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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 low discharge and suction pressure...
20 to 30
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An undercharged system+insufficient airflow over the evaporator coil

2. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
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 incorrect
A plugged filter drier

3. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
The external equalizer could be plugged
It would cause the low-side pressure to decrease
A plugged filter drier
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

4. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
High suction pressure and low superheat
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A restricted metering device

5. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
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
Low discharge pressure - high suction pressure - and low amp draw
A plugged filter drier

6. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A start relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An increase in suction pressure and an increase in discharge pressure

7. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An undercharge and low ambient conditions
Clean the condenser coil
Low superheat

8. The temperature range of the suction line from an air conditioning system should be...
Condenser fans operating during a low ambient condition and a low suction pressure
An undercharge and low ambient conditions
Both technicians are correct
50-65

9. Which of the following will cause excessive discharge pressures on an air conditioning system...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An increase in suction pressure and an increase in discharge pressure

10. Which of the following is a common cause of an excessively low superheat on a TXV system...
50-65
A sensing bulb improperly connected to the suction line
Technician A is correct
A defective circuit breaker

11. A customer calls with an insufficient cooling complaint on a 90
Evaporator and compressor
The oil pump pressure and the crankcase pressure
Technician B
An uninsulated suction line and a restricted metering device

12. What are two common symptoms of refrigerant leaks in an air conditioning system...
An acid-core suction line drier
Both technicians are correct
Technician A
Partially frosted evaporator and high superheat

13. What are the operating pressures of an oil pressure safety switch...
It is used to control refrigerant pressure in the compressor crankcase
The oil pump pressure and the crankcase pressure
Low superheat
A plugged filter drier

14. What component is most often the cause of a start capacitor failure...
Both technicians are incorrect
Both technicians are correct
A start relay
It would cause the low-side pressure to decrease

15. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
Contains a solenoid coil and one or more sets of contacts
The superheat increases and the subcooling decreases

16. 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...
Low voltage and a faulty start relay
The external equalizer could be plugged
Increases starting torque
Whenever necessary

17. The best description of a relay would be...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
('Y' and 'C') and ('G' and 'C')
Contains a solenoid coil and one or more sets of contacts
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

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
The internal overload is opened
An undercharged system+insufficient airflow over the evaporator coil
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B

19. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
The internal overload is opened
An acid-core suction line drier
Technician B
The external equalizer could be plugged

20. 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 overcharged system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Low superheat
Technician B

21. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Increases starting torque
A missing air filter+improper rotation of the indoor blower+blower too small
The internal overload is opened
The discharge pressure increases and the amperage increases

22. A system that uses a thermal electric expansion valve...
Lack of airflow
110-120
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

23. A liquid-charged TXV bulb will...
Current in the compressor circuit
Evaporator and compressor
A restricted metering device
Always have some liquid present in the bulb and diaphragm

24. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
A plugged filter drier
20 to 30
The low-side pressure will decrease and the evaporator coil will be partially frosted

25. Superheat is found in an air conditioning system in the...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Evaporator and compressor
An increase of air leakage from ductwork
Current in the compressor circuit

26. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An acid-core suction line drier
The sensing bulb at a lower temperature than the valve body
110-120

27. What is the purpose of the TXV...
A missing air filter+improper rotation of the indoor blower+blower too small
A plugged filter drier
It keeps a constant superheat in the evaporator
Low voltage and a faulty start relay

28. 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
A plugged filter drier
An uninsulated suction line and a restricted metering device
An uninsulated TXV sensing bulb
Both technicians are incorrect

29. 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...
Run with high head and high suction pressure
The sensing bulb at a lower temperature than the valve body
Short cycling and insufficient dehumidification
Low voltage and a faulty start relay

30. 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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31. 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...
Low superheat
It keeps a constant superheat in the evaporator
A plugged filter drier
A blown fuse

32. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Both technicians are correct
The discharge pressure increases and the amperage increases

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 internal overload is opened
Both technicians are incorrect
A vacuum test+oil traces around fittings+soap bubble solution

34. 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
Short cycling and insufficient dehumidification
Technician B
Low voltage and a faulty start relay
An uninsulated suction line and a restricted metering device

35. 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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36. Which of the following is a possible cause for a compressor to overheat...
It would cause the low-side pressure to decrease
The superheat increases and the subcooling decreases
A vacuum test+oil traces around fittings+soap bubble solution
A low refrigerant charge

37. 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
Technician B
The external equalizer could be plugged
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

38. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
High superheat and low discharge pressure
Run with high head and high suction pressure
Both technicians are incorrect
An uninsulated suction line and a restricted metering device

39. 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
Broken rings+broken valves+seized bearings
It would cause the low-side pressure to decrease
Technician B
An increase in low-side pressure

40. What is the purpose of a CPR valve...
Current in the compressor circuit
Low voltage and a faulty start relay
It is used to control refrigerant pressure in the compressor crankcase
('Y' and 'C') and ('G' and 'C')

41. Insufficient airflow can be caused by...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An acid-core suction line drier
Run with high head and high suction pressure
An increase of air leakage from ductwork

42. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
The superheat will increase and the low-side pressure will decrease
A bad thermostat
Condenser fans operating during a low ambient condition and a low suction pressure

43. What type of problems can be caused by an oversized air conditioning system...
Technician B
20 to 30
A defective circuit breaker
Short cycling and insufficient dehumidification

44. What problem or problems can cause low discharge and suction pressure...
The superheat increases and the subcooling decreases
An undercharged system+insufficient airflow over the evaporator coil
A low refrigerant charge
An acid-core suction line drier

45. When using a vapor-charged TXV bulb - it is necessary to have...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The system has been overcharged+The system has air trapped in the condenser
The sensing bulb at a lower temperature than the valve body
Dirty condenser - bent condenser fins - and air recirculating over the condenser

46. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Lack of airflow
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

47. A commercial customer calls on a 90
An acid-core suction line drier
20 to 30
A missing air filter+improper rotation of the indoor blower+blower too small
The system has been overcharged+The system has air trapped in the condenser

48. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A plugged filter drier
An overcharged system
The sight glass is full of liquid+the sight glass is full of gas
It would cause the low-side pressure to decrease

49. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It would cause the low-side pressure to decrease
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B

50. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The superheat will increase and the low-side pressure will decrease