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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
An increase in low-side pressure
Broken rings+broken valves+seized bearings
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B

2. What are the symptoms of an air conditioning system that has a low charge...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Bad compressor valve
Technician B
Broken rings+broken valves+seized bearings

3. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A blown fuse
'G' to 'C'

4. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An overcharged system
The superheat increases and the subcooling decreases
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

5. 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 low-side pressure
High superheat and low discharge pressure
An increase in suction pressure and an increase in discharge pressure

6. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
An increase in suction pressure and an increase in discharge pressure
A defective circuit breaker
3 psig
Technician B

7. 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...
Low superheat
High superheat and low discharge pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

8. A system that is operating with a clear sight glass shows...
Bad compressor valve
50-65
Clean the condenser coil
The sight glass is full of liquid+the sight glass is full of gas

9. Air filters should be replaced...
High suction pressure and low superheat
An overcharged system
An acid-core suction line drier
Whenever necessary

10. What causes the automatic expansion valve to close...
An increase in low-side pressure
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
Technician B

11. Which of the following can cause excessive subcooling...
Clean the condenser coil
Run with high head and high suction pressure
An increase of air leakage from ductwork
An overcharged system

12. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
The sensing bulb at a lower temperature than the valve body
Run with high head and high suction pressure
Increases starting torque
110-120

13. What are two problems that can cause an air conditioning system to have an excessively high superheat...
20 to 30
Evaporator and compressor
Whenever necessary
An uninsulated suction line and a restricted metering device

14. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Low superheat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Lack of airflow
An increase in low-side pressure

15. 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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The oil pump pressure and the crankcase pressure

16. A hard-start kit consists of...
An acid-core suction line drier
A start capacitor and a solid-state relay
Evaporator and compressor
An increase in suction pressure and an increase in discharge pressure

17. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
An increase in low-side pressure
'G' to 'C'
The low-side pressure will decrease and the evaporator coil will be partially frosted

18. A liquid-charged TXV bulb will...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Always have some liquid present in the bulb and diaphragm
Run with high head and high suction pressure
Short cycling and insufficient dehumidification

19. 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
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
A bad thermostat
An open internal overload protector

20. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
Evaporator and compressor
110-120
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

21. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An overcharged system
Technician B
The superheat increases and the subcooling decreases
The oil pump pressure and the crankcase pressure

22. Which of the following will cause excessive discharge pressures on an air conditioning system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
('Y' and 'C') and ('G' and 'C')
An increase in low-side pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air

23. 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 A
Technician A is correct
Both technicians are incorrect
20 to 30

24. 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
An increase of air leakage from ductwork
A defective circuit breaker
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

25. 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 is used to control refrigerant pressure in the compressor crankcase
Technician B
Technician A is correct
Bad compressor valve

26. A customer calls with an insufficient cooling complaint on a 90
Partially frosted evaporator and high superheat
The discharge pressure increases and the amperage increases
Technician B
A blown fuse

27. 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
Technician A is correct
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
3 psig

28. What are the operating pressures of an oil pressure safety switch...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The oil pump pressure and the crankcase pressure
Both technicians are correct
Both technicians are correct

29. 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 uninsulated TXV sensing bulb
The external equalizer could be plugged
Run with high head and high suction pressure
Condenser fans operating during a low ambient condition and a low suction pressure

30. Which of the following can cause low superheat in a TXV system...
Always have some liquid present in the bulb and diaphragm
An uninsulated TXV sensing bulb
Broken rings+broken valves+seized bearings
The external equalizer could be plugged

31. 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
It would cause the low-side pressure to decrease
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

32. What type of problems can be caused by an oversized air conditioning system...
Always have some liquid present in the bulb and diaphragm
A dirty condenser - recirculation of condenser air - and a defective condenser fan
It keeps a constant superheat in the evaporator
Short cycling and insufficient dehumidification

33. Why is it unsafe to operate an air conditioning system with a low charge...
3 psig
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Contains a solenoid coil and one or more sets of contacts
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

34. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Both technicians are correct
Technician B
An increase in suction pressure and an increase in discharge pressure

35. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Evaporator and compressor
Dirty condenser - bent condenser fins - and air recirculating over the condenser
3 psig
High suction pressure and low superheat

36. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Contains a solenoid coil and one or more sets of contacts
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Low discharge pressure - high suction pressure - and low amp draw
The superheat will increase and the low-side pressure will decrease

37. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
'G' to 'C'
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A start capacitor and a solid-state relay

38. The internal overload of an air conditioning compressor senses winding temperature and...
The oil pump pressure and the crankcase pressure
Current in the compressor circuit
An overcharged system
Technician A

39. 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 low refrigerant charge
Technician B
Contains a solenoid coil and one or more sets of contacts
Broken rings+broken valves+seized bearings

40. 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
It is used to control refrigerant pressure in the compressor crankcase
Technician B
The discharge pressure increases and the amperage increases

41. 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 increase in suction pressure and an increase in discharge pressure
Broken rings+broken valves+seized bearings
The superheat increases and the subcooling decreases
Technician A is correct

42. A restricted air filter in an air conditioning system can be identified by...
The discharge pressure increases and the amperage increases
Low superheat
Short cycling and insufficient dehumidification
The system has been overcharged+The system has air trapped in the condenser

43. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A plugged filter drier
High suction pressure and low superheat
An overcharged system
An undercharged system+insufficient airflow over the evaporator coil

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 was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The superheat will increase and the low-side pressure will decrease
A defective circuit breaker

45. A customer calls with an insufficient cooling complaint on a 90
Current in the compressor circuit
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

46. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
An increase in suction pressure and an increase in discharge pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Low discharge pressure - high suction pressure - and low amp draw
Technician A

47. Which of the following could be the cause for a system's discharge and suction pressure being low...
3 psig
A restricted metering device
Current in the compressor circuit
The discharge pressure increases and the amperage increases

48. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
It would cause the low-side pressure to decrease

49. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A blown fuse
A missing air filter+improper rotation of the indoor blower+blower too small

50. The best description of a relay would be...
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
Contains a solenoid coil and one or more sets of contacts
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil