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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 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 oil pump pressure and the crankcase pressure
A sensing bulb improperly connected to the suction line
Technician B
An overcharged system

2. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Low voltage and a faulty start relay
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
An undercharge and low ambient conditions

3. 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...
Both technicians are incorrect
Condenser fans operating during a low ambient condition and a low suction pressure
'G' to 'C'
Both technicians are incorrect

4. 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
Contains a solenoid coil and one or more sets of contacts
An overcharged system
A blown fuse

5. 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
Technician B
110-120

6. 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
Run with high head and high suction pressure
High superheat and low discharge pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

7. A customer calls with an insufficient cooling complaint on a 90
Technician B
An undercharge and low ambient conditions
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A sensing bulb improperly connected to the suction line

8. 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
An open internal overload protector
Broken rings+broken valves+seized bearings
'G' to 'C'
Always have some liquid present in the bulb and diaphragm

9. 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 dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Lack of airflow
Evaporator and compressor
The internal overload is opened

10. 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
High superheat and low discharge pressure
Low voltage and a faulty start relay
Technician B
The sensing bulb at a lower temperature than the valve body

11. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A start capacitor and a solid-state relay
The sight glass is full of liquid+the sight glass is full of gas
Flooding the condenser - cycling condenser fans - and dampering condenser air
'G' to 'C'

12. A liquid-charged TXV bulb will...
A bad thermostat
Always have some liquid present in the bulb and diaphragm
An increase in low-side pressure
The sensing bulb at a lower temperature than the valve body

13. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It would cause the low-side pressure to decrease
The internal overload is opened
50-65

14. 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
The oil pump pressure and the crankcase pressure
An increase of air leakage from ductwork
Clean the condenser coil
A start relay

15. What are the operating pressures of an oil pressure safety switch...
Evaporator and compressor
Technician B
The oil pump pressure and the crankcase pressure
The discharge pressure increases and the amperage increases

16. 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...
An uninsulated suction line and a restricted metering device
The internal overload is opened
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
('Y' and 'C') and ('G' and 'C')

17. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician A is correct
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It keeps a constant superheat in the evaporator
An open internal overload protector

18. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
An acid-core suction line drier
Condenser fans operating during a low ambient condition and a low suction pressure
The external equalizer could be plugged

19. A hard-start kit consists of...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A start capacitor and a solid-state relay
The sensing bulb at a lower temperature than the valve body
The superheat will increase and the low-side pressure will decrease

20. 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 increase of air leakage from ductwork
Technician B
Evaporator and compressor

21. Superheat is found in an air conditioning system in the...
High superheat and low discharge pressure
('Y' and 'C') and ('G' and 'C')
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Evaporator and compressor

22. 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 start capacitor and a solid-state relay
A low refrigerant charge
The system has been overcharged+The system has air trapped in the condenser
Technician B

23. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Both technicians are incorrect
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A sensing bulb improperly connected to the suction line
A missing air filter+improper rotation of the indoor blower+blower too small

24. What is the purpose of an EPR valve...
Low discharge pressure - high suction pressure - and low amp draw
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are incorrect

25. What are three methods for controlling a system's high-side pressure during low ambient conditions...
High superheat and low discharge pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
An increase of air leakage from ductwork
Technician B

26. A restricted air filter in an air conditioning system can be identified by...
Low superheat
Low discharge pressure - high suction pressure - and low amp draw
High suction pressure and low superheat
The sight glass is full of liquid+the sight glass is full of gas

27. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
110-120
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A plugged filter drier

28. 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...
An increase in low-side pressure
It keeps a constant superheat in the evaporator
Low discharge pressure - high suction pressure - and low amp draw
High superheat and low discharge pressure

29. What are the symptoms of a TXV air conditioning system if it has lost its charge...
'G' to 'C'
High superheat and low discharge pressure
The superheat will increase and the low-side pressure will decrease
An increase in low-side pressure

30. 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
Both technicians are correct
An uninsulated suction line and a restricted metering device
The sight glass is full of liquid+the sight glass is full of gas

31. What causes the automatic expansion valve to close...
('Y' and 'C') and ('G' and 'C')
An increase in low-side pressure
An overcharged system
Always have some liquid present in the bulb and diaphragm

32. 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
Both technicians are incorrect
Technician A
Lack of airflow
A dirty condenser - recirculation of condenser air - and a defective condenser fan

33. The internal overload of an air conditioning compressor senses winding temperature and...
An overcharged system
Current in the compressor circuit
The low-side pressure will decrease and the evaporator coil will be partially frosted
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

34. Which of the following will cause excessive discharge pressures on an air conditioning system...
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B
An increase of air leakage from ductwork

35. 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...
Current in the compressor circuit
Current in the compressor circuit
Partially frosted evaporator and high superheat
Condenser fans operating during a low ambient condition and a low suction pressure

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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An overcharged system
A blown fuse
Both technicians are incorrect

37. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A missing air filter+improper rotation of the indoor blower+blower too small
An uninsulated TXV sensing bulb
Technician B

38. A system that uses a thermal electric expansion valve...
20 to 30
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The discharge pressure increases and the amperage increases

39. What are two common symptoms of refrigerant leaks in an air conditioning system...
A vacuum test+oil traces around fittings+soap bubble solution
Partially frosted evaporator and high superheat
An overcharged system
Condenser fans operating during a low ambient condition and a low suction pressure

40. A commercial customer calls on a 90
'G' to 'C'
A start relay
A plugged filter drier
The system has been overcharged+The system has air trapped in the condenser

41. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An uninsulated suction line and a restricted metering device
A low refrigerant charge
The low-side pressure will decrease and the evaporator coil will be partially frosted

42. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated suction line and a restricted metering device
A blown fuse
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Current in the compressor circuit

43. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
110-120
An overcharged system
A defective circuit breaker

44. 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 could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A defective circuit breaker
A missing air filter+improper rotation of the indoor blower+blower too small
Flooding the condenser - cycling condenser fans - and dampering condenser air

45. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

46. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Increases starting torque
Current in the compressor circuit

47. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B
An overcharged system
The external equalizer could be plugged

48. 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
Short cycling and insufficient dehumidification
A defective circuit breaker
A bad thermostat
Low superheat

49. 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
Technician B
It keeps a constant superheat in the evaporator
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An acid-core suction line drier

50. What problem or problems can cause low discharge and suction pressure...
Low voltage and a faulty start relay
An undercharged system+insufficient airflow over the evaporator coil
An acid-core suction line drier
An acid-core suction line drier