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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 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
Technician B
Bad compressor valve
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

2. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
Whenever necessary
High superheat and low discharge pressure
A start relay

3. What type of problems can be caused by an oversized air conditioning system...
A start relay
Short cycling and insufficient dehumidification
A missing air filter+improper rotation of the indoor blower+blower too small
A low refrigerant charge

4. 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 external equalizer could be plugged
Low voltage and a faulty start relay
Technician B
Technician B

5. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
Broken rings+broken valves+seized bearings
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

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
An increase in suction pressure and an increase in discharge pressure
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure
The system has been overcharged+The system has air trapped in the condenser

7. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The superheat increases and the subcooling decreases
110-120
Both technicians are correct
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

8. When using a vapor-charged TXV bulb - it is necessary to have...
A missing air filter+improper rotation of the indoor blower+blower too small
The sensing bulb at a lower temperature than the valve body
Technician B
Both technicians are incorrect

9. What problem or problems can cause low discharge and suction pressure...
The sensing bulb at a lower temperature than the valve body
20 to 30
High suction pressure and low superheat
An undercharged system+insufficient airflow over the evaporator coil

10. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
Both technicians are incorrect
An uninsulated TXV sensing bulb
The external equalizer could be plugged

11. What is the purpose of the TXV...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
It keeps a constant superheat in the evaporator
A start capacitor and a solid-state relay

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
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
Clean the condenser coil
The external equalizer could be plugged

13. 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
An undercharged system+insufficient airflow over the evaporator coil
A low refrigerant charge
The external equalizer could be plugged

14. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
A bad thermostat
An undercharged system+insufficient airflow over the evaporator coil
'G' to 'C'

15. The best description of a relay would be...
The oil pump pressure and the crankcase pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Contains a solenoid coil and one or more sets of contacts
The oil pump pressure and the crankcase pressure

16. 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
The internal overload is opened
Technician B
Partially frosted evaporator and high superheat
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

17. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
Technician A is correct
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It is used to control refrigerant pressure in the compressor crankcase

18. 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
A start capacitor and a solid-state relay
Technician B
Both technicians are correct
Low voltage and a faulty start relay

19. What is the purpose of the TXV...
The sensing bulb at a lower temperature than the valve body
It keeps a constant superheat in the evaporator
Both technicians are correct
It would cause the low-side pressure to decrease

20. Which of the following can cause low superheat in a TXV system...
The superheat increases and the subcooling decreases
It is used to control refrigerant pressure in the compressor crankcase
An uninsulated TXV sensing bulb
The external equalizer could be plugged

21. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
Technician B
An overcharged system
High superheat and low discharge pressure

22. What type of problems can be caused by an oversized air conditioning system...
Rise more than normal
A start capacitor and a solid-state relay
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Short cycling and insufficient dehumidification

23. What are the operating pressures of an oil pressure safety switch...
A blown fuse
An acid-core suction line drier
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The oil pump pressure and the crankcase pressure

24. 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
High superheat and low discharge pressure
Run with high head and high suction pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

25. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A missing air filter+improper rotation of the indoor blower+blower too small
An uninsulated TXV sensing bulb
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase of air leakage from ductwork

26. What are the symptoms of a TXV air conditioning system if it has lost its charge...
An increase of air leakage from ductwork
Run with high head and high suction pressure
The superheat will increase and the low-side pressure will decrease
Both technicians are correct

27. Which of the following is a common cause of an excessively low superheat on a TXV system...
A start capacitor and a solid-state relay
A sensing bulb improperly connected to the suction line
A vacuum test+oil traces around fittings+soap bubble solution
A restricted metering device

28. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
The sensing bulb at a lower temperature than the valve body
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
20 to 30
Technician B

29. What is the common cause of a compressor burnout...
An open internal overload protector
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
Broken rings+broken valves+seized bearings

30. 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
A defective circuit breaker
Broken rings+broken valves+seized bearings
The internal overload is opened
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

31. A commercial customer calls on a 90
An uninsulated TXV sensing bulb
Both technicians are incorrect
The system has been overcharged+The system has air trapped in the condenser
It keeps a constant superheat in the evaporator

32. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
3 psig
Short cycling and insufficient dehumidification
The external equalizer could be plugged
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

33. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
Run with high head and high suction pressure

34. 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...
High superheat and low discharge pressure
An undercharged system+insufficient airflow over the evaporator coil
The oil pump pressure and the crankcase pressure
A missing air filter+improper rotation of the indoor blower+blower too small

35. 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 overcharged system
Bad compressor valve
Evaporator and compressor
Broken rings+broken valves+seized bearings

36. What component is most often the cause of a start capacitor failure...
A start relay
An acid-core suction line drier
A plugged filter drier
Clean the condenser coil

37. 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...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The superheat will increase and the low-side pressure will decrease
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
High superheat and low discharge pressure

38. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
A defective circuit breaker
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Low discharge pressure - high suction pressure - and low amp draw

39. What three things can prevent an air conditioning system from releasing heat at the proper rate...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The low-side pressure will decrease and the evaporator coil will be partially frosted

40. 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
An open internal overload protector
Technician A
Technician B
The system has been overcharged+The system has air trapped in the condenser

41. A system that uses a thermal electric expansion valve...
Current in the compressor circuit
('Y' and 'C') and ('G' and 'C')
High suction pressure and low superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

42. Air filters should be replaced...
A restricted metering device
A bad thermostat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Whenever necessary

43. Which of the following could be the cause for a system's discharge and suction pressure being low...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Low discharge pressure - high suction pressure - and low amp draw
A restricted metering device
A bad thermostat

44. A hard-start kit for an air conditioning system...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Increases starting torque
The oil pump pressure and the crankcase pressure
It keeps a constant superheat in the evaporator

45. A compressor having tight bearings would cause the current value to...
Rise more than normal
High superheat and low discharge pressure
A start capacitor and a solid-state relay
Partially frosted evaporator and high superheat

46. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
Both technicians are correct
Increases starting torque
Low voltage and a faulty start relay

47. What causes the automatic expansion valve to close...
Both technicians are incorrect
An increase in low-side pressure
A restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

48. What is the purpose of an EPR valve...
Always have some liquid present in the bulb and diaphragm
The discharge pressure increases and the amperage increases
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Low superheat

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

50. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
The external equalizer could be plugged
A low refrigerant charge
Contains a solenoid coil and one or more sets of contacts
It would cause the low-side pressure to decrease