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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 causes the automatic expansion valve to close...
Technician B
Technician B
An increase in low-side pressure
Increases starting torque

2. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A start capacitor and a solid-state relay
Technician A

3. 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
Short cycling and insufficient dehumidification
A plugged filter drier
The sensing bulb at a lower temperature than the valve body

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...
It is used to control refrigerant pressure in the compressor crankcase
20 to 30
An overcharged system
Low voltage and a faulty start relay

5. 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
A sensing bulb improperly connected to the suction line
A restricted metering device
The superheat increases and the subcooling decreases

6. 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
Technician A
The superheat will increase and the low-side pressure will decrease
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B

7. 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
It would cause the low-side pressure to decrease
An uninsulated TXV sensing bulb
Dirty condenser - bent condenser fins - and air recirculating over the condenser

8. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A dirty condenser - recirculation of condenser air - and a defective condenser fan

9. 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
Rise more than normal
Contains a solenoid coil and one or more sets of contacts
Technician A is correct
The discharge pressure increases and the amperage increases

10. The temperature range of the suction line from an air conditioning system should be...
50-65
The external equalizer could be plugged
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B

11. What are common methods that are used for leak-testing a system...
The system has been overcharged+The system has air trapped in the condenser
A start relay
A vacuum test+oil traces around fittings+soap bubble solution
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

12. 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...
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
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

13. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Whenever necessary
A missing air filter+improper rotation of the indoor blower+blower too small
Dirty condenser - bent condenser fins - and air recirculating over the condenser

14. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The discharge pressure increases and the amperage increases
Technician B
An uninsulated suction line and a restricted metering device

15. What component is most often the cause of a start capacitor failure...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
High suction pressure and low superheat
A start relay

16. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Low voltage and a faulty start relay
Increases starting torque
An uninsulated suction line and a restricted metering device
An increase of air leakage from ductwork

17. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Short cycling and insufficient dehumidification
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An acid-core suction line drier
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

18. A commercial customer calls on a 90
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Short cycling and insufficient dehumidification
The system has been overcharged+The system has air trapped in the condenser
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

19. 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
A sensing bulb improperly connected to the suction line
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

20. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
It is used to control refrigerant pressure in the compressor crankcase
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An undercharge and low ambient conditions
The sensing bulb at a lower temperature than the valve body

21. 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...
110-120
An increase of air leakage from ductwork
An overcharged system
Condenser fans operating during a low ambient condition and a low suction pressure

22. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Technician B
A blown fuse
Clean the condenser coil
An increase in suction pressure and an increase in discharge pressure

23. What are two problems that can cause an air conditioning system to have an excessively high superheat...
The internal overload is opened
Both technicians are incorrect
Always have some liquid present in the bulb and diaphragm
An uninsulated suction line and a restricted metering device

24. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Contains a solenoid coil and one or more sets of contacts
Short cycling and insufficient dehumidification
Rise more than normal
A missing air filter+improper rotation of the indoor blower+blower too small

25. The internal overload of an air conditioning compressor senses winding temperature and...
Both technicians are incorrect
Current in the compressor circuit
The sight glass is full of liquid+the sight glass is full of gas
Low discharge pressure - high suction pressure - and low amp draw

26. Which of the following can cause excessive subcooling...
Rise more than normal
An overcharged system
Rise more than normal
The oil pump pressure and the crankcase pressure

27. 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
Technician B
An uninsulated TXV sensing bulb
An increase of air leakage from ductwork
An overcharged system

28. 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 open internal overload protector
Technician B
Both technicians are correct
The external equalizer could be plugged

29. 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 start relay
The system has been overcharged+The system has air trapped in the condenser
Low voltage and a faulty start relay
High superheat and low discharge pressure

30. 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
High suction pressure and low superheat
The sight glass is full of liquid+the sight glass is full of gas
Partially frosted evaporator and high superheat

31. 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 increase in suction pressure and an increase in discharge pressure
Broken rings+broken valves+seized bearings
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

32. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An overcharged system

33. 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 dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It is used to control refrigerant pressure in the compressor crankcase
It would cause the low-side pressure to decrease
Both technicians are incorrect

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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B
110-120
The superheat will increase and the low-side pressure will decrease

35. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Low discharge pressure - high suction pressure - and low amp draw
A restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Run with high head and high suction pressure

36. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Low discharge pressure - high suction pressure - and low amp draw
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
'G' to 'C'
An increase in suction pressure and an increase in discharge pressure

37. 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
An uninsulated suction line and a restricted metering device
Both technicians are correct
A restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

38. 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...
The sensing bulb at a lower temperature than the valve body
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A blown fuse
The sight glass is full of liquid+the sight glass is full of gas

39. A 220-volt 30-amp motor circuit keeps tripping the breaker after the motor is started. The starting amperage is 60 amps. When measuring the amperage of the circuit - This is drawn for a brief moment. After startup - the amperage drops to 22 amps and
Technician A
3 psig
Technician B
A defective circuit breaker

40. 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
Both technicians are incorrect
Technician A is correct
Both technicians are incorrect

41. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An overcharged system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

42. A hard-start kit for an air conditioning system...
An uninsulated TXV sensing bulb
The internal overload is opened
Increases starting torque
High superheat and low discharge pressure

43. 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...
Clean the condenser coil
'G' to 'C'
The internal overload is opened
Technician B

44. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
110-120
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A start capacitor and a solid-state relay
Lack of airflow

45. What problem or problems can cause low discharge and suction pressure...
The sight glass is full of liquid+the sight glass is full of gas
Lack of airflow
An undercharged system+insufficient airflow over the evaporator coil
Bad compressor valve

46. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
110-120
Increases starting torque
It would cause the low-side pressure to decrease
Technician A is correct

47. Which of the following could be the cause for a system's discharge and suction pressure being low...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Condenser fans operating during a low ambient condition and a low suction pressure
A restricted metering device
A defective circuit breaker

48. 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 plugged filter drier
Bad compressor valve
The superheat will increase and the low-side pressure will decrease

49. Superheat is found in an air conditioning system in the...
A defective circuit breaker
Evaporator and compressor
Increases starting torque
Both technicians are incorrect

50. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A start capacitor and a solid-state relay
An increase of air leakage from ductwork
Lack of airflow
An increase in suction pressure and an increase in discharge pressure