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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. Air filters should be replaced...
Whenever necessary
A defective circuit breaker
The system has been overcharged+The system has air trapped in the condenser
Bad compressor valve

2. Why is it unsafe to operate an air conditioning system with a low charge...
110-120
Clean the condenser coil
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

3. A customer calls and says that her air conditioning system is not cooling properly. Upon arrival - a technician notices that the suction line and compressor have frost buildup. Technician A says that the problem is probably a low charge. Technician B
Clean the condenser coil
Technician B
Run with high head and high suction pressure
Low superheat

4. What are two common symptoms of refrigerant leaks in an air conditioning system...
3 psig
Partially frosted evaporator and high superheat
A defective circuit breaker
'G' to 'C'

5. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
110-120
An uninsulated TXV sensing bulb
A plugged filter drier
50-65

6. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
High superheat and low discharge pressure
It would cause the low-side pressure to decrease
Low superheat
A vacuum test+oil traces around fittings+soap bubble solution

7. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Both technicians are correct
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Partially frosted evaporator and high superheat
20 to 30

8. A commercial customer calls on a 90
An acid-core suction line drier
The system has been overcharged+The system has air trapped in the condenser
An open internal overload protector
A restricted metering device

9. What is the common cause of a compressor burnout...
Technician B
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An overcharged system

10. What problem can cause an increase of discharge pressure and an increase of suction pressure...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An overcharged system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A bad thermostat

11. 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
Broken rings+broken valves+seized bearings
The discharge pressure increases and the amperage increases
Flooding the condenser - cycling condenser fans - and dampering condenser air
The low-side pressure will decrease and the evaporator coil will be partially frosted

12. The best description of a relay would be...
Technician B
Technician B
'G' to 'C'
Contains a solenoid coil and one or more sets of contacts

13. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
A defective circuit breaker
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
Dirty condenser - bent condenser fins - and air recirculating over the condenser

14. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
Both technicians are incorrect
Dirty condenser - bent condenser fins - and air recirculating over the condenser
'G' to 'C'

15. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
High superheat and low discharge pressure
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air

16. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
A plugged filter drier
Bad compressor valve
A sensing bulb improperly connected to the suction line

17. 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
High suction pressure and low superheat
An uninsulated suction line and a restricted metering device
Clean the condenser coil
It keeps a constant superheat in the evaporator

18. A commercial customer calls on a 90
An overcharged system
The system has been overcharged+The system has air trapped in the condenser
Technician B
Partially frosted evaporator and high superheat

19. 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
Increases starting torque
Technician A
A restricted metering device
Technician B

20. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
An acid-core suction line drier
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

21. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Rise more than normal
The superheat increases and the subcooling decreases
Partially frosted evaporator and high superheat
Clean the condenser coil

22. What is the purpose of an EPR valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Lack of airflow
A blown fuse
It keeps a constant superheat in the evaporator

23. What causes the automatic expansion valve to close...
Technician A is correct
An increase in low-side pressure
It would cause the low-side pressure to decrease
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

24. What component is most often the cause of a start capacitor failure...
A start relay
Contains a solenoid coil and one or more sets of contacts
Low voltage and a faulty start relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

25. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The superheat will increase and the low-side pressure will decrease
It keeps a constant superheat in the evaporator
Technician A
An uninsulated suction line and a restricted metering device

26. 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
('Y' and 'C') and ('G' and 'C')
Both technicians are incorrect
An undercharged system+insufficient airflow over the evaporator coil
The internal overload is opened

27. 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
50-65
110-120
A plugged filter drier
Technician A

28. A system that is operating with a clear sight glass shows...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The sight glass is full of liquid+the sight glass is full of gas
Lack of airflow
Both technicians are incorrect

29. 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
A start relay
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

30. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Rise more than normal
Low discharge pressure - high suction pressure - and low amp draw
3 psig
Low voltage and a faulty start relay

31. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
Both technicians are correct
Bad compressor valve
Whenever necessary

32. A hard-start kit for an air conditioning system...
Increases starting torque
It is used to control refrigerant pressure in the compressor crankcase
Partially frosted evaporator and high superheat
Current in the compressor circuit

33. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Contains a solenoid coil and one or more sets of contacts
High suction pressure and low superheat
Partially frosted evaporator and high superheat
A start capacitor and a solid-state relay

34. Superheat is found in an air conditioning system in the...
Evaporator and compressor
The superheat increases and the subcooling decreases
A missing air filter+improper rotation of the indoor blower+blower too small
3 psig

35. 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...
Broken rings+broken valves+seized bearings
An open internal overload protector
A blown fuse
Short cycling and insufficient dehumidification

36. 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...
Both technicians are incorrect
The internal overload is opened
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A sensing bulb improperly connected to the suction line

37. A hard-start kit consists of...
The discharge pressure increases and the amperage increases
A start capacitor and a solid-state relay
Short cycling and insufficient dehumidification
Low discharge pressure - high suction pressure - and low amp draw

38. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Rise more than normal
An overcharged system
Technician B
An acid-core suction line drier

39. 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
The internal overload is opened
A start capacitor and a solid-state relay
A sensing bulb improperly connected to the suction line

40. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Clean the condenser coil
Technician B
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

41. 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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42. Which of the following is a possible cause for a compressor to overheat...
A blown fuse
An undercharge and low ambient conditions
A low refrigerant charge
A start relay

43. A customer calls and says that her air conditioning system is not cooling properly. Upon arrival - a technician notices that the suction line and compressor have frost buildup. Technician A says that the problem is probably a low charge. Technician B
Technician B
Low superheat
An uninsulated TXV sensing bulb
Low voltage and a faulty start relay

44. What causes the automatic expansion valve to close...
An increase in low-side pressure
An overcharged system
Run with high head and high suction pressure
Technician B

45. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A missing air filter+improper rotation of the indoor blower+blower too small
110-120
Flooding the condenser - cycling condenser fans - and dampering condenser air
The internal overload is opened

46. 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
A defective circuit breaker
The discharge pressure increases and the amperage increases
Technician B
Always have some liquid present in the bulb and diaphragm

47. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An increase of air leakage from ductwork
Both technicians are incorrect
An acid-core suction line drier

48. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
50-65
The external equalizer could be plugged

49. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
50-65
The sight glass is full of liquid+the sight glass is full of gas
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

50. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An uninsulated TXV sensing bulb
The discharge pressure increases and the amperage increases
Evaporator and compressor
The internal overload is opened