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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. 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

2. Insufficient airflow can be caused by...
Rise more than normal
An increase of air leakage from ductwork
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

3. A compressor having tight bearings would cause the current value to...
An overcharged system
An increase in low-side pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Rise more than normal

4. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
It is used to control refrigerant pressure in the compressor crankcase
Bad compressor valve
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Whenever necessary

5. Which of the following will cause excessive discharge pressures on an air conditioning system...
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
3 psig
A bad thermostat

6. The internal overload of an air conditioning compressor senses winding temperature and...
The external equalizer could be plugged
The oil pump pressure and the crankcase pressure
Run with high head and high suction pressure
Current in the compressor circuit

7. What is the purpose of the TXV...
An uninsulated TXV sensing bulb
A blown fuse
An acid-core suction line drier
It keeps a constant superheat in the evaporator

8. When using a vapor-charged TXV bulb - it is necessary to have...
An acid-core suction line drier
Both technicians are correct
The sensing bulb at a lower temperature than the valve body
An overcharged system

9. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
An uninsulated suction line and a restricted metering device
A sensing bulb improperly connected to the suction line
20 to 30

10. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A vacuum test+oil traces around fittings+soap bubble solution
An acid-core suction line drier
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The sensing bulb at a lower temperature than the valve body

11. 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
The external equalizer could be plugged
The low-side pressure will decrease and the evaporator coil will be partially frosted
A restricted metering device
A defective circuit breaker

12. What causes the automatic expansion valve to close...
Contains a solenoid coil and one or more sets of contacts
The low-side pressure will decrease and the evaporator coil will be partially frosted
110-120
An increase in low-side pressure

13. 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
An acid-core suction line drier
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician A
20 to 30

14. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Technician B
A low refrigerant charge
An overcharged system
It keeps a constant superheat in the evaporator

15. What is the purpose of a CPR valve...
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 is used to control refrigerant pressure in the compressor crankcase
Evaporator and compressor

16. A hard-start kit consists of...
3 psig
A vacuum test+oil traces around fittings+soap bubble solution
An acid-core suction line drier
A start capacitor and a solid-state relay

17. 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
High superheat and low discharge pressure
Low superheat

18. Superheat is found in an air conditioning system in the...
Technician B
Evaporator and compressor
A sensing bulb improperly connected to the suction line
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

19. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
An overcharged system
An increase in suction pressure and an increase in discharge pressure
Current in the compressor circuit

20. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The internal overload is opened
A plugged filter drier
A bad thermostat
20 to 30

21. The internal overload of an air conditioning compressor senses winding temperature and...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Current in the compressor circuit
3 psig
The system has been overcharged+The system has air trapped in the condenser

22. What are the symptoms of a TXV air conditioning system if it has lost its charge...
A bad thermostat
Always have some liquid present in the bulb and diaphragm
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The superheat will increase and the low-side pressure will decrease

23. 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
Both technicians are correct
High suction pressure and low superheat
The oil pump pressure and the crankcase pressure

24. 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 dirty condenser - recirculation of condenser air - and a defective condenser fan
High suction pressure and low superheat
Technician A is correct
Broken rings+broken valves+seized bearings

25. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Low discharge pressure - high suction pressure - and low amp draw
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
An acid-core suction line drier

26. 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
The external equalizer could be plugged
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The system has been overcharged+The system has air trapped in the condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted

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
Technician B
Both technicians are incorrect
Broken rings+broken valves+seized bearings
The discharge pressure increases and the amperage increases

28. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
An acid-core suction line drier
A sensing bulb improperly connected to the suction line
Low superheat
It would cause the low-side pressure to decrease

29. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
The sensing bulb at a lower temperature than the valve body
Broken rings+broken valves+seized bearings
'G' to 'C'
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

30. 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
Low discharge pressure - high suction pressure - and low amp draw
Technician A
An overcharged system
A bad thermostat

31. 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
Low discharge pressure - high suction pressure - and low amp draw
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are correct
('Y' and 'C') and ('G' and 'C')

32. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The external equalizer could be plugged
A blown fuse
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
20 to 30

33. 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
Clean the condenser coil
A sensing bulb improperly connected to the suction line
An overcharged system
An undercharged system+insufficient airflow over the evaporator coil

34. 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 discharge pressure increases and the amperage increases
Condenser fans operating during a low ambient condition and a low suction pressure
Low discharge pressure - high suction pressure - and low amp draw
Technician B

35. What are the operating pressures of an oil pressure safety switch...
A restricted metering device
The oil pump pressure and the crankcase pressure
Increases starting torque
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

36. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An uninsulated TXV sensing bulb
An undercharge and low ambient conditions
An acid-core suction line drier
The oil pump pressure and the crankcase pressure

37. 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...
The internal overload is opened
Low discharge pressure - high suction pressure - and low amp draw
Technician B
An increase in low-side pressure

38. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Lack of airflow
20 to 30

39. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Both technicians are correct
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A sensing bulb improperly connected to the suction line
110-120

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
110-120
Clean the condenser coil
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B

41. A hard-start kit for an air conditioning system...
Contains a solenoid coil and one or more sets of contacts
The discharge pressure increases and the amperage increases
Increases starting torque
Low discharge pressure - high suction pressure - and low amp draw

42. A hard-start kit consists of...
A start capacitor and a solid-state relay
Technician B
An overcharged system
It would cause the low-side pressure to decrease

43. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Technician A is correct
Technician B
An overcharged system
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

44. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
A start relay
50-65
A bad thermostat

45. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
'G' to 'C'
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The system has been overcharged+The system has air trapped in the condenser
Technician B

46. Which of the following is a possible cause for a compressor to overheat...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An increase in suction pressure and an increase in discharge pressure
A low refrigerant charge
An acid-core suction line drier

47. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are correct
Clean the condenser coil
The sight glass is full of liquid+the sight glass is full of gas

48. What type of problems can be caused by an oversized air conditioning system...
Clean the condenser coil
Short cycling and insufficient dehumidification
Current in the compressor circuit
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

49. 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 defective circuit breaker
Technician B
The superheat increases and the subcooling decreases
3 psig

50. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
An uninsulated suction line and a restricted metering device
The internal overload is opened
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication