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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 ' 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 dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
Low voltage and a faulty start relay

2. 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
Short cycling and insufficient dehumidification
An increase of air leakage from ductwork
Whenever necessary
Both technicians are incorrect

3. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A missing air filter+improper rotation of the indoor blower+blower too small
An overcharged system

4. 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
An open internal overload protector
Technician B
3 psig
A dirty condenser - recirculation of condenser air - and a defective condenser fan

5. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
An overcharged system
Technician B
An increase in low-side pressure

6. Superheat is found in an air conditioning system in the...
A start relay
Evaporator and compressor
It would cause the low-side pressure to decrease
The low-side pressure will decrease and the evaporator coil will be partially frosted

7. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated TXV sensing bulb
An uninsulated suction line and a restricted metering device
An acid-core suction line drier
The superheat will increase and the low-side pressure will decrease

8. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
The discharge pressure increases and the amperage increases
A defective circuit breaker
An undercharge and low ambient conditions
A plugged filter drier

9. 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
It would cause the low-side pressure to decrease
A low refrigerant charge
The oil pump pressure and the crankcase pressure
Technician B

10. What type of problems can be caused by an oversized air conditioning system...
Condenser fans operating during a low ambient condition and a low suction pressure
It keeps a constant superheat in the evaporator
Short cycling and insufficient dehumidification
Technician B

11. Air filters should be replaced...
Whenever necessary
An uninsulated TXV sensing bulb
An acid-core suction line drier
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

12. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An overcharged system
Run with high head and high suction pressure
Both technicians are correct

13. 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
Current in the compressor circuit
It keeps a constant superheat in the evaporator
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

14. What are three methods for controlling a system's high-side pressure during low ambient conditions...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A vacuum test+oil traces around fittings+soap bubble solution
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B

15. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Contains a solenoid coil and one or more sets of contacts
Low discharge pressure - high suction pressure - and low amp draw
An acid-core suction line drier
Both technicians are correct

16. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
The internal overload is opened
Run with high head and high suction pressure
It keeps a constant superheat in the evaporator
Technician B

17. The temperature range of the suction line from an air conditioning system should be...
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
Bad compressor valve
50-65

18. 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
It would cause the low-side pressure to decrease
Technician B
The oil pump pressure and the crankcase pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser

19. A hard-start kit consists of...
Flooding the condenser - cycling condenser fans - and dampering condenser air
The internal overload is opened
A start capacitor and a solid-state relay
Current in the compressor circuit

20. 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
It is used to control refrigerant pressure in the compressor crankcase
Technician A is correct
Both technicians are incorrect
High superheat and low discharge pressure

21. 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
The superheat will increase and the low-side pressure will decrease
Run with high head and high suction pressure
Rise more than normal

22. 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

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23. 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
An undercharge and low ambient conditions
It keeps a constant superheat in the evaporator
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

24. Which of the following can cause excessive subcooling...
The system has been overcharged+The system has air trapped in the condenser
Bad compressor valve
Both technicians are incorrect
An overcharged system

25. 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
Lack of airflow
Short cycling and insufficient dehumidification
Technician A is correct
A bad thermostat

26. A compressor having tight bearings would cause the current value to...
A low refrigerant charge
Rise more than normal
Lack of airflow
The low-side pressure will decrease and the evaporator coil will be partially frosted

27. A customer calls with an insufficient cooling complaint on a 90
A sensing bulb improperly connected to the suction line
3 psig
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B

28. A system that is operating with a clear sight glass shows...
Low superheat
Low superheat
The sight glass is full of liquid+the sight glass is full of gas
An acid-core suction line drier

29. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A plugged filter drier
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B

30. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Low superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An undercharge and low ambient conditions
An undercharged system+insufficient airflow over the evaporator coil

31. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Low superheat
An undercharge and low ambient conditions
It is used to control refrigerant pressure in the compressor crankcase
A missing air filter+improper rotation of the indoor blower+blower too small

32. Which of the following can cause low superheat in a TXV system...
A sensing bulb improperly connected to the suction line
An undercharged system+insufficient airflow over the evaporator coil
The internal overload is opened
An uninsulated TXV sensing bulb

33. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
An undercharged system+insufficient airflow over the evaporator coil
An increase in low-side pressure
Technician A is correct

34. What are the symptoms of an air conditioning system that has a low charge...
An acid-core suction line drier
The low-side pressure will decrease and the evaporator coil will be partially frosted
('Y' and 'C') and ('G' and 'C')
It keeps a constant superheat in the evaporator

35. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
A blown fuse
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Run with high head and high suction pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

36. 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...
Low discharge pressure - high suction pressure - and low amp draw
An increase in suction pressure and an increase in discharge pressure
Clean the condenser coil
High superheat and low discharge pressure

37. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Partially frosted evaporator and high superheat
50-65
Technician B

38. When using a vapor-charged TXV bulb - it is necessary to have...
Low superheat
The sensing bulb at a lower temperature than the valve body
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B

39. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
An increase in suction pressure and an increase in discharge pressure
An uninsulated TXV sensing bulb
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A blown fuse

40. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
An acid-core suction line drier
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The low-side pressure will decrease and the evaporator coil will be partially frosted

41. 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...
A blown fuse
Clean the condenser coil
The oil pump pressure and the crankcase pressure
It is used to control refrigerant pressure in the compressor crankcase

42. What are two common symptoms of refrigerant leaks in an air conditioning system...
An uninsulated TXV sensing bulb
It would cause the low-side pressure to decrease
Evaporator and compressor
Partially frosted evaporator and high superheat

43. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Technician A
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Bad compressor valve

44. 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...
Rise more than normal
It is used to control refrigerant pressure in the compressor crankcase
An acid-core suction line drier
Condenser fans operating during a low ambient condition and a low suction pressure

45. 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
Clean the condenser coil
Technician B
Technician A

46. 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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47. Which of the following could be the cause for a system's discharge and suction pressure being low...
A blown fuse
An increase in low-side pressure
Always have some liquid present in the bulb and diaphragm
A restricted metering device

48. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Low voltage and a faulty start relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Evaporator and compressor
A missing air filter+improper rotation of the indoor blower+blower too small

49. A compressor having tight bearings would cause the current value to...
Run with high head and high suction pressure
Condenser fans operating during a low ambient condition and a low suction pressure
Rise more than normal
An acid-core suction line drier

50. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
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
50-65
Low discharge pressure - high suction pressure - and low amp draw