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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. 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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2. 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
Broken rings+broken valves+seized bearings
The sensing bulb at a lower temperature than the valve body
A vacuum test+oil traces around fittings+soap bubble solution

3. Air filters should be replaced...
Contains a solenoid coil and one or more sets of contacts
Whenever necessary
Run with high head and high suction pressure
Technician B

4. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
A restricted metering device
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B
A sensing bulb improperly connected to the suction line

5. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
The sensing bulb at a lower temperature than the valve body
The oil pump pressure and the crankcase pressure
It keeps a constant superheat in the evaporator
An acid-core suction line drier

6. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An increase of air leakage from ductwork
A missing air filter+improper rotation of the indoor blower+blower too small
Bad compressor valve
The system has been overcharged+The system has air trapped in the condenser

7. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
A plugged filter drier
An undercharged system+insufficient airflow over the evaporator coil
Rise more than normal

8. 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...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The external equalizer could be plugged
The internal overload is opened
It would cause the low-side pressure to decrease

9. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Whenever necessary
The sensing bulb at a lower temperature than the valve body
The sight glass is full of liquid+the sight glass is full of gas

10. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
3 psig
The sight glass is full of liquid+the sight glass is full of gas
Low superheat
High suction pressure and low superheat

11. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Whenever necessary
A plugged filter drier
Always have some liquid present in the bulb and diaphragm

12. A liquid-charged TXV bulb will...
An increase in suction pressure and an increase in discharge pressure
Always have some liquid present in the bulb and diaphragm
The superheat increases and the subcooling decreases
('Y' and 'C') and ('G' and 'C')

13. 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 is used to control refrigerant pressure in the compressor crankcase
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
Clean the condenser coil

14. 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
Lack of airflow
An increase of air leakage from ductwork
Partially frosted evaporator and high superheat

15. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Current in the compressor circuit
Technician B
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air

16. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Condenser fans operating during a low ambient condition and a low suction pressure
Lack of airflow
An uninsulated TXV sensing bulb
3 psig

17. The temperature range of the suction line from an air conditioning system should be...
50-65
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A bad thermostat
High suction pressure and low superheat

18. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Run with high head and high suction pressure
The superheat increases and the subcooling decreases
The discharge pressure increases and the amperage increases
Technician B

19. Superheat is found in an air conditioning system in the...
Evaporator and compressor
An increase in suction pressure and an increase in discharge pressure
Both technicians are correct
A blown fuse

20. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
An uninsulated suction line and a restricted metering device
It keeps a constant superheat in the evaporator
110-120
A plugged filter drier

21. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
Technician A is correct
Technician B
Whenever necessary

22. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Run with high head and high suction pressure
Run with high head and high suction pressure
Bad compressor valve
A bad thermostat

23. 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 plugged air filter+a bad indoor blower relay
Technician A is correct
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Clean the condenser coil

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
An increase in suction pressure and an increase in discharge pressure
The discharge pressure increases and the amperage increases
Broken rings+broken valves+seized bearings
The system has been overcharged+The system has air trapped in the condenser

25. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A sensing bulb improperly connected to the suction line
An increase in suction pressure and an increase in discharge pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An increase in suction pressure and an increase in discharge pressure

26. What is the purpose of a CPR valve...
Increases starting torque
Always have some liquid present in the bulb and diaphragm
It is used to control refrigerant pressure in the compressor crankcase
The system has been overcharged+The system has air trapped in the condenser

27. Superheat is found in an air conditioning system in the...
Low discharge pressure - high suction pressure - and low amp draw
High suction pressure and low superheat
An uninsulated TXV sensing bulb
Evaporator and compressor

28. 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 is used to control refrigerant pressure in the compressor crankcase
Technician B
The system has been overcharged+The system has air trapped in the condenser
Partially frosted evaporator and high superheat

29. 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
Run with high head and high suction pressure
Both technicians are incorrect
Bad compressor valve

30. 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
A bad thermostat
Rise more than normal
The external equalizer could be plugged

31. Which of the following is a common cause of an excessively low superheat on a TXV system...
Partially frosted evaporator and high superheat
The sight glass is full of liquid+the sight glass is full of gas
A missing air filter+improper rotation of the indoor blower+blower too small
A sensing bulb improperly connected to the suction line

32. A liquid-charged TXV bulb will...
The system has been overcharged+The system has air trapped in the condenser
Always have some liquid present in the bulb and diaphragm
An increase in suction pressure and an increase in discharge pressure
Technician A is correct

33. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Whenever necessary
The external equalizer could be plugged

34. What type of problems can be caused by an oversized air conditioning system...
High suction pressure and low superheat
Short cycling and insufficient dehumidification
Clean the condenser coil
The system has been overcharged+The system has air trapped in the condenser

35. 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
Technician A
Low voltage and a faulty start relay
Condenser fans operating during a low ambient condition and a low suction pressure
The external equalizer could be plugged

36. A compressor having tight bearings would cause the current value to...
Rise more than normal
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
('Y' and 'C') and ('G' and 'C')
An increase of air leakage from ductwork

37. The best description of a relay would be...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Low discharge pressure - high suction pressure - and low amp draw
Contains a solenoid coil and one or more sets of contacts
Both technicians are correct

38. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The superheat will increase and the low-side pressure will decrease
It keeps a constant superheat in the evaporator
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An undercharged system+insufficient airflow over the evaporator coil

39. 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 superheat increases and the subcooling decreases
The superheat will increase and the low-side pressure will decrease
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

40. A restricted air filter in an air conditioning system can be identified by...
An uninsulated TXV sensing bulb
Low superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted
110-120

41. 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
Condenser fans operating during a low ambient condition and a low suction pressure
Both technicians are correct
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

42. 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
The oil pump pressure and the crankcase pressure
110-120
An undercharge and low ambient conditions

43. Which of the following will cause excessive discharge pressures on an air conditioning system...
It would cause the low-side pressure to decrease
The low-side pressure will decrease and the evaporator coil will be partially frosted
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician A is correct

44. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician A
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The superheat increases and the subcooling decreases
Both technicians are correct

45. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
A vacuum test+oil traces around fittings+soap bubble solution
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An overcharged system

46. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Whenever necessary
An increase in suction pressure and an increase in discharge pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
110-120

47. 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...
The external equalizer could be plugged
A sensing bulb improperly connected to the suction line
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
High superheat and low discharge pressure

48. 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
Technician B
An undercharge and low ambient conditions
Bad compressor valve
Clean the condenser coil

49. Air filters should be replaced...
Broken rings+broken valves+seized bearings
'G' to 'C'
Whenever necessary
A blown fuse

50. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An overcharged system
A dirty condenser - recirculation of condenser air - and a defective condenser fan