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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 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
It is used to control refrigerant pressure in the compressor crankcase
Dirty condenser - bent condenser fins - and air recirculating over the condenser
50-65
Technician B

2. What are the symptoms of an air conditioning system that has a low charge...
It is used to control refrigerant pressure in the compressor crankcase
Rise more than normal
The low-side pressure will decrease and the evaporator coil will be partially frosted
Partially frosted evaporator and high superheat

3. Why is it unsafe to operate an air conditioning system with a low charge...
Flooding the condenser - cycling condenser fans - and dampering condenser air
110-120
Lack of airflow
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

4. What are common methods that are used for leak-testing a system...
Evaporator and compressor
Both technicians are incorrect
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A vacuum test+oil traces around fittings+soap bubble solution

5. When using a vapor-charged TXV bulb - it is necessary to have...
Condenser fans operating during a low ambient condition and a low suction pressure
The sensing bulb at a lower temperature than the valve body
Partially frosted evaporator and high superheat
Low voltage and a faulty start relay

6. 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
It is used to control refrigerant pressure in the compressor crankcase
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B

7. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
It keeps a constant superheat in the evaporator
Low superheat
Technician B

8. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The sight glass is full of liquid+the sight glass is full of gas
A restricted metering device
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

9. 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
50-65
Always have some liquid present in the bulb and diaphragm
It keeps a constant superheat in the evaporator

10. Which of the following can cause excessive subcooling...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An open internal overload protector
An overcharged system
Both technicians are correct

11. Which of the following could be the cause for a system's discharge and suction pressure being low...
Both technicians are correct
A restricted metering device
An uninsulated suction line and a restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

12. 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
The external equalizer could be plugged
Contains a solenoid coil and one or more sets of contacts
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

13. What is the purpose of a CPR valve...
Low discharge pressure - high suction pressure - and low amp draw
Technician B
It is used to control refrigerant pressure in the compressor crankcase
Technician B

14. 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
Both technicians are incorrect
A vacuum test+oil traces around fittings+soap bubble solution
Clean the condenser coil
It would cause the low-side pressure to decrease

15. A system that uses a thermal electric expansion valve...
The system has been overcharged+The system has air trapped in the condenser
An open internal overload protector
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B

16. A hard-start kit consists of...
Technician A is correct
Low superheat
A start capacitor and a solid-state relay
Low voltage and a faulty start relay

17. 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
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
Contains a solenoid coil and one or more sets of contacts

18. What is the common cause of a compressor burnout...
A sensing bulb improperly connected to the suction line
Both technicians are correct
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Evaporator and compressor

19. 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
The low-side pressure will decrease and the evaporator coil will be partially frosted
A restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B

20. What are the symptoms of an air conditioning system that has a low charge...
The sensing bulb at a lower temperature than the valve body
Clean the condenser coil
It would cause the low-side pressure to decrease
The low-side pressure will decrease and the evaporator coil will be partially frosted

21. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
The sight glass is full of liquid+the sight glass is full of gas
Flooding the condenser - cycling condenser fans - and dampering condenser air
High superheat and low discharge pressure
A plugged filter drier

22. Which of the following is a possible cause for a compressor to overheat...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A bad thermostat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A low refrigerant charge

23. What three things can prevent an air conditioning system from releasing heat at the proper rate...
3 psig
110-120
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

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
The sight glass is full of liquid+the sight glass is full of gas
Broken rings+broken valves+seized bearings
Current in the compressor circuit
The internal overload is opened

25. 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
An increase in suction pressure and an increase in discharge pressure
The superheat will increase and the low-side pressure will decrease
Technician B
An increase of air leakage from ductwork

26. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Both technicians are incorrect
The superheat will increase and the low-side pressure will decrease
A low refrigerant charge
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

27. What type of problems can be caused by an oversized air conditioning system...
The discharge pressure increases and the amperage increases
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
Short cycling and insufficient dehumidification

28. What is the purpose of the TXV...
Current in the compressor circuit
It keeps a constant superheat in the evaporator
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

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...
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
High superheat and low discharge pressure
It is used to control refrigerant pressure in the compressor crankcase

30. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
The discharge pressure increases and the amperage increases
Run with high head and high suction pressure
An overcharged system

31. 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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32. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
An open internal overload protector
The superheat will increase and the low-side pressure will decrease
High superheat and low discharge pressure

33. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician A is correct
It keeps a constant superheat in the evaporator

34. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A missing air filter+improper rotation of the indoor blower+blower too small
Run with high head and high suction pressure
High suction pressure and low superheat
An increase in suction pressure and an increase in discharge pressure

35. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
20 to 30
Technician B
An increase of air leakage from ductwork

36. What causes the automatic expansion valve to close...
Increases starting torque
Rise more than normal
A bad thermostat
An increase in low-side pressure

37. Which of the following will cause excessive discharge pressures on an air conditioning system...
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
Bad compressor valve
A restricted metering device

38. A system that is operating with a clear sight glass shows...
Contains a solenoid coil and one or more sets of contacts
The sight glass is full of liquid+the sight glass is full of gas
It keeps a constant superheat in the evaporator
A sensing bulb improperly connected to the suction line

39. A restricted air filter in an air conditioning system can be identified by...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The oil pump pressure and the crankcase pressure
Low superheat

40. A customer calls to complain that his central air conditioning system is not cooling properly. The technician arrives on the job. He or she notices that the indoor blower has adequate airflow and the outdoor condenser fan is operating - but the compr
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
High suction pressure and low superheat
A plugged filter drier
An open internal overload protector

41. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
An increase of air leakage from ductwork
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

42. What problem or problems can cause low discharge and suction pressure...
Low superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An undercharged system+insufficient airflow over the evaporator coil
An uninsulated suction line and a restricted metering device

43. 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
It keeps a constant superheat in the evaporator
Broken rings+broken valves+seized bearings
An uninsulated suction line and a restricted metering device
Technician B

44. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Technician B
Technician B
('Y' and 'C') and ('G' and 'C')
An undercharge and low ambient conditions

45. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
3 psig
Both technicians are incorrect
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It is used to control refrigerant pressure in the compressor crankcase

46. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Always have some liquid present in the bulb and diaphragm
The sight glass is full of liquid+the sight glass is full of gas

47. Air filters should be replaced...
Technician B
An uninsulated TXV sensing bulb
Partially frosted evaporator and high superheat
Whenever necessary

48. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A restricted metering device
The external equalizer could be plugged

49. 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
110-120
Technician A is correct
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

50. Which of the following is a possible cause for a compressor to overheat...
High superheat and low discharge pressure
The superheat increases and the subcooling decreases
A low refrigerant charge
An uninsulated TXV sensing bulb