient condition and a low suction pressure

16. What are the symptoms of an air conditioning system that has a low charge...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted
Short cycling and insufficient dehumidification
('Y' and 'C') and ('G' and 'C')

17. The internal overload of an air conditioning compressor senses winding temperature and...
An undercharge and low ambient conditions
It is used to control refrigerant pressure in the compressor crankcase
Current in the compressor circuit
Technician B

18. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Whenever necessary
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

19. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
Evaporator and compressor
Low discharge pressure - high suction pressure - and low amp draw
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

20. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
A plugged filter drier
High suction pressure and low superheat
A low refrigerant charge

21. What component is most often the cause of a start capacitor failure...
Both technicians are correct
Contains a solenoid coil and one or more sets of contacts
A start relay
50-65

22. Which of the following will cause excessive discharge pressures on an air conditioning system...
A vacuum test+oil traces around fittings+soap bubble solution
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Both technicians are correct

23. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An overcharged system
Clean the condenser coil

24. 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
Broken rings+broken valves+seized bearings
50-65
20 to 30
Technician B

25. When using a vapor-charged TXV bulb - it is necessary to have...
An acid-core suction line drier
The external equalizer could be plugged
The sensing bulb at a lower temperature than the valve body
Contains a solenoid coil and one or more sets of contacts

26. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
('Y' and 'C') and ('G' and 'C')
A start relay
An undercharged system+insufficient airflow over the evaporator coil

27. What are common methods that are used for leak-testing a system...
High superheat and low discharge pressure
Clean the condenser coil
The sight glass is full of liquid+the sight glass is full of gas
A vacuum test+oil traces around fittings+soap bubble solution

28. The internal overload of an air conditioning compressor senses winding temperature and...
An uninsulated suction line and a restricted metering device
Rise more than normal
The external equalizer could be plugged
Current in the compressor circuit

29. 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
The external equalizer could be plugged
Low discharge pressure - high suction pressure - and low amp draw
The low-side pressure will decrease and the evaporator coil will be partially frosted

30. 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
An uninsulated TXV sensing bulb
An uninsulated suction line and a restricted metering device
Technician B
The superheat increases and the subcooling decreases

31. 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
A plugged filter drier
A blown fuse
The sight glass is full of liquid+the sight glass is full of gas

32. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Technician A is correct
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
Dirty condenser - bent condenser fins - and air recirculating over the condenser

33. Which of the following is a possible cause for a compressor to overheat...
Technician B
High suction pressure and low superheat
A low refrigerant charge
A blown fuse

34. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Technician A
Both technicians are incorrect
20 to 30
The discharge pressure increases and the amperage increases

35. What causes the automatic expansion valve to close...
An increase in low-side pressure
Short cycling and insufficient dehumidification
An undercharge and low ambient conditions
Both technicians are incorrect

36. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The discharge pressure increases and the amperage increases
Always have some liquid present in the bulb and diaphragm
Both technicians are incorrect

37. 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
It keeps a constant superheat in the evaporator
('Y' and 'C') and ('G' and 'C')
Technician A is correct
Clean the condenser coil

38. 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 air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A sensing bulb improperly connected to the suction line
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

39. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
High superheat and low discharge pressure
High superheat and low discharge pressure
Low discharge pressure - high suction pressure - and low amp draw
It is used to control refrigerant pressure in the compressor crankcase

40. 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
Clean the condenser coil
Both technicians are correct
A restricted metering device
It would cause the low-side pressure to decrease

41. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
50-65
The discharge pressure increases and the amperage increases
A bad thermostat

42. 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
Current in the compressor circuit
The external equalizer could be plugged
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
High superheat and low discharge pressure

43. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Increases starting torque
A start relay
A bad thermostat

44. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Broken rings+broken valves+seized bearings
The sensing bulb at a lower temperature than the valve body
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

45. 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 sensing bulb improperly connected to the suction line
Technician A is correct
The superheat increases and the subcooling decreases
A defective circuit breaker

46. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Increases starting torque
Flooding the condenser - cycling condenser fans - and dampering condenser air
Increases starting torque
Condenser fans operating during a low ambient condition and a low suction pressure

47. What is the purpose of a CPR valve...
Low voltage and a faulty start relay
It keeps a constant superheat in the evaporator
It is used to control refrigerant pressure in the compressor crankcase
The superheat will increase and the low-side pressure will decrease

48. A system that is operating with a clear sight glass shows...
Technician B
('Y' and 'C') and ('G' and 'C')
The sight glass is full of liquid+the sight glass is full of gas
The low-side pressure will decrease and the evaporator coil will be partially frosted

49. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The system has been overcharged+The system has air trapped in the condenser
An increase in low-side pressure

50. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
An acid-core suction line drier
A start capacitor and a solid-state relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A vacuum test+oil traces around fittings+soap bubble solution