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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. 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
An uninsulated TXV sensing bulb
Condenser fans operating during a low ambient condition and a low suction pressure
An overcharged system

2. 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
High suction pressure and low superheat
Technician A
An open internal overload protector
Low voltage and a faulty start relay

3. What component is most often the cause of a start capacitor failure...
Both technicians are incorrect
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A start relay
A missing air filter+improper rotation of the indoor blower+blower too small

4. Air filters should be replaced...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Whenever necessary
Current in the compressor circuit
An uninsulated TXV sensing bulb

5. 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
It is used to control refrigerant pressure in the compressor crankcase
An undercharged system+insufficient airflow over the evaporator coil
Technician B
A plugged filter drier

6. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It would cause the low-side pressure to decrease
An increase in suction pressure and an increase in discharge pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Dirty condenser - bent condenser fins - and air recirculating over the condenser

7. 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
Rise more than normal
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Run with high head and high suction pressure

8. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
High suction pressure and low superheat
Broken rings+broken valves+seized bearings
Contains a solenoid coil and one or more sets of contacts

9. A hard-start kit for an air conditioning system...
Increases starting torque
An uninsulated TXV sensing bulb
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

10. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Short cycling and insufficient dehumidification
Both technicians are correct
A missing air filter+improper rotation of the indoor blower+blower too small
It would cause the low-side pressure to decrease

11. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
An acid-core suction line drier
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Run with high head and high suction pressure
A low refrigerant charge

12. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Both technicians are correct
The superheat will increase and the low-side pressure will decrease
High suction pressure and low superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted

13. A liquid-charged TXV bulb will...
Technician B
Always have some liquid present in the bulb and diaphragm
Partially frosted evaporator and high superheat
The internal overload is opened

14. What is the purpose of the TXV...
Bad compressor valve
Technician B
An increase of air leakage from ductwork
It keeps a constant superheat in the evaporator

15. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
Both technicians are incorrect
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B

16. What is the common cause of a compressor burnout...
Evaporator and compressor
A low refrigerant charge
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An undercharged system+insufficient airflow over the evaporator coil

17. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
A vacuum test+oil traces around fittings+soap bubble solution
Technician A is correct
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

18. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A bad thermostat
The superheat will increase and the low-side pressure will decrease
Bad compressor valve

19. 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
High superheat and low discharge pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B

20. 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...
An uninsulated TXV sensing bulb
Increases starting torque
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A blown fuse

21. What is the purpose of a CPR valve...
Current in the compressor circuit
It is used to control refrigerant pressure in the compressor crankcase
('Y' and 'C') and ('G' and 'C')
The internal overload is opened

22. 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
Technician B
Lack of airflow
It would cause the low-side pressure to decrease

23. 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...
Short cycling and insufficient dehumidification
An acid-core suction line drier
An increase of air leakage from ductwork
High superheat and low discharge pressure

24. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
Low discharge pressure - high suction pressure - and low amp draw
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

25. What are two problems that can cause an air conditioning system to have an excessively high superheat...
The external equalizer could be plugged
3 psig
A blown fuse
An uninsulated suction line and a restricted metering device

26. 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
High suction pressure and low superheat
A restricted metering device
The external equalizer could be plugged
A sensing bulb improperly connected to the suction line

27. 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...
It is used to control refrigerant pressure in the compressor crankcase
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The low-side pressure will decrease and the evaporator coil will be partially frosted
Condenser fans operating during a low ambient condition and a low suction pressure

28. A hard-start kit consists of...
Condenser fans operating during a low ambient condition and a low suction pressure
A start capacitor and a solid-state relay
A low refrigerant charge
50-65

29. The internal overload of an air conditioning compressor senses winding temperature and...
Condenser fans operating during a low ambient condition and a low suction pressure
The external equalizer could be plugged
Current in the compressor circuit
A start capacitor and a solid-state relay

30. 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
It is used to control refrigerant pressure in the compressor crankcase
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A vacuum test+oil traces around fittings+soap bubble solution

31. 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
Low superheat
An open internal overload protector
Technician B

32. 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
Run with high head and high suction pressure
A low refrigerant charge
Broken rings+broken valves+seized bearings
Both technicians are incorrect

33. Why is it unsafe to operate an air conditioning system with a low charge...
It keeps a constant superheat in the evaporator
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
A missing air filter+improper rotation of the indoor blower+blower too small

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
Clean the condenser coil
It is used to control refrigerant pressure in the compressor crankcase
Condenser fans operating during a low ambient condition and a low suction pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan

35. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
('Y' and 'C') and ('G' and 'C')
Current in the compressor circuit
Both technicians are correct

36. 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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37. What are the operating pressures of an oil pressure safety switch...
Lack of airflow
Current in the compressor circuit
The oil pump pressure and the crankcase pressure
Technician B

38. What three things can prevent an air conditioning system from releasing heat at the proper rate...
('Y' and 'C') and ('G' and 'C')
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

39. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The oil pump pressure and the crankcase pressure
An increase in low-side pressure
The discharge pressure increases and the amperage increases
An overcharged system

40. 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
('Y' and 'C') and ('G' and 'C')
Technician B
Low superheat
Both technicians are incorrect

41. 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 superheat increases and the subcooling decreases
Contains a solenoid coil and one or more sets of contacts
Increases starting torque
Technician B

42. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The system has been overcharged+The system has air trapped in the condenser
110-120
Technician B
20 to 30

43. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Short cycling and insufficient dehumidification
The sight glass is full of liquid+the sight glass is full of gas
An acid-core suction line drier
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

44. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
An increase in low-side pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An undercharged system+insufficient airflow over the evaporator coil

45. A compressor motor starts and operates for a short period of time and cycles on the external overload protector. What are two possible problems that could cause this...
The sensing bulb at a lower temperature than the valve body
An undercharge and low ambient conditions
Low voltage and a faulty start relay
An undercharge and low ambient conditions

46. A customer calls with an insufficient cooling complaint on a 90
Technician B
The oil pump pressure and the crankcase pressure
A start capacitor and a solid-state relay
The internal overload is opened

47. The best description of a relay would be...
Clean the condenser coil
A defective circuit breaker
Contains a solenoid coil and one or more sets of contacts
Rise more than normal

48. 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
Evaporator and compressor
An increase of air leakage from ductwork
A bad thermostat
The superheat increases and the subcooling decreases

49. 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
An acid-core suction line drier
50-65
Lack of airflow
Technician A

50. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Technician B
A sensing bulb improperly connected to the suction line
An increase in suction pressure and an increase in discharge pressure
An overcharged system