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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 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 sensing bulb improperly connected to the suction line
Rise more than normal
Broken rings+broken valves+seized bearings
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

2. What type of problems can be caused by an oversized air conditioning system...
Low voltage and a faulty start relay
A defective circuit breaker
A restricted metering device
Short cycling and insufficient dehumidification

3. 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
A plugged filter drier
20 to 30
Technician B

4. Insufficient airflow can be caused by...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An increase of air leakage from ductwork
20 to 30
An increase in suction pressure and an increase in discharge pressure

5. 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...
A blown fuse
An overcharged system
The external equalizer could be plugged
Condenser fans operating during a low ambient condition and a low suction pressure

6. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
110-120
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician A
Low voltage and a faulty start relay

7. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
'G' to 'C'
Broken rings+broken valves+seized bearings
An increase of air leakage from ductwork
A missing air filter+improper rotation of the indoor blower+blower too small

8. 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
A plugged filter drier
Run with high head and high suction pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

9. When using a vapor-charged TXV bulb - it is necessary to have...
An overcharged system
The sensing bulb at a lower temperature than the valve body
High superheat and low discharge pressure
An acid-core suction line drier

10. 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
An acid-core suction line drier
It would cause the low-side pressure to decrease
Technician A is correct

11. 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
Technician A is correct
An increase in suction pressure and an increase in discharge pressure
An open internal overload protector
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

12. 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
20 to 30
A bad thermostat
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Broken rings+broken valves+seized bearings

13. Which of the following will cause excessive discharge pressures on an air conditioning system...
Technician B
An open internal overload protector
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The sight glass is full of liquid+the sight glass is full of gas

14. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
An undercharge and low ambient conditions
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Low superheat

15. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
'G' to 'C'
The superheat will increase and the low-side pressure will decrease
Flooding the condenser - cycling condenser fans - and dampering condenser air

16. A system that is operating with a clear sight glass shows...
An uninsulated suction line and a restricted metering device
The sight glass is full of liquid+the sight glass is full of gas
The oil pump pressure and the crankcase pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

17. Superheat is found in an air conditioning system in the...
The superheat increases and the subcooling decreases
'G' to 'C'
Technician A
Evaporator and compressor

18. 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...
A plugged filter drier
A start relay
Rise more than normal
Condenser fans operating during a low ambient condition and a low suction pressure

19. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Current in the compressor circuit
20 to 30
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

20. What problem or problems can cause low discharge and suction pressure...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
High suction pressure and low superheat
Lack of airflow
An undercharged system+insufficient airflow over the evaporator coil

21. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Lack of airflow
3 psig
20 to 30
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

22. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Both technicians are incorrect
Partially frosted evaporator and high superheat
The sight glass is full of liquid+the sight glass is full of gas
Run with high head and high suction pressure

23. 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
Technician B
Both technicians are correct
Flooding the condenser - cycling condenser fans - and dampering condenser air
A plugged filter drier

24. A hard-start kit consists of...
The internal overload is opened
A restricted metering device
A start capacitor and a solid-state relay
Run with high head and high suction pressure

25. 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
Technician A
The internal overload is opened
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

26. 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
A bad thermostat
An undercharge and low ambient conditions
The sensing bulb at a lower temperature than the valve body

27. 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
Technician B
The oil pump pressure and the crankcase pressure
A defective circuit breaker
A sensing bulb improperly connected to the suction line

28. What component is most often the cause of a start capacitor failure...
Technician B
A low refrigerant charge
Increases starting torque
A start relay

29. What are common methods that are used for leak-testing a system...
Run with high head and high suction pressure
A vacuum test+oil traces around fittings+soap bubble solution
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An open internal overload protector

30. A hard-start kit for an air conditioning system...
Run with high head and high suction pressure
Increases starting torque
'G' to 'C'
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

31. Which of the following can cause low superheat in a TXV system...
A missing air filter+improper rotation of the indoor blower+blower too small
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An uninsulated TXV sensing bulb
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

32. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Condenser fans operating during a low ambient condition and a low suction pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Whenever necessary
Run with high head and high suction pressure

33. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A start relay
An overcharged system
An uninsulated TXV sensing bulb
50-65

34. Insufficient airflow can be caused by...
An increase in suction pressure and an increase in discharge pressure
An increase of air leakage from ductwork
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An increase in suction pressure and an increase in discharge pressure

35. 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
Increases starting torque
Technician A
The sensing bulb at a lower temperature than the valve body
The discharge pressure increases and the amperage increases

36. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A blown fuse

37. What causes the automatic expansion valve to close...
An open internal overload protector
Technician B
An increase in low-side pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

38. 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
20 to 30
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

39. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Partially frosted evaporator and high superheat
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An increase in suction pressure and an increase in discharge pressure

40. A customer calls with an insufficient cooling complaint on a 90
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
An uninsulated suction line and a restricted metering device
A sensing bulb improperly connected to the suction line

41. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
Lack of airflow
An overcharged system
Bad compressor valve

42. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Evaporator and compressor
A dirty condenser - recirculation of condenser air - and a defective condenser fan
('Y' and 'C') and ('G' and 'C')
A low refrigerant charge

43. What is the purpose of a CPR valve...
A defective circuit breaker
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It is used to control refrigerant pressure in the compressor crankcase
50-65

44. 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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45. Which of the following can cause excessive subcooling...
A missing air filter+improper rotation of the indoor blower+blower too small
Low superheat
An overcharged system
An acid-core suction line drier

46. 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
A sensing bulb improperly connected to the suction line
The external equalizer could be plugged
High superheat and low discharge pressure

47. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Rise more than normal
Low discharge pressure - high suction pressure - and low amp draw
A missing air filter+improper rotation of the indoor blower+blower too small

48. 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
An undercharged system+insufficient airflow over the evaporator coil
The superheat will increase and the low-side pressure will decrease
It would cause the low-side pressure to decrease

49. 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
An undercharge and low ambient conditions
('Y' and 'C') and ('G' and 'C')
A plugged filter drier

50. 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
('Y' and 'C') and ('G' and 'C')
An open internal overload protector
An uninsulated suction line and a restricted metering device
Current in the compressor circuit