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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. 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
The sensing bulb at a lower temperature than the valve body
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
50-65
Technician A

2. 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
It is used to control refrigerant pressure in the compressor crankcase
Technician A is correct
It would cause the low-side pressure to decrease
Clean the condenser coil

3. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Always have some liquid present in the bulb and diaphragm
An overcharged system
Lack of airflow
It keeps a constant superheat in the evaporator

4. Which of the following can cause low superheat in a TXV system...
A defective circuit breaker
An uninsulated TXV sensing bulb
Bad compressor valve
The superheat increases and the subcooling decreases

5. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Both technicians are incorrect
It keeps a constant superheat in the evaporator
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
110-120

6. 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
Technician A is correct
An increase in low-side pressure
An uninsulated TXV sensing bulb
An undercharged system+insufficient airflow over the evaporator coil

7. 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
A defective circuit breaker
Both technicians are incorrect
The discharge pressure increases and the amperage increases
Short cycling and insufficient dehumidification

8. A hard-start kit for an air conditioning system...
('Y' and 'C') and ('G' and 'C')
A restricted metering device
Increases starting torque
Bad compressor valve

9. 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
A blown fuse
The external equalizer could be plugged
A bad thermostat
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

10. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
It keeps a constant superheat in the evaporator
The discharge pressure increases and the amperage increases
A sensing bulb improperly connected to the suction line
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

11. 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
20 to 30
Broken rings+broken valves+seized bearings
Technician B
Short cycling and insufficient dehumidification

12. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Always have some liquid present in the bulb and diaphragm
The superheat increases and the subcooling decreases
The discharge pressure increases and the amperage increases
Technician B

13. Superheat is found in an air conditioning system in the...
A start relay
An increase in low-side pressure
An open internal overload protector
Evaporator and compressor

14. What are the operating pressures of an oil pressure safety switch...
Technician B
The superheat will increase and the low-side pressure will decrease
The oil pump pressure and the crankcase pressure
The superheat increases and the subcooling decreases

15. What problem or problems can cause low discharge and suction pressure...
Technician A is correct
An undercharged system+insufficient airflow over the evaporator coil
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The low-side pressure will decrease and the evaporator coil will be partially frosted

16. 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
('Y' and 'C') and ('G' and 'C')
Both technicians are incorrect
Technician A is correct
A low refrigerant charge

17. Which of the following is a possible cause for a compressor to overheat...
Technician B
A blown fuse
High superheat and low discharge pressure
A low refrigerant charge

18. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
Technician B
An open internal overload protector

19. A customer calls with an insufficient cooling complaint on a 90
A bad thermostat
The external equalizer could be plugged
Broken rings+broken valves+seized bearings
Technician B

20. 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 plugged filter drier
An undercharge and low ambient conditions
Technician B
The system has been overcharged+The system has air trapped in the condenser

21. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The superheat increases and the subcooling decreases

22. 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 overcharged system
Clean the condenser coil
High superheat and low discharge pressure
A bad thermostat

23. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The internal overload is opened
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It keeps a constant superheat in the evaporator
The discharge pressure increases and the amperage increases

24. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A plugged filter drier
Technician B

25. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated suction line and a restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small
A defective circuit breaker
Contains a solenoid coil and one or more sets of contacts

26. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
An undercharge and low ambient conditions
Both technicians are correct
Whenever necessary

27. A system that uses a thermal electric expansion valve...
20 to 30
A sensing bulb improperly connected to the suction line
Condenser fans operating during a low ambient condition and a low suction pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

28. 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...
Contains a solenoid coil and one or more sets of contacts
An increase in suction pressure and an increase in discharge pressure
An undercharged system+insufficient airflow over the evaporator coil
Condenser fans operating during a low ambient condition and a low suction pressure

29. 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
The oil pump pressure and the crankcase pressure
Technician B
High superheat and low discharge pressure
An undercharged system+insufficient airflow over the evaporator coil

30. The temperature range of the suction line from an air conditioning system should be...
50-65
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser

31. What is the purpose of the TXV...
A start relay
An undercharge and low ambient conditions
Technician B
It keeps a constant superheat in the evaporator

32. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Bad compressor valve
Technician B
An open internal overload protector
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

33. When using a vapor-charged TXV bulb - it is necessary to have...
3 psig
Run with high head and high suction pressure
Always have some liquid present in the bulb and diaphragm
The sensing bulb at a lower temperature than the valve body

34. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
Condenser fans operating during a low ambient condition and a low suction pressure
Current in the compressor circuit
An increase in suction pressure and an increase in discharge pressure

35. What causes the automatic expansion valve to close...
An increase in low-side pressure
An increase in suction pressure and an increase in discharge pressure
A start relay
An overcharged system

36. What three things can prevent an air conditioning system from releasing heat at the proper rate...
3 psig
Both technicians are incorrect
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A bad thermostat

37. 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
Whenever necessary
An undercharge and low ambient conditions
Both technicians are correct
Technician B

38. A system that is operating with a clear sight glass shows...
An increase in suction pressure and an increase in discharge pressure
Lack of airflow
The discharge pressure increases and the amperage increases
The sight glass is full of liquid+the sight glass is full of gas

39. 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 would cause the low-side pressure to decrease
Short cycling and insufficient dehumidification
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

40. A commercial customer calls on a 90
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The low-side pressure will decrease and the evaporator coil will be partially frosted
The system has been overcharged+The system has air trapped in the condenser
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

41. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An increase in suction pressure and an increase in discharge pressure
Low superheat
The discharge pressure increases and the amperage increases
Broken rings+broken valves+seized bearings

42. 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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43. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An increase of air leakage from ductwork
Bad compressor valve
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A blown fuse

44. 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
The internal overload is opened
An uninsulated TXV sensing bulb
Contains a solenoid coil and one or more sets of contacts

45. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Technician A
An acid-core suction line drier
A low refrigerant charge
Dirty condenser - bent condenser fins - and air recirculating over the condenser

46. 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
The sensing bulb at a lower temperature than the valve body
An open internal overload protector
A start capacitor and a solid-state relay
Technician B

47. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
The oil pump pressure and the crankcase pressure
Technician B
Always have some liquid present in the bulb and diaphragm

48. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
The discharge pressure increases and the amperage increases
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The external equalizer could be plugged
It would cause the low-side pressure to decrease

49. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
('Y' and 'C') and ('G' and 'C')
Run with high head and high suction pressure
A bad thermostat
Contains a solenoid coil and one or more sets of contacts

50. A hard-start kit consists of...
('Y' and 'C') and ('G' and 'C')
A blown fuse
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A start capacitor and a solid-state relay