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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 is the common cause of a compressor burnout...
A start capacitor and a solid-state relay
Broken rings+broken valves+seized bearings
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The oil pump pressure and the crankcase pressure

2. What causes the automatic expansion valve to close...
High superheat and low discharge pressure
Technician B
Lack of airflow
An increase in low-side pressure

3. 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 superheat increases and the subcooling decreases
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An increase in low-side pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

4. 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
High superheat and low discharge pressure
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Whenever necessary

5. A customer calls and says that her air conditioning system is not cooling properly. Upon arrival - a technician notices that the suction line and compressor have frost buildup. Technician A says that the problem is probably a low charge. Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The oil pump pressure and the crankcase pressure
The sight glass is full of liquid+the sight glass is full of gas
Technician B

6. 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
20 to 30
A start relay
Both technicians are incorrect

7. 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
Both technicians are correct
The sight glass is full of liquid+the sight glass is full of gas
Run with high head and high suction pressure
Technician A

8. Air filters should be replaced...
A bad thermostat
Whenever necessary
Low superheat
Short cycling and insufficient dehumidification

9. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Technician B
The sight glass is full of liquid+the sight glass is full of gas
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Bad compressor valve

10. 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
It is used to control refrigerant pressure in the compressor crankcase
Broken rings+broken valves+seized bearings
Lack of airflow

11. What component is most often the cause of a start capacitor failure...
The internal overload is opened
A start relay
Lack of airflow
The sensing bulb at a lower temperature than the valve body

12. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A bad thermostat
Technician B
An overcharged system
Technician B

13. Why is it unsafe to operate an air conditioning system with a low charge...
Short cycling and insufficient dehumidification
Rise more than normal
The discharge pressure increases and the amperage increases
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

14. What type of problems can be caused by an oversized air conditioning system...
Low superheat
High superheat and low discharge pressure
Technician A is correct
Short cycling and insufficient dehumidification

15. Which of the following can cause excessive subcooling...
An overcharged system
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

16. A hard-start kit consists of...
A start capacitor and a solid-state relay
An acid-core suction line drier
Technician A
An uninsulated TXV sensing bulb

17. What problem or problems can cause low discharge and suction pressure...
An uninsulated TXV sensing bulb
An undercharged system+insufficient airflow over the evaporator coil
An uninsulated suction line and a restricted metering device
A sensing bulb improperly connected to the suction line

18. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An increase in low-side pressure
An undercharge and low ambient conditions
An uninsulated suction line and a restricted metering device
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

19. A restricted air filter in an air conditioning system can be identified by...
Technician B
Whenever necessary
The superheat will increase and the low-side pressure will decrease
Low superheat

20. 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
An increase of air leakage from ductwork
Broken rings+broken valves+seized bearings
A plugged filter drier
Technician B

21. 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
A sensing bulb improperly connected to the suction line
Both technicians are correct
The sensing bulb at a lower temperature than the valve body
('Y' and 'C') and ('G' and 'C')

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
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The discharge pressure increases and the amperage increases

23. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Technician A is correct
An overcharged system
A plugged filter drier
The system has been overcharged+The system has air trapped in the condenser

24. Superheat is found in an air conditioning system in the...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Evaporator and compressor
A start relay
A vacuum test+oil traces around fittings+soap bubble solution

25. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...

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26. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A sensing bulb improperly connected to the suction line
A missing air filter+improper rotation of the indoor blower+blower too small
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The external equalizer could be plugged

27. Which of the following could be the cause for a system's discharge and suction pressure being low...
Technician B
A restricted metering device
A plugged filter drier
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

28. What are common methods that are used for leak-testing a system...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
'G' to 'C'
A vacuum test+oil traces around fittings+soap bubble solution

29. A system that uses a thermal electric expansion valve...
An overcharged system
The superheat increases and the subcooling decreases
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

30. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
Lack of airflow
Both technicians are incorrect

31. What are three methods for controlling a system's high-side pressure during low ambient conditions...
An increase in suction pressure and an increase in discharge pressure
A low refrigerant charge
An undercharged system+insufficient airflow over the evaporator coil
Flooding the condenser - cycling condenser fans - and dampering condenser air

32. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Partially frosted evaporator and high superheat
The oil pump pressure and the crankcase pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air

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
An overcharged system
3 psig
An increase in suction pressure and an increase in discharge pressure
A defective circuit breaker

34. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...

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35. 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
An uninsulated TXV sensing bulb
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Both technicians are incorrect

36. The technician observes that the compressor is not operating. The compressor windings read 5 ohms start to run - run to common is opened - and start to common is opened. The technician concludes that...
A start relay
Whenever necessary
The internal overload is opened
An increase in suction pressure and an increase in discharge pressure

37. A customer calls with an insufficient cooling complaint on a 90
An open internal overload protector
A start capacitor and a solid-state relay
An uninsulated TXV sensing bulb
Technician B

38. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Flooding the condenser - cycling condenser fans - and dampering condenser air
50-65
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

39. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small
Contains a solenoid coil and one or more sets of contacts
Increases starting torque

40. The internal overload of an air conditioning compressor senses winding temperature and...
The external equalizer could be plugged
Current in the compressor circuit
Low voltage and a faulty start relay
A plugged filter drier

41. 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
Bad compressor valve
Contains a solenoid coil and one or more sets of contacts
Both technicians are incorrect
A dirty condenser - recirculation of condenser air - and a defective condenser fan

42. 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 defective circuit breaker
20 to 30
It would cause the low-side pressure to decrease
Current in the compressor circuit

43. 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...
Technician B
Current in the compressor circuit
A defective circuit breaker
A blown fuse

44. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Broken rings+broken valves+seized bearings
Evaporator and compressor

45. A hard-start kit for an air conditioning system...
The superheat increases and the subcooling decreases
An overcharged system
Increases starting torque
The superheat will increase and the low-side pressure will decrease

46. 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
The internal overload is opened
A bad thermostat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An open internal overload protector

47. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Contains a solenoid coil and one or more sets of contacts
Whenever necessary

48. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Broken rings+broken valves+seized bearings
Technician B
An undercharge and low ambient conditions

49. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B

50. Why is it unsafe to operate an air conditioning system with a low charge...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A defective circuit breaker
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil