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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. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
Broken rings+broken valves+seized bearings
Both technicians are correct
Rise more than normal

2. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The superheat increases and the subcooling decreases
A low refrigerant charge
The low-side pressure will decrease and the evaporator coil will be partially frosted
An increase in suction pressure and an increase in discharge pressure

3. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A low refrigerant charge
An uninsulated suction line and a restricted metering device
Low superheat
Run with high head and high suction pressure

4. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
50-65
High superheat and low discharge pressure
Technician B
High suction pressure and low superheat

5. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The external equalizer could be plugged

6. A hard-start kit consists of...
Contains a solenoid coil and one or more sets of contacts
A start capacitor and a solid-state relay
The external equalizer could be plugged
Technician A

7. Which of the following can cause low superheat in a TXV system...
Bad compressor valve
An uninsulated TXV sensing bulb
A defective circuit breaker
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

8. 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...
A defective circuit breaker
The external equalizer could be plugged
Condenser fans operating during a low ambient condition and a low suction pressure
High superheat and low discharge pressure

9. 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
Both technicians are incorrect
Short cycling and insufficient dehumidification
Technician B
An increase in low-side pressure

10. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Clean the condenser coil
Technician B
A low refrigerant charge
A missing air filter+improper rotation of the indoor blower+blower too small

11. A restricted air filter in an air conditioning system can be identified by...
It would cause the low-side pressure to decrease
An undercharge and low ambient conditions
Low superheat
('Y' and 'C') and ('G' and 'C')

12. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
50-65
3 psig
A bad thermostat

13. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
20 to 30
110-120
Current in the compressor circuit
Low superheat

14. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Lack of airflow
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The internal overload is opened

15. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
('Y' and 'C') and ('G' and 'C')
The oil pump pressure and the crankcase pressure
An increase in low-side pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

16. 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 fans operating during a low ambient condition and a low suction pressure
A defective circuit breaker
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

17. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
An open internal overload protector
20 to 30
High superheat and low discharge pressure

18. The temperature range of the suction line from an air conditioning system should be...
50-65
High suction pressure and low superheat
Flooding the condenser - cycling condenser fans - and dampering condenser air
Always have some liquid present in the bulb and diaphragm

19. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An overcharged system
Flooding the condenser - cycling condenser fans - and dampering condenser air
A plugged filter drier

20. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
'G' to 'C'
A start relay
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

21. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
50-65
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

22. Which of the following is a common cause of an excessively low superheat on a TXV system...
The discharge pressure increases and the amperage increases
3 psig
It is used to control refrigerant pressure in the compressor crankcase
A sensing bulb improperly connected to the suction line

23. 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 overcharged system
An open internal overload protector
Both technicians are correct
Whenever necessary

24. 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
'G' to 'C'
An increase in suction pressure and an increase in discharge pressure
An increase of air leakage from ductwork
Technician B

25. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
50-65
Whenever necessary

26. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
An increase of air leakage from ductwork
Flooding the condenser - cycling condenser fans - and dampering condenser air
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Broken rings+broken valves+seized bearings

27. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Both technicians are incorrect

28. Why is it unsafe to operate an air conditioning system with a low charge...
It would cause the low-side pressure to decrease
The superheat increases and the subcooling decreases
50-65
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

29. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Technician A
Both technicians are correct
An increase in low-side pressure
It would cause the low-side pressure to decrease

30. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
3 psig
The superheat will increase and the low-side pressure will decrease
An open internal overload protector

31. What type of problems can be caused by an oversized air conditioning system...
A start capacitor and a solid-state relay
A vacuum test+oil traces around fittings+soap bubble solution
Short cycling and insufficient dehumidification
Clean the condenser coil

32. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Condenser fans operating during a low ambient condition and a low suction pressure
20 to 30
Low discharge pressure - high suction pressure - and low amp draw

33. Air filters should be replaced...
Broken rings+broken valves+seized bearings
Whenever necessary
A plugged filter drier
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

34. What is the purpose of a CPR valve...
A blown fuse
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Contains a solenoid coil and one or more sets of contacts
It is used to control refrigerant pressure in the compressor crankcase

35. A system that is operating with a clear sight glass shows...
Bad compressor valve
An uninsulated TXV sensing bulb
The sight glass is full of liquid+the sight glass is full of gas
An undercharged system+insufficient airflow over the evaporator coil

36. The internal overload of an air conditioning compressor senses winding temperature and...
The discharge pressure increases and the amperage increases
Current in the compressor circuit
Technician B
An overcharged system

37. 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
Both technicians are incorrect
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The external equalizer could be plugged

38. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Technician A is correct
Flooding the condenser - cycling condenser fans - and dampering condenser air
An undercharge and low ambient conditions
Contains a solenoid coil and one or more sets of contacts

39. What is the purpose of the TXV...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An increase in suction pressure and an increase in discharge pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
It keeps a constant superheat in the evaporator

40. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
Both technicians are incorrect
An increase in suction pressure and an increase in discharge pressure
A restricted metering device

41. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
The superheat will increase and the low-side pressure will decrease
High superheat and low discharge pressure
Rise more than normal

42. Superheat is found in an air conditioning system in the...
Rise more than normal
An open internal overload protector
Evaporator and compressor
Both technicians are correct

43. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
Technician B
'G' to 'C'
A missing air filter+improper rotation of the indoor blower+blower too small

44. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Low superheat
An undercharge and low ambient conditions
A start relay
An uninsulated TXV sensing bulb

45. What are two problems that can cause an air conditioning system to have an excessively high superheat...
110-120
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An uninsulated suction line and a restricted metering device
The discharge pressure increases and the amperage increases

46. 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...
Both technicians are correct
Broken rings+broken valves+seized bearings
A low refrigerant charge
High superheat and low discharge pressure

47. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An undercharged system+insufficient airflow over the evaporator coil
An uninsulated suction line and a restricted metering device

48. Insufficient airflow can be caused by...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
An increase of air leakage from ductwork
Low superheat

49. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Low discharge pressure - high suction pressure - and low amp draw
3 psig
It keeps a constant superheat in the evaporator
It would cause the low-side pressure to decrease

50. Why is it unsafe to operate an air conditioning system with a low charge...
Partially frosted evaporator and high superheat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
An increase of air leakage from ductwork