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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 possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
An increase in suction pressure and an increase in discharge pressure
3 psig
50-65
A plugged filter drier

2. 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
A plugged filter drier
Current in the compressor circuit
Run with high head and high suction pressure

3. A restricted air filter in an air conditioning system can be identified by...
Low superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It would cause the low-side pressure to decrease
Dirty condenser - bent condenser fins - and air recirculating over the condenser

4. 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 plugged filter drier
Bad compressor valve
The internal overload is opened
The superheat increases and the subcooling decreases

5. 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
Both technicians are correct
Condenser fans operating during a low ambient condition and a low suction pressure
20 to 30
High superheat and low discharge pressure

6. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
The superheat increases and the subcooling decreases
20 to 30
A dirty condenser - recirculation of condenser air - and a defective condenser fan

7. A system that uses a thermal electric expansion valve...
A low refrigerant charge
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
3 psig
20 to 30

8. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
'G' to 'C'
An acid-core suction line drier
Dirty condenser - bent condenser fins - and air recirculating over the condenser

9. 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
'G' to 'C'
Technician B
High suction pressure and low superheat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

10. 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 has been overcharged+The system has air trapped in the condenser
The external equalizer could be plugged
Technician A
Technician B

11. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Broken rings+broken valves+seized bearings
Both technicians are incorrect
Evaporator and compressor

12. 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 low refrigerant charge
Partially frosted evaporator and high superheat
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Broken rings+broken valves+seized bearings

13. 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 superheat increases and the subcooling decreases
An open internal overload protector
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

14. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
The superheat increases and the subcooling decreases
The sensing bulb at a lower temperature than the valve body
Contains a solenoid coil and one or more sets of contacts

15. 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
Both technicians are incorrect
Lack of airflow
A start capacitor and a solid-state relay
Technician B

16. Which of the following is a common cause of an excessively low superheat on a TXV system...
110-120
A sensing bulb improperly connected to the suction line
A low refrigerant charge
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

17. A compressor having tight bearings would cause the current value to...
Technician B
An undercharged system+insufficient airflow over the evaporator coil
Rise more than normal
Low superheat

18. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Contains a solenoid coil and one or more sets of contacts
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An increase in suction pressure and an increase in discharge pressure
Low superheat

19. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
50-65
Both technicians are correct
The sight glass is full of liquid+the sight glass is full of gas

20. 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
('Y' and 'C') and ('G' and 'C')
Technician B
The discharge pressure increases and the amperage increases
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

21. 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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22. What are the symptoms of an air conditioning system that has a low charge...
The discharge pressure increases and the amperage increases
Flooding the condenser - cycling condenser fans - and dampering condenser air
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician A is correct

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...
Both technicians are incorrect
Partially frosted evaporator and high superheat
High superheat and low discharge pressure
Technician B

24. What problem or problems can cause low discharge and suction pressure...
Evaporator and compressor
A defective circuit breaker
An undercharged system+insufficient airflow over the evaporator coil
An uninsulated suction line and a restricted metering device

25. What type of problems can be caused by an oversized air conditioning system...
The system has been overcharged+The system has air trapped in the condenser
The sight glass is full of liquid+the sight glass is full of gas
Short cycling and insufficient dehumidification
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

26. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A blown fuse
The low-side pressure will decrease and the evaporator coil will be partially frosted
The superheat will increase and the low-side pressure will decrease

27. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A missing air filter+improper rotation of the indoor blower+blower too small
The superheat increases and the subcooling decreases
It keeps a constant superheat in the evaporator
An overcharged system

28. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
Lack of airflow

29. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A defective circuit breaker
A bad thermostat
20 to 30
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

30. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Rise more than normal
The superheat will increase and the low-side pressure will decrease
110-120
The sensing bulb at a lower temperature than the valve body

31. 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
The sensing bulb at a lower temperature than the valve body
Contains a solenoid coil and one or more sets of contacts
Both technicians are incorrect
It would cause the low-side pressure to decrease

32. What is the purpose of a CPR valve...
Always have some liquid present in the bulb and diaphragm
It is used to control refrigerant pressure in the compressor crankcase
The external equalizer could be plugged
Both technicians are incorrect

33. Which of the following is a possible cause for a compressor to overheat...
Technician B
Whenever necessary
The discharge pressure increases and the amperage increases
A low refrigerant charge

34. 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...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Both technicians are incorrect
The system has been overcharged+The system has air trapped in the condenser
A blown fuse

35. 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
An undercharge and low ambient conditions
A low refrigerant charge
A start capacitor and a solid-state relay
Both technicians are incorrect

36. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
Bad compressor valve
A low refrigerant charge
An overcharged system

37. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
'G' to 'C'
Technician B
Increases starting torque

38. 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
Rise more than normal
A defective circuit breaker
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

39. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Condenser fans operating during a low ambient condition and a low suction pressure
Technician A
The superheat increases and the subcooling decreases
Condenser fans operating during a low ambient condition and a low suction pressure

40. 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
An undercharged system+insufficient airflow over the evaporator coil
An increase in suction pressure and an increase in discharge pressure
High suction pressure and low superheat

41. 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...
Broken rings+broken valves+seized bearings
Condenser fans operating during a low ambient condition and a low suction pressure
Both technicians are incorrect
Run with high head and high suction pressure

42. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A plugged filter drier
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Current in the compressor circuit
An increase in suction pressure and an increase in discharge pressure

43. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
A start capacitor and a solid-state relay
The external equalizer could be plugged
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

44. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A missing air filter+improper rotation of the indoor blower+blower too small
Broken rings+broken valves+seized bearings
Technician A is correct

45. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The oil pump pressure and the crankcase pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
Whenever necessary

46. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Clean the condenser coil
Run with high head and high suction pressure
Low discharge pressure - high suction pressure - and low amp draw
Whenever necessary

47. A customer calls with an insufficient cooling complaint on a 90
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
High superheat and low discharge pressure

48. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Technician B
It would cause the low-side pressure to decrease
An uninsulated suction line and a restricted metering device
Technician B

49. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Technician B
3 psig
110-120
Both technicians are correct

50. 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...
Low superheat
A plugged filter drier
High superheat and low discharge pressure
Technician A is correct