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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 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 bad thermostat
Low voltage and a faulty start relay
An acid-core suction line drier
Technician B

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
Increases starting torque
50-65
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

3. The best description of a relay would be...
The oil pump pressure and the crankcase pressure
A defective circuit breaker
Contains a solenoid coil and one or more sets of contacts
Technician B

4. A system that is operating with a clear sight glass shows...
An increase in suction pressure and an increase in discharge pressure
A sensing bulb improperly connected to the suction line
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The sight glass is full of liquid+the sight glass is full of gas

5. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An undercharge and low ambient conditions
It would cause the low-side pressure to decrease
A plugged filter drier
The superheat increases and the subcooling decreases

6. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An open internal overload protector
Technician A is correct
The system has been overcharged+The system has air trapped in the condenser
A missing air filter+improper rotation of the indoor blower+blower too small

7. 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 undercharge and low ambient conditions
An increase in suction pressure and an increase in discharge pressure
High suction pressure and low superheat
The external equalizer could be plugged

8. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Condenser fans operating during a low ambient condition and a low suction pressure
Clean the condenser coil
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

9. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
A start relay
A sensing bulb improperly connected to the suction line
An undercharge and low ambient conditions

10. What are two common symptoms of refrigerant leaks in an air conditioning system...
An increase in suction pressure and an increase in discharge pressure
Partially frosted evaporator and high superheat
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An acid-core suction line drier

11. What are two common symptoms of refrigerant leaks in an air conditioning system...
It would cause the low-side pressure to decrease
An undercharged system+insufficient airflow over the evaporator coil
An overcharged system
Partially frosted evaporator and high superheat

12. Which of the following can cause low superheat in a TXV system...
A bad thermostat
An uninsulated TXV sensing bulb
The system has been overcharged+The system has air trapped in the condenser
Technician B

13. 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
Short cycling and insufficient dehumidification
Low superheat
A low refrigerant charge

14. A system that uses a thermal electric expansion valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Both technicians are incorrect
The superheat increases and the subcooling decreases

15. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
An undercharged system+insufficient airflow over the evaporator coil
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An uninsulated suction line and a restricted metering device
Technician B

16. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Technician B
Increases starting torque
The discharge pressure increases and the amperage increases
Dirty condenser - bent condenser fins - and air recirculating over the condenser

17. 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...
A blown fuse
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It is used to control refrigerant pressure in the compressor crankcase

18. 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 start capacitor and a solid-state relay
Technician B
Clean the condenser coil
It is used to control refrigerant pressure in the compressor crankcase

19. 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
Current in the compressor circuit
Technician B
Evaporator and compressor
A missing air filter+improper rotation of the indoor blower+blower too small

20. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The sight glass is full of liquid+the sight glass is full of gas
Low discharge pressure - high suction pressure - and low amp draw
An increase in suction pressure and an increase in discharge pressure

21. Air filters should be replaced...
Whenever necessary
Rise more than normal
Run with high head and high suction pressure
The internal overload is opened

22. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The sensing bulb at a lower temperature than the valve body
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Bad compressor valve
An increase in low-side pressure

23. What problem or problems can cause low discharge and suction pressure...
A bad thermostat
Evaporator and compressor
The discharge pressure increases and the amperage increases
An undercharged system+insufficient airflow over the evaporator coil

24. 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
110-120
A defective circuit breaker
Technician B
The external equalizer could be plugged

25. A customer calls with an insufficient cooling complaint on a 90
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
The external equalizer could be plugged
Run with high head and high suction pressure

26. What problem or problems can cause low discharge and suction pressure...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An undercharged system+insufficient airflow over the evaporator coil
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An acid-core suction line drier

27. 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
Technician B
Technician A
An open internal overload protector
Increases starting torque

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...
High superheat and low discharge pressure
An open internal overload protector
Both technicians are correct
Technician B

29. A technician arrives on the job and the customer complains that there is no cooling on his rooftop unit. Troubleshooting the system - the technician finds that the compressor is faulty. He notices that there is another faulty compressor laying next t
Broken rings+broken valves+seized bearings
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An open internal overload protector
The sensing bulb at a lower temperature than the valve body

30. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
Both technicians are incorrect
Low discharge pressure - high suction pressure - and low amp draw
Technician A is correct

31. A customer calls with an insufficient cooling complaint on a 90
Technician B
A sensing bulb improperly connected to the suction line
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Current in the compressor circuit

32. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Run with high head and high suction pressure
The external equalizer could be plugged
Clean the condenser coil
A bad thermostat

33. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Low discharge pressure - high suction pressure - and low amp draw
The superheat will increase and the low-side pressure will decrease
A plugged filter drier
An overcharged system

34. A compressor having tight bearings would cause the current value to...
The sight glass is full of liquid+the sight glass is full of gas
Low superheat
Low discharge pressure - high suction pressure - and low amp draw
Rise more than normal

35. A hard-start kit for an air conditioning system...
Both technicians are correct
Increases starting torque
Condenser fans operating during a low ambient condition and a low suction pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

36. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
Run with high head and high suction pressure
Both technicians are correct
Broken rings+broken valves+seized bearings
Technician B

37. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A sensing bulb improperly connected to the suction line
Low discharge pressure - high suction pressure - and low amp draw

38. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The sight glass is full of liquid+the sight glass is full of gas
The oil pump pressure and the crankcase pressure
Bad compressor valve
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

39. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Technician B
High suction pressure and low superheat
Technician B
A restricted metering device

40. 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
('Y' and 'C') and ('G' and 'C')
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small

41. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...

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42. What three things can prevent an air conditioning system from releasing heat at the proper rate...
An open internal overload protector
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Whenever necessary
Technician B

43. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Technician A is correct
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Bad compressor valve

44. What is the purpose of an EPR valve...
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
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

45. 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...
It keeps a constant superheat in the evaporator
The discharge pressure increases and the amperage increases
High superheat and low discharge pressure
Lack of airflow

46. What type of problems can be caused by an oversized air conditioning system...
Technician B
The superheat will increase and the low-side pressure will decrease
Short cycling and insufficient dehumidification
Low voltage and a faulty start relay

47. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
The external equalizer could be plugged
Technician A
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

48. A compressor having tight bearings would cause the current value to...
An open internal overload protector
The discharge pressure increases and the amperage increases
Contains a solenoid coil and one or more sets of contacts
Rise more than normal

49. What are three methods for controlling a system's high-side pressure during low ambient conditions...
The external equalizer could be plugged
An increase in suction pressure and an increase in discharge pressure
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air

50. The internal overload of an air conditioning compressor senses winding temperature and...
Both technicians are incorrect
Current in the compressor circuit
('Y' and 'C') and ('G' and 'C')
A restricted metering device