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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. 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
Technician A is correct
It would cause the low-side pressure to decrease
The discharge pressure increases and the amperage increases
Low voltage and a faulty start relay

2. 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...
Broken rings+broken valves+seized bearings
Low voltage and a faulty start relay
Both technicians are incorrect
Contains a solenoid coil and one or more sets of contacts

3. A customer calls with an insufficient cooling complaint on a 90
Technician B
The oil pump pressure and the crankcase pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
An increase in suction pressure and an increase in discharge pressure

4. 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 acid-core suction line drier
An acid-core suction line drier
Technician A is correct
Technician B

5. Which of the following is a possible cause for a compressor to overheat...
A defective circuit breaker
High superheat and low discharge pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A low refrigerant charge

6. 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
Rise more than normal
A restricted metering device
An open internal overload protector

7. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
An acid-core suction line drier
Low superheat
An increase of air leakage from ductwork

8. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A restricted metering device
A start capacitor and a solid-state relay
It would cause the low-side pressure to decrease
An acid-core suction line drier

9. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Both technicians are incorrect
An increase in suction pressure and an increase in discharge pressure
A low refrigerant charge
20 to 30

10. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Partially frosted evaporator and high superheat
Bad compressor valve
A bad thermostat
High suction pressure and low superheat

11. A commercial customer calls on a 90
The oil pump pressure and the crankcase pressure
The system has been overcharged+The system has air trapped in the condenser
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician A is correct

12. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician A
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An undercharge and low ambient conditions
An increase in suction pressure and an increase in discharge pressure

13. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
An overcharged system
The internal overload is opened
An undercharged system+insufficient airflow over the evaporator coil

14. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Rise more than normal
110-120
The discharge pressure increases and the amperage increases
A blown fuse

15. Air filters should be replaced...
Whenever necessary
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
('Y' and 'C') and ('G' and 'C')

16. Superheat is found in an air conditioning system in the...
Evaporator and compressor
The sight glass is full of liquid+the sight glass is full of gas
The sensing bulb at a lower temperature than the valve body
The external equalizer could be plugged

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...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A start capacitor and a solid-state relay
An acid-core suction line drier
An uninsulated suction line and a restricted metering device

18. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Low discharge pressure - high suction pressure - and low amp draw
Technician A
A start relay
It keeps a constant superheat in the evaporator

19. What is the purpose of an EPR valve...
An increase in low-side pressure
50-65
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Always have some liquid present in the bulb and diaphragm

20. Insufficient airflow can be caused by...
Technician B
An increase of air leakage from ductwork
A start capacitor and a solid-state relay
Technician B

21. A liquid-charged TXV bulb will...
The sight glass is full of liquid+the sight glass is full of gas
Technician B
Always have some liquid present in the bulb and diaphragm
Technician B

22. What type of problems can be caused by an oversized air conditioning system...
An uninsulated TXV sensing bulb
The low-side pressure will decrease and the evaporator coil will be partially frosted
Short cycling and insufficient dehumidification
It would cause the low-side pressure to decrease

23. 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
Whenever necessary
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A start capacitor and a solid-state relay
The external equalizer could be plugged

24. 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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25. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The superheat increases and the subcooling decreases
Technician A is correct
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Bad compressor valve

26. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
The superheat increases and the subcooling decreases
Dirty condenser - bent condenser fins - and air recirculating over the condenser
3 psig
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

27. 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...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Bad compressor valve
Condenser fans operating during a low ambient condition and a low suction pressure
50-65

28. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Low voltage and a faulty start relay
3 psig
The system has been overcharged+The system has air trapped in the condenser
An increase in suction pressure and an increase in discharge pressure

29. A system that uses a thermal electric expansion valve...
The internal overload is opened
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
A start capacitor and a solid-state relay

30. 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
Technician A
Technician B
A sensing bulb improperly connected to the suction line

31. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
An overcharged system
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A missing air filter+improper rotation of the indoor blower+blower too small

32. 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
The internal overload is opened
Technician B
It keeps a constant superheat in the evaporator
The discharge pressure increases and the amperage increases

33. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Broken rings+broken valves+seized bearings
The sensing bulb at a lower temperature than the valve body
An increase of air leakage from ductwork
Low discharge pressure - high suction pressure - and low amp draw

34. Which of the following could be the cause for a system's discharge and suction pressure being low...
The internal overload is opened
Broken rings+broken valves+seized bearings
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A restricted metering device

35. A commercial customer calls on a 90
An increase in low-side pressure
Current in the compressor circuit
The system has been overcharged+The system has air trapped in the condenser
3 psig

36. 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
A defective circuit breaker
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Broken rings+broken valves+seized bearings
High superheat and low discharge pressure

37. 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
3 psig
The low-side pressure will decrease and the evaporator coil will be partially frosted
Broken rings+broken valves+seized bearings

38. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Flooding the condenser - cycling condenser fans - and dampering condenser air
High suction pressure and low superheat
A bad thermostat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

39. 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
Whenever necessary
Both technicians are incorrect
An acid-core suction line drier
A missing air filter+improper rotation of the indoor blower+blower too small

40. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Technician B
An undercharge and low ambient conditions
A vacuum test+oil traces around fittings+soap bubble solution
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

41. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Low discharge pressure - high suction pressure - and low amp draw
Lack of airflow
Technician B
Technician B

42. What are two common symptoms of refrigerant leaks in an air conditioning system...
An acid-core suction line drier
Partially frosted evaporator and high superheat
Condenser fans operating during a low ambient condition and a low suction pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

43. 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
20 to 30
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
Clean the condenser coil

44. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are incorrect

45. Air filters should be replaced...
An undercharged system+insufficient airflow over the evaporator coil
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An overcharged system
Whenever necessary

46. 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 start capacitor and a solid-state relay
A vacuum test+oil traces around fittings+soap bubble solution
A low refrigerant charge
Technician B

47. Which of the following can cause low superheat in a TXV system...
It is used to control refrigerant pressure in the compressor crankcase
An uninsulated TXV sensing bulb
An uninsulated suction line and a restricted metering device
'G' to 'C'

48. A customer calls with an insufficient cooling complaint on a 90
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A plugged filter drier
A start capacitor and a solid-state relay
Technician B

49. Why is it unsafe to operate an air conditioning system with a low charge...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A start relay
An uninsulated suction line and a restricted metering device
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

50. 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
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
Both technicians are correct
Lack of airflow