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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 a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
Partially frosted evaporator and high superheat
A missing air filter+improper rotation of the indoor blower+blower too small
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

2. 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...
An open internal overload protector
Condenser fans operating during a low ambient condition and a low suction pressure
A blown fuse
It is used to control refrigerant pressure in the compressor crankcase

3. Which of the following will cause excessive discharge pressures on an air conditioning system...
20 to 30
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B
An increase of air leakage from ductwork

4. What component is most often the cause of a start capacitor failure...
Technician A
A start relay
Technician B
An increase in suction pressure and an increase in discharge pressure

5. What is the purpose of the TXV...
It is used to control refrigerant pressure in the compressor crankcase
Lack of airflow
It keeps a constant superheat in the evaporator
Evaporator and compressor

6. 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
A start capacitor and a solid-state relay
An open internal overload protector
Technician A
Technician B

7. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
Low voltage and a faulty start relay
('Y' and 'C') and ('G' and 'C')
The sight glass is full of liquid+the sight glass is full of gas

8. 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
An undercharge and low ambient conditions
50-65
A bad thermostat
'G' to 'C'

9. The temperature range of the suction line from an air conditioning system should be...
A low refrigerant charge
50-65
Flooding the condenser - cycling condenser fans - and dampering condenser air
The discharge pressure increases and the amperage increases

10. A system that uses a thermal electric expansion valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Broken rings+broken valves+seized bearings
An overcharged system
A blown fuse

11. Air filters should be replaced...
Whenever necessary
The oil pump pressure and the crankcase pressure
The discharge pressure increases and the amperage increases
The sensing bulb at a lower temperature than the valve body

12. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Broken rings+broken valves+seized bearings
An increase in suction pressure and an increase in discharge pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

13. 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
The system has been overcharged+The system has air trapped in the condenser
The discharge pressure increases and the amperage increases
It keeps a constant superheat in the evaporator

14. 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
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A start relay
Current in the compressor circuit

15. What is the purpose of an EPR valve...
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Contains a solenoid coil and one or more sets of contacts

16. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
A restricted metering device
Technician B
High superheat and low discharge pressure

17. Which of the following is a common cause of an excessively low superheat on a TXV system...
Technician B
110-120
A sensing bulb improperly connected to the suction line
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

18. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
Technician B
Low discharge pressure - high suction pressure - and low amp draw
An increase in low-side pressure

19. 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
Whenever necessary
('Y' and 'C') and ('G' and 'C')
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician A is correct

20. 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
Contains a solenoid coil and one or more sets of contacts
A defective circuit breaker
An undercharged system+insufficient airflow over the evaporator coil

21. What problem or problems can cause low discharge and suction pressure...
20 to 30
The system has been overcharged+The system has air trapped in the condenser
High suction pressure and low superheat
An undercharged system+insufficient airflow over the evaporator coil

22. A commercial customer calls on a 90
Low voltage and a faulty start relay
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system has been overcharged+The system has air trapped in the condenser
Contains a solenoid coil and one or more sets of contacts

23. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A start capacitor and a solid-state relay
An uninsulated suction line and a restricted metering device
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Flooding the condenser - cycling condenser fans - and dampering condenser air

24. Which of the following can cause excessive subcooling...
The sensing bulb at a lower temperature than the valve body
An increase in suction pressure and an increase in discharge pressure
An overcharged system
Technician A is correct

25. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The superheat increases and the subcooling decreases
An increase in low-side pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Low discharge pressure - high suction pressure - and low amp draw

26. 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
An open internal overload protector
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
('Y' and 'C') and ('G' and 'C')

27. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Rise more than normal
A missing air filter+improper rotation of the indoor blower+blower too small
Low discharge pressure - high suction pressure - and low amp draw
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

28. 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
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A low refrigerant charge
The sensing bulb at a lower temperature than the valve body

29. 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
The discharge pressure increases and the amperage increases
Clean the condenser coil
Partially frosted evaporator and high superheat

30. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The discharge pressure increases and the amperage increases
Technician B
Broken rings+broken valves+seized bearings
20 to 30

31. 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
Technician B
Run with high head and high suction pressure
An increase of air leakage from ductwork

32. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Partially frosted evaporator and high superheat
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in suction pressure and an increase in discharge pressure
The external equalizer could be plugged

33. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
A start capacitor and a solid-state relay

34. What causes the automatic expansion valve to close...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An increase in low-side pressure
The superheat will increase and the low-side pressure will decrease
Condenser fans operating during a low ambient condition and a low suction pressure

35. 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 start capacitor and a solid-state relay
Technician B
Technician A is correct
A bad thermostat

36. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Broken rings+broken valves+seized bearings
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Evaporator and compressor

37. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The internal overload is opened
Low discharge pressure - high suction pressure - and low amp draw
Whenever necessary
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

38. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Low discharge pressure - high suction pressure - and low amp draw
It is used to control refrigerant pressure in the compressor crankcase
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

39. 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
The sight glass is full of liquid+the sight glass is full of gas
Low superheat
A defective circuit breaker
The system has been overcharged+The system has air trapped in the condenser

40. A compressor having tight bearings would cause the current value to...
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
Condenser fans operating during a low ambient condition and a low suction pressure
Rise more than normal

41. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A defective circuit breaker
Condenser fans operating during a low ambient condition and a low suction pressure
An overcharged system
Technician B

42. 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
Both technicians are incorrect
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

43. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An uninsulated suction line and a restricted metering device
High superheat and low discharge pressure
The oil pump pressure and the crankcase pressure

44. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Evaporator and compressor
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Contains a solenoid coil and one or more sets of contacts

45. What are common methods that are used for leak-testing a system...
A restricted metering device
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B
A vacuum test+oil traces around fittings+soap bubble solution

46. Which of the following is a common cause of an excessively low superheat on a TXV system...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The sensing bulb at a lower temperature than the valve body
A sensing bulb improperly connected to the suction line

47. What are common methods that are used for leak-testing a system...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Both technicians are incorrect
A sensing bulb improperly connected to the suction line
A vacuum test+oil traces around fittings+soap bubble solution

48. 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 overcharged system
An uninsulated suction line and a restricted metering device
Low voltage and a faulty start relay

49. A customer calls with an insufficient cooling complaint on a 90
Technician B
The superheat will increase and the low-side pressure will decrease
The low-side pressure will decrease and the evaporator coil will be partially frosted
Low superheat

50. A hard-start kit consists of...
A start capacitor and a solid-state relay
Low superheat
50-65
Lack of airflow