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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 are two common symptoms of refrigerant leaks in an air conditioning system...
Condenser fans operating during a low ambient condition and a low suction pressure
Rise more than normal
Technician B
Partially frosted evaporator and high superheat

2. 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
Contains a solenoid coil and one or more sets of contacts
It is used to control refrigerant pressure in the compressor crankcase
Flooding the condenser - cycling condenser fans - and dampering condenser air

3. What component is most often the cause of a start capacitor failure...
A start relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An undercharged system+insufficient airflow over the evaporator coil
An open internal overload protector

4. What type of problems can be caused by an oversized air conditioning system...
50-65
Short cycling and insufficient dehumidification
Condenser fans operating during a low ambient condition and a low suction pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

5. 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
The sensing bulb at a lower temperature than the valve body
An uninsulated TXV sensing bulb
An increase of air leakage from ductwork
Technician A is correct

6. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
20 to 30
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Low discharge pressure - high suction pressure - and low amp draw
A restricted metering device

7. A hard-start kit consists of...
An uninsulated suction line and a restricted metering device
'G' to 'C'
A start capacitor and a solid-state relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

8. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A blown fuse
Short cycling and insufficient dehumidification

9. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Technician B
The discharge pressure increases and the amperage increases
Flooding the condenser - cycling condenser fans - and dampering condenser air
Always have some liquid present in the bulb and diaphragm

10. What is the purpose of the TXV...
An open internal overload protector
It keeps a constant superheat in the evaporator
Short cycling and insufficient dehumidification
Technician B

11. A system that uses a thermal electric expansion valve...
Both technicians are incorrect
The system has been overcharged+The system has air trapped in the condenser
A defective circuit breaker
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

12. Which of the following is a possible cause for a compressor to overheat...
The sensing bulb at a lower temperature than the valve body
A low refrigerant charge
The low-side pressure will decrease and the evaporator coil will be partially frosted
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

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...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Current in the compressor circuit
High superheat and low discharge pressure
Technician B

14. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Whenever necessary
Both technicians are incorrect
The superheat will increase and the low-side pressure will decrease
Short cycling and insufficient dehumidification

15. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Lack of airflow
A bad thermostat
Evaporator and compressor
High suction pressure and low superheat

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
Technician B
An uninsulated suction line and a restricted metering device
A defective circuit breaker
Low superheat

17. 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
Evaporator and compressor
High superheat and low discharge pressure
Low voltage and a faulty start relay

18. 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
Both technicians are correct
An acid-core suction line drier
Bad compressor valve
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

19. What causes the automatic expansion valve to close...
Lack of airflow
Condenser fans operating during a low ambient condition and a low suction pressure
An increase in low-side pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser

20. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Low voltage and a faulty start relay
Low discharge pressure - high suction pressure - and low amp draw
50-65
Always have some liquid present in the bulb and diaphragm

21. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
An undercharged system+insufficient airflow over the evaporator coil
It would cause the low-side pressure to decrease
Technician B
Technician B

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
The oil pump pressure and the crankcase pressure
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A low refrigerant charge

23. Which of the following can cause low superheat in a TXV system...
An undercharge and low ambient conditions
Low voltage and a faulty start relay
Short cycling and insufficient dehumidification
An uninsulated TXV sensing bulb

24. Which of the following is a common cause of an excessively low superheat on a TXV system...
('Y' and 'C') and ('G' and 'C')
An undercharge and low ambient conditions
The system has been overcharged+The system has air trapped in the condenser
A sensing bulb improperly connected to the suction line

25. 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 relay
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
110-120
Technician B

26. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Always have some liquid present in the bulb and diaphragm
Always have some liquid present in the bulb and diaphragm
An open internal overload protector
A dirty condenser - recirculation of condenser air - and a defective condenser fan

27. 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
An acid-core suction line drier
Technician A
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

28. Air filters should be replaced...
Whenever necessary
The superheat will increase and the low-side pressure will decrease
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The low-side pressure will decrease and the evaporator coil will be partially frosted

29. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
Run with high head and high suction pressure
Evaporator and compressor
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

30. 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
An uninsulated suction line and a restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A restricted metering device

31. Which of the following can cause excessive subcooling...
The superheat increases and the subcooling decreases
Partially frosted evaporator and high superheat
An overcharged system
Clean the condenser coil

32. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Short cycling and insufficient dehumidification
The superheat will increase and the low-side pressure will decrease
Low discharge pressure - high suction pressure - and low amp draw
An overcharged system

33. What is the common cause of a compressor burnout...
An open internal overload protector
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Whenever necessary
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

34. 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
Current in the compressor circuit
An acid-core suction line drier
Both technicians are incorrect
Clean the condenser coil

35. A liquid-charged TXV bulb will...
An open internal overload protector
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Always have some liquid present in the bulb and diaphragm

36. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The superheat will increase and the low-side pressure will decrease
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The sight glass is full of liquid+the sight glass is full of gas

37. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Technician B
The system has been overcharged+The system has air trapped in the condenser
Condenser fans operating during a low ambient condition and a low suction pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

38. Insufficient airflow can be caused by...
Rise more than normal
It keeps a constant superheat in the evaporator
A blown fuse
An increase of air leakage from ductwork

39. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
The external equalizer could be plugged
Technician B
110-120

40. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
A bad thermostat
An undercharge and low ambient conditions
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It is used to control refrigerant pressure in the compressor crankcase

41. 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
Rise more than normal
Run with high head and high suction pressure
Technician A
A low refrigerant charge

42. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
The superheat will increase and the low-side pressure will decrease
An undercharge and low ambient conditions
Low superheat

43. 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
Technician B
An overcharged system
The sight glass is full of liquid+the sight glass is full of gas

44. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The sight glass is full of liquid+the sight glass is full of gas

45. What is the purpose of a CPR valve...
A vacuum test+oil traces around fittings+soap bubble solution
Increases starting torque
It is used to control refrigerant pressure in the compressor crankcase
A vacuum test+oil traces around fittings+soap bubble solution

46. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
3 psig
An uninsulated suction line and a restricted metering device

47. A compressor having tight bearings would cause the current value to...
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
Rise more than normal
An overcharged system

48. 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
A low refrigerant charge
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A blown fuse

49. What is the purpose of a CPR valve...
20 to 30
('Y' and 'C') and ('G' and 'C')
It is used to control refrigerant pressure in the compressor crankcase
Low superheat

50. What are the operating pressures of an oil pressure safety switch...
Evaporator and compressor
The oil pump pressure and the crankcase pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Current in the compressor circuit