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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. Which of the following is a common cause of an excessively low superheat on a TXV system...
A plugged filter drier
A sensing bulb improperly connected to the suction line
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
'G' to 'C'

2. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
Technician B
The internal overload is opened
Technician B

3. Air filters should be replaced...
Evaporator and compressor
Whenever necessary
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

4. 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
Evaporator and compressor
The system has been overcharged+The system has air trapped in the condenser
Broken rings+broken valves+seized bearings

5. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
The oil pump pressure and the crankcase pressure
50-65
The superheat increases and the subcooling decreases
Bad compressor valve

6. What three things can prevent an air conditioning system from releasing heat at the proper rate...
It would cause the low-side pressure to decrease
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Evaporator and compressor
A dirty condenser - recirculation of condenser air - and a defective condenser fan

7. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An acid-core suction line drier
Run with high head and high suction pressure
Technician A

8. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
Clean the condenser coil
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure
It is used to control refrigerant pressure in the compressor crankcase

9. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
An increase of air leakage from ductwork
Both technicians are correct
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

10. What are the symptoms of an air conditioning system that has a low charge...
50-65
An increase of air leakage from ductwork
The low-side pressure will decrease and the evaporator coil will be partially frosted
Both technicians are correct

11. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
Short cycling and insufficient dehumidification
110-120
Technician B

12. 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
Low voltage and a faulty start relay
Clean the condenser coil
An open internal overload protector
Technician B

13. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
An increase of air leakage from ductwork
Partially frosted evaporator and high superheat
Technician B
20 to 30

14. 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
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A bad thermostat
('Y' and 'C') and ('G' and 'C')

15. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A bad thermostat
It would cause the low-side pressure to decrease
An undercharge and low ambient conditions
110-120

16. 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
Lack of airflow
Technician A
Both technicians are correct
A blown fuse

17. 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...
The discharge pressure increases and the amperage increases
Short cycling and insufficient dehumidification
Clean the condenser coil
A blown fuse

18. 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
It would cause the low-side pressure to decrease
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
Broken rings+broken valves+seized bearings

19. A hard-start kit for an air conditioning system...
Broken rings+broken valves+seized bearings
A defective circuit breaker
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Increases starting torque

20. Which of the following can cause excessive subcooling...
An uninsulated suction line and a restricted metering device
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An overcharged system

21. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
20 to 30
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure
The superheat will increase and the low-side pressure will decrease

22. A customer calls with an insufficient cooling complaint on a 90
Technician B
Short cycling and insufficient dehumidification
Current in the compressor circuit
The superheat will increase and the low-side pressure will decrease

23. 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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24. What component is most often the cause of a start capacitor failure...
A missing air filter+improper rotation of the indoor blower+blower too small
A start relay
The sight glass is full of liquid+the sight glass is full of gas
The superheat will increase and the low-side pressure will decrease

25. 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
The discharge pressure increases and the amperage increases
An uninsulated TXV sensing bulb
Technician B
Partially frosted evaporator and high superheat

26. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A bad thermostat
An increase of air leakage from ductwork
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

27. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Run with high head and high suction pressure
Current in the compressor circuit
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

28. Air filters should be replaced...
Rise more than normal
Whenever necessary
Both technicians are correct
A missing air filter+improper rotation of the indoor blower+blower too small

29. What is the purpose of the TXV...
A vacuum test+oil traces around fittings+soap bubble solution
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It would cause the low-side pressure to decrease
It keeps a constant superheat in the evaporator

30. Which of the following is a possible cause for a compressor to overheat...
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
A low refrigerant charge
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

31. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Partially frosted evaporator and high superheat
Lack of airflow
An increase in suction pressure and an increase in discharge pressure

32. A hard-start kit for an air conditioning system...
Lack of airflow
Increases starting torque
A start relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

33. 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
The internal overload is opened
Broken rings+broken valves+seized bearings
20 to 30

34. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The low-side pressure will decrease and the evaporator coil will be partially frosted
3 psig

35. A liquid-charged TXV bulb will...
20 to 30
Always have some liquid present in the bulb and diaphragm
Broken rings+broken valves+seized bearings
The system has been overcharged+The system has air trapped in the condenser

36. 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
Bad compressor valve
('Y' and 'C') and ('G' and 'C')
The internal overload is opened
Technician A

37. A restricted air filter in an air conditioning system can be identified by...
Low discharge pressure - high suction pressure - and low amp draw
Low superheat
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An acid-core suction line drier

38. Insufficient airflow can be caused by...
Increases starting torque
Current in the compressor circuit
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An increase of air leakage from ductwork

39. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A restricted metering device
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An increase in suction pressure and an increase in discharge pressure
The superheat will increase and the low-side pressure will decrease

40. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
The sight glass is full of liquid+the sight glass is full of gas
Partially frosted evaporator and high superheat
A plugged filter drier
An overcharged system

41. What problem or problems can cause low discharge and suction pressure...
Partially frosted evaporator and high superheat
Current in the compressor circuit
Flooding the condenser - cycling condenser fans - and dampering condenser air
An undercharged system+insufficient airflow over the evaporator coil

42. Which of the following can cause low superheat in a TXV system...
High superheat and low discharge pressure
An uninsulated TXV sensing bulb
It keeps a constant superheat in the evaporator
Partially frosted evaporator and high superheat

43. 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
Both technicians are incorrect
A restricted metering device
Broken rings+broken valves+seized bearings
A low refrigerant charge

44. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Technician B
An open internal overload protector
The superheat increases and the subcooling decreases
Technician B

45. A compressor having tight bearings would cause the current value to...
Rise more than normal
Partially frosted evaporator and high superheat
The sight glass is full of liquid+the sight glass is full of gas
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

46. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
Clean the condenser coil
It is used to control refrigerant pressure in the compressor crankcase
20 to 30

47. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
Technician B
An uninsulated TXV sensing bulb
An overcharged system
The sight glass is full of liquid+the sight glass is full of gas

48. 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
Low discharge pressure - high suction pressure - and low amp draw
Technician A
Evaporator and compressor
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

49. A hard-start kit consists of...
('Y' and 'C') and ('G' and 'C')
Low voltage and a faulty start relay
A start capacitor and a solid-state relay
Increases starting torque

50. 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 restricted metering device
Current in the compressor circuit
50-65
The external equalizer could be plugged