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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 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
An overcharged system
Both technicians are incorrect

2. 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
Always have some liquid present in the bulb and diaphragm
Run with high head and high suction pressure
Technician A is correct

3. The temperature range of the suction line from an air conditioning system should be...
Technician A is correct
It would cause the low-side pressure to decrease
50-65
The low-side pressure will decrease and the evaporator coil will be partially frosted

4. What problem or problems can cause low discharge and suction pressure...
An increase of air leakage from ductwork
The superheat increases and the subcooling decreases
Rise more than normal
An undercharged system+insufficient airflow over the evaporator coil

5. A liquid-charged TXV bulb will...
Both technicians are incorrect
An increase in low-side pressure
50-65
Always have some liquid present in the bulb and diaphragm

6. 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
A defective circuit breaker
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The system has been overcharged+The system has air trapped in the condenser
Broken rings+broken valves+seized bearings

7. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Evaporator and compressor
An undercharge and low ambient conditions
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A defective circuit breaker

8. 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
The system has been overcharged+The system has air trapped in the condenser
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
High superheat and low discharge pressure

9. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Low voltage and a faulty start relay
An increase in suction pressure and an increase in discharge pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

10. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A start relay
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Lack of airflow
An overcharged system

11. Which of the following could be the cause for a system's discharge and suction pressure being low...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Short cycling and insufficient dehumidification
A bad thermostat
A restricted metering device

12. 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
A plugged filter drier
An open internal overload protector
Current in the compressor circuit
An undercharge and low ambient conditions

13. 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...
Technician B
Low discharge pressure - high suction pressure - and low amp draw
High superheat and low discharge pressure
Technician B

14. What is the purpose of the TXV...
An uninsulated suction line and a restricted metering device
'G' to 'C'
It keeps a constant superheat in the evaporator
Always have some liquid present in the bulb and diaphragm

15. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
It is used to control refrigerant pressure in the compressor crankcase
Current in the compressor circuit
The discharge pressure increases and the amperage increases
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

16. 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
Broken rings+broken valves+seized bearings
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The sensing bulb at a lower temperature than the valve body

17. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
The oil pump pressure and the crankcase pressure
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
The external equalizer could be plugged

18. 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 bad thermostat
Technician B
A start capacitor and a solid-state relay
('Y' and 'C') and ('G' and 'C')

19. 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
A restricted metering device
The sight glass is full of liquid+the sight glass is full of gas
Whenever necessary
Broken rings+broken valves+seized bearings

20. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The oil pump pressure and the crankcase pressure
A missing air filter+improper rotation of the indoor blower+blower too small
Flooding the condenser - cycling condenser fans - and dampering condenser air

21. 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
Technician B
A start relay
Bad compressor valve
Low superheat

22. What are three methods for controlling a system's high-side pressure during low ambient conditions...
An acid-core suction line drier
Low superheat
Flooding the condenser - cycling condenser fans - and dampering condenser air
A vacuum test+oil traces around fittings+soap bubble solution

23. Why is it unsafe to operate an air conditioning system with a low charge...
Contains a solenoid coil and one or more sets of contacts
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase of air leakage from ductwork
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

24. Superheat is found in an air conditioning system in the...
Evaporator and compressor
Both technicians are incorrect
An acid-core suction line drier
An uninsulated suction line and a restricted metering device

25. A hard-start kit for an air conditioning system...
Increases starting torque
A dirty condenser - recirculation of condenser air - and a defective condenser fan
110-120
Run with high head and high suction pressure

26. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Low voltage and a faulty start relay
Both technicians are incorrect
The superheat increases and the subcooling decreases
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

27. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
The system has been overcharged+The system has air trapped in the condenser
An uninsulated suction line and a restricted metering device
Whenever necessary
It would cause the low-side pressure to decrease

28. The best description of a relay would be...
A restricted metering device
Contains a solenoid coil and one or more sets of contacts
A restricted metering device
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

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...
Always have some liquid present in the bulb and diaphragm
Lack of airflow
Low discharge pressure - high suction pressure - and low amp draw
Condenser fans operating during a low ambient condition and a low suction pressure

30. Why is it unsafe to operate an air conditioning system with a low charge...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
High suction pressure and low superheat
An increase of air leakage from ductwork
20 to 30

31. 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 restricted metering device
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
Broken rings+broken valves+seized bearings

32. A system that is operating with a clear sight glass shows...
Partially frosted evaporator and high superheat
The sight glass is full of liquid+the sight glass is full of gas
The system has been overcharged+The system has air trapped in the condenser
Whenever necessary

33. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
An increase of air leakage from ductwork
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Run with high head and high suction pressure
Both technicians are correct

34. 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...
Broken rings+broken valves+seized bearings
An increase in low-side pressure
Condenser fans operating during a low ambient condition and a low suction pressure
An increase in suction pressure and an increase in discharge pressure

35. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
A vacuum test+oil traces around fittings+soap bubble solution
3 psig
Run with high head and high suction pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted

36. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A start capacitor and a solid-state relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Run with high head and high suction pressure
High suction pressure and low superheat

37. 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 dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An open internal overload protector
A bad thermostat
The oil pump pressure and the crankcase pressure

38. What are two common symptoms of refrigerant leaks in an air conditioning system...
It keeps a constant superheat in the evaporator
Partially frosted evaporator and high superheat
The superheat increases and the subcooling decreases
Low voltage and a faulty start relay

39. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
110-120
Broken rings+broken valves+seized bearings
Bad compressor valve
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

40. 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...
Technician B
Increases starting torque
The internal overload is opened
The oil pump pressure and the crankcase pressure

41. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A low refrigerant charge
High superheat and low discharge pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan

42. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Increases starting torque

43. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A bad thermostat
Flooding the condenser - cycling condenser fans - and dampering condenser air
20 to 30
Technician B

44. 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 plugged filter drier
A blown fuse
An open internal overload protector
20 to 30

45. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
20 to 30
An open internal overload protector
An open internal overload protector

46. 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
50-65
Technician A is correct
The superheat increases and the subcooling decreases
The oil pump pressure and the crankcase pressure

47. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
Technician A is correct
It keeps a constant superheat in the evaporator
A dirty condenser - recirculation of condenser air - and a defective condenser fan

48. Which of the following can cause excessive subcooling...
The superheat will increase and the low-side pressure will decrease
Broken rings+broken valves+seized bearings
An overcharged system
20 to 30

49. Which of the following is a common cause of an excessively low superheat on a TXV system...
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 internal overload is opened
('Y' and 'C') and ('G' and 'C')

50. A restricted air filter in an air conditioning system can be identified by...
Low superheat
Run with high head and high suction pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
'G' to 'C'