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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. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Low superheat
A missing air filter+improper rotation of the indoor blower+blower too small
'G' to 'C'
An increase of air leakage from ductwork

2. What causes the automatic expansion valve to close...
An increase in low-side pressure
A defective circuit breaker
Clean the condenser coil
Technician B

3. 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
The oil pump pressure and the crankcase pressure
High suction pressure and low superheat
Run with high head and high suction pressure

4. What is the purpose of an EPR valve...
Broken rings+broken valves+seized bearings
110-120
20 to 30
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

5. Superheat is found in an air conditioning system in the...
Technician B
Run with high head and high suction pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Evaporator and compressor

6. 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
It keeps a constant superheat in the evaporator
A defective circuit breaker
An uninsulated suction line and a restricted metering device
Broken rings+broken valves+seized bearings

7. Superheat is found in an air conditioning system in the...
The system has been overcharged+The system has air trapped in the condenser
Evaporator and compressor
Bad compressor valve
110-120

8. 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...
It keeps a constant superheat in the evaporator
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Low voltage and a faulty start relay

9. A system that is operating with a clear sight glass shows...
Broken rings+broken valves+seized bearings
A low refrigerant charge
The sight glass is full of liquid+the sight glass is full of gas
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

10. 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
An undercharge and low ambient conditions
Both technicians are incorrect
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Low voltage and a faulty start relay

11. What are two problems that can cause an air conditioning system to have an excessively high superheat...
The discharge pressure increases and the amperage increases
An open internal overload protector
Always have some liquid present in the bulb and diaphragm
An uninsulated suction line and a restricted metering device

12. 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...
('Y' and 'C') and ('G' and 'C')
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The internal overload is opened
It keeps a constant superheat in the evaporator

13. Which of the following can cause low superheat in a TXV system...
Bad compressor valve
A bad thermostat
An uninsulated TXV sensing bulb
A missing air filter+improper rotation of the indoor blower+blower too small

14. What are the symptoms of an air conditioning system that has a low charge...
50-65
The low-side pressure will decrease and the evaporator coil will be partially frosted
Contains a solenoid coil and one or more sets of contacts
Lack of airflow

15. 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 vacuum test+oil traces around fittings+soap bubble solution
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A start relay

16. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Run with high head and high suction pressure
Condenser fans operating during a low ambient condition and a low suction pressure
Both technicians are incorrect
An increase in low-side pressure

17. 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 superheat increases and the subcooling decreases
A start capacitor and a solid-state relay
Both technicians are incorrect
The system has been overcharged+The system has air trapped in the condenser

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
Clean the condenser coil
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Both technicians are incorrect

19. When using a vapor-charged TXV bulb - it is necessary to have...
The system has been overcharged+The system has air trapped in the condenser
The sensing bulb at a lower temperature than the valve body
Broken rings+broken valves+seized bearings
An uninsulated suction line and a restricted metering device

20. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Evaporator and compressor
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The discharge pressure increases and the amperage increases
A plugged filter drier

21. A hard-start kit consists of...
('Y' and 'C') and ('G' and 'C')
A start capacitor and a solid-state relay
Clean the condenser coil
Whenever necessary

22. 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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23. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
'G' to 'C'
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

24. Air filters should be replaced...
Broken rings+broken valves+seized bearings
Both technicians are incorrect
Whenever necessary
A bad thermostat

25. A compressor having tight bearings would cause the current value to...
Rise more than normal
A defective circuit breaker
Low voltage and a faulty start relay
Technician B

26. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Both technicians are incorrect
A missing air filter+improper rotation of the indoor blower+blower too small
20 to 30

27. 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 uninsulated TXV sensing bulb
Both technicians are incorrect
The low-side pressure will decrease and the evaporator coil will be partially frosted
A bad thermostat

28. 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
It keeps a constant superheat in the evaporator
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
It would cause the low-side pressure to decrease
Technician A is correct

29. The internal overload of an air conditioning compressor senses winding temperature and...
Technician A
An uninsulated TXV sensing bulb
Current in the compressor circuit
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

30. 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
A bad thermostat
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Current in the compressor circuit

31. A commercial customer calls on a 90
A low refrigerant charge
The system has been overcharged+The system has air trapped in the condenser
Low superheat
50-65

32. A liquid-charged TXV bulb will...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Always have some liquid present in the bulb and diaphragm
Technician A
A bad thermostat

33. 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
Both technicians are incorrect
Technician B
The oil pump pressure and the crankcase pressure
An increase of air leakage from ductwork

34. What is the purpose of a CPR valve...
An undercharge and low ambient conditions
50-65
A defective circuit breaker
It is used to control refrigerant pressure in the compressor crankcase

35. Which of the following is a common cause of an excessively low superheat on a TXV system...
Increases starting torque
Technician B
A sensing bulb improperly connected to the suction line
A bad thermostat

36. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The system has been overcharged+The system has air trapped in the condenser
Bad compressor valve
The oil pump pressure and the crankcase pressure

37. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A missing air filter+improper rotation of the indoor blower+blower too small
Increases starting torque
Contains a solenoid coil and one or more sets of contacts

38. The temperature range of the suction line from an air conditioning system should be...
50-65
A blown fuse
3 psig
A defective circuit breaker

39. Why is it unsafe to operate an air conditioning system with a low charge...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Clean the condenser coil
Low superheat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

40. 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...
An uninsulated suction line and a restricted metering device
The internal overload is opened
Low voltage and a faulty start relay
'G' to 'C'

41. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An open internal overload protector
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A dirty condenser - recirculation of condenser air - and a defective condenser fan

42. 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 dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An uninsulated suction line and a restricted metering device
High superheat and low discharge pressure
High suction pressure and low superheat

43. 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
A defective circuit breaker
Rise more than normal
Dirty condenser - bent condenser fins - and air recirculating over the condenser

44. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
An increase in low-side pressure
An uninsulated suction line and a restricted metering device
A dirty condenser - recirculation of condenser air - and a defective condenser fan

45. 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
Condenser fans operating during a low ambient condition and a low suction pressure
('Y' and 'C') and ('G' and 'C')
Technician A
Run with high head and high suction pressure

46. A customer calls with an insufficient cooling complaint on a 90
A restricted metering device
An increase in suction pressure and an increase in discharge pressure
An overcharged system
Technician B

47. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Condenser fans operating during a low ambient condition and a low suction pressure
An increase in suction pressure and an increase in discharge pressure
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

48. What is the purpose of an EPR valve...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Whenever necessary
A blown fuse
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

49. Which of the following can cause low superheat in a TXV system...
Clean the condenser coil
Increases starting torque
Technician B
An uninsulated TXV sensing bulb

50. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
An overcharged system
Low discharge pressure - high suction pressure - and low amp draw
The external equalizer could be plugged
Both technicians are incorrect