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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. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
It keeps a constant superheat in the evaporator
The discharge pressure increases and the amperage increases
Always have some liquid present in the bulb and diaphragm
Dirty condenser - bent condenser fins - and air recirculating over the condenser

2. The internal overload of an air conditioning compressor senses winding temperature and...
A start capacitor and a solid-state relay
Run with high head and high suction pressure
3 psig
Current in the compressor circuit

3. Insufficient airflow can be caused by...
The sensing bulb at a lower temperature than the valve body
An increase of air leakage from ductwork
The low-side pressure will decrease and the evaporator coil will be partially frosted
A start capacitor and a solid-state relay

4. Which of the following is a possible cause for a compressor to overheat...
It keeps a constant superheat in the evaporator
A low refrigerant charge
3 psig
50-65

5. A hard-start kit for an air conditioning system...
Increases starting torque
An increase in low-side pressure
The superheat increases and the subcooling decreases
A blown fuse

6. A restricted air filter in an air conditioning system can be identified by...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
110-120
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Low superheat

7. Why is it unsafe to operate an air conditioning system with a low charge...
An acid-core suction line drier
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
It is used to control refrigerant pressure in the compressor crankcase
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

8. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Both technicians are correct
It would cause the low-side pressure to decrease
A sensing bulb improperly connected to the suction line
The low-side pressure will decrease and the evaporator coil will be partially frosted

9. Which of the following is a possible cause for a compressor to overheat...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A restricted metering device
The discharge pressure increases and the amperage increases
A low refrigerant charge

10. What problem or problems can cause low discharge and suction pressure...
Run with high head and high suction pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An undercharged system+insufficient airflow over the evaporator coil
Technician A is correct

11. When using a vapor-charged TXV bulb - it is necessary to have...
The oil pump pressure and the crankcase pressure
It is used to control refrigerant pressure in the compressor crankcase
The sensing bulb at a lower temperature than the valve body
An increase of air leakage from ductwork

12. 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
Low superheat
Low voltage and a faulty start relay
Contains a solenoid coil and one or more sets of contacts

13. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Both technicians are incorrect
Current in the compressor circuit
Clean the condenser coil

14. 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
Always have some liquid present in the bulb and diaphragm
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician A is correct

15. What is the purpose of an EPR valve...
A low refrigerant charge
A defective circuit breaker
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system has been overcharged+The system has air trapped in the condenser

16. 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
Always have some liquid present in the bulb and diaphragm
Clean the condenser coil
The oil pump pressure and the crankcase pressure
Technician B

17. What is the purpose of a CPR valve...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It is used to control refrigerant pressure in the compressor crankcase
It keeps a constant superheat in the evaporator
The discharge pressure increases and the amperage increases

18. 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
A blown fuse
50-65
Both technicians are incorrect

19. The temperature range of the suction line from an air conditioning system should be...
A defective circuit breaker
An overcharged system
Run with high head and high suction pressure
50-65

20. What problem can cause an increase of discharge pressure and an increase of suction pressure...
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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An overcharged system

21. 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 blown fuse
An increase of air leakage from ductwork
A dirty condenser - recirculation of condenser air - and a defective condenser fan

22. 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
Lack of airflow
Clean the condenser coil
Technician B
An acid-core suction line drier

23. What are two common symptoms of refrigerant leaks in an air conditioning system...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Low discharge pressure - high suction pressure - and low amp draw
Short cycling and insufficient dehumidification
Partially frosted evaporator and high superheat

24. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A start relay
It would cause the low-side pressure to decrease
Technician B

25. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Broken rings+broken valves+seized bearings
Short cycling and insufficient dehumidification

26. When troubleshooting a split-system air conditioner - it is found that the compressor motor is humming but not starting. Technician A says that it could be an open internal overload protector. Technician B says that it could be a blown fuse. Which te
Technician B
Always have some liquid present in the bulb and diaphragm
Both technicians are incorrect
The sight glass is full of liquid+the sight glass is full of gas

27. 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
The external equalizer could be plugged
The internal overload is opened
A restricted metering device
Technician B

28. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
An uninsulated TXV sensing bulb
High suction pressure and low superheat

29. 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
The sensing bulb at a lower temperature than the valve body
It would cause the low-side pressure to decrease
A sensing bulb improperly connected to the suction line

30. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Always have some liquid present in the bulb and diaphragm
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

31. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
Bad compressor valve
The system has been overcharged+The system has air trapped in the condenser
Whenever necessary

32. Which of the following is a common cause of an excessively low superheat on a TXV system...
Low voltage and a faulty start relay
Run with high head and high suction pressure
A sensing bulb improperly connected to the suction line
High suction pressure and low superheat

33. 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 blown fuse
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A defective circuit breaker
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

34. A hard-start kit for an 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
Increases starting torque
A start capacitor and a solid-state relay

35. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Always have some liquid present in the bulb and diaphragm
Contains a solenoid coil and one or more sets of contacts
A blown fuse
The superheat increases and the subcooling decreases

36. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
It would cause the low-side pressure to decrease
Bad compressor valve
Low voltage and a faulty start relay

37. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
A missing air filter+improper rotation of the indoor blower+blower too small
Low discharge pressure - high suction pressure - and low amp draw
The sensing bulb at a lower temperature than the valve body
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

38. 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 bad thermostat
A restricted metering device
Technician B
An undercharged system+insufficient airflow over the evaporator coil

39. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Technician A
An uninsulated suction line and a restricted metering device
An acid-core suction line drier
Both technicians are correct

40. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Technician A
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
The superheat increases and the subcooling decreases

41. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Low superheat
An increase in suction pressure and an increase in discharge pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
High suction pressure and low superheat

42. 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
The external equalizer could be plugged
An acid-core suction line drier
An increase of air leakage from ductwork
A start capacitor and a solid-state relay

43. 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 bad thermostat
3 psig
Lack of airflow

44. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Rise more than normal
The sensing bulb at a lower temperature than the valve body
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
3 psig

45. What type of problems can be caused by an oversized air conditioning system...
An undercharge and low ambient conditions
Short cycling and insufficient dehumidification
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Both technicians are correct

46. 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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47. A compressor having tight bearings would cause the current value to...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Current in the compressor circuit
20 to 30
Rise more than normal

48. What causes the automatic expansion valve to close...
Low discharge pressure - high suction pressure - and low amp draw
A start capacitor and a solid-state relay
An increase in low-side pressure
Clean the condenser coil

49. 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
Technician A is correct
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A restricted metering device

50. 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
Condenser fans operating during a low ambient condition and a low suction pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician A
Low superheat