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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. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Low voltage and a faulty start relay
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Rise more than normal
An overcharged system

2. What are the symptoms of an air conditioning system that has a low charge...
Run with high head and high suction pressure
The sight glass is full of liquid+the sight glass is full of gas
The low-side pressure will decrease and the evaporator coil will be partially frosted
50-65

3. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Low discharge pressure - high suction pressure - and low amp draw
An increase in low-side pressure

4. What component is most often the cause of a start capacitor failure...
The system has been overcharged+The system has air trapped in the condenser
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A low refrigerant charge
A start relay

5. 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
High superheat and low discharge pressure
Broken rings+broken valves+seized bearings
Current in the compressor circuit
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

6. Air filters should be replaced...
Technician B
Technician B
Whenever necessary
A blown fuse

7. 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
Low discharge pressure - high suction pressure - and low amp draw
A bad thermostat
An increase in suction pressure and an increase in discharge pressure
Both technicians are correct

8. What causes the automatic expansion valve to close...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An increase in low-side pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
The sensing bulb at a lower temperature than the valve body

9. 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
Broken rings+broken valves+seized bearings
Broken rings+broken valves+seized bearings
The system has been overcharged+The system has air trapped in the condenser

10. 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 oil pump pressure and the crankcase pressure
Technician B
The internal overload is opened
The sight glass is full of liquid+the sight glass is full of gas

11. What causes the automatic expansion valve to close...
Technician B
An increase in low-side pressure
An undercharged system+insufficient airflow over the evaporator coil
A dirty condenser - recirculation of condenser air - and a defective condenser fan

12. A commercial customer calls on a 90
Both technicians are correct
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The system has been overcharged+The system has air trapped in the condenser
Evaporator and compressor

13. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Low discharge pressure - high suction pressure - and low amp draw
Contains a solenoid coil and one or more sets of contacts
High suction pressure and low superheat

14. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Technician B
Always have some liquid present in the bulb and diaphragm
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Condenser fans operating during a low ambient condition and a low suction pressure

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...
50-65
An acid-core suction line drier
The system has been overcharged+The system has air trapped in the condenser
A bad thermostat

16. The temperature range of the suction line from an air conditioning system should be...
50-65
Technician A
Run with high head and high suction pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

17. A compressor motor starts and operates for a short period of time and cycles on the external overload protector. What are two possible problems that could cause this...
Low voltage and a faulty start relay
The external equalizer could be plugged
Increases starting torque
An open internal overload protector

18. A hard-start kit for an air conditioning system...
The external equalizer could be plugged
Technician B
Increases starting torque
A dirty condenser - recirculation of condenser air - and a defective condenser fan

19. 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...
An undercharge and low ambient conditions
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician A
A blown fuse

20. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Technician B
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
Low discharge pressure - high suction pressure - and low amp draw

21. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
A start relay
Both technicians are correct
Lack of airflow

22. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It would cause the low-side pressure to decrease
Low superheat
'G' to 'C'
Broken rings+broken valves+seized bearings

23. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The low-side pressure will decrease and the evaporator coil will be partially frosted
The sight glass is full of liquid+the sight glass is full of gas
Contains a solenoid coil and one or more sets of contacts
A dirty condenser - recirculation of condenser air - and a defective condenser fan

24. Which of the following can cause excessive subcooling...
An overcharged system
The external equalizer could be plugged
An undercharge and low ambient conditions
The superheat will increase and the low-side pressure will decrease

25. Which of the following can cause excessive subcooling...
A restricted metering device
Both technicians are incorrect
Technician B
An overcharged system

26. 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
The system has been overcharged+The system has air trapped in the condenser
It is used to control refrigerant pressure in the compressor crankcase
Both technicians are incorrect
Technician B

27. 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
Current in the compressor circuit
Technician A is correct
Contains a solenoid coil and one or more sets of contacts

28. A customer calls with an insufficient cooling complaint on a 90
Bad compressor valve
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Low voltage and a faulty start relay

29. The temperature range of the suction line from an air conditioning system should be...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The internal overload is opened
The oil pump pressure and the crankcase pressure
50-65

30. 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 incorrect
Contains a solenoid coil and one or more sets of contacts
Both technicians are correct

31. A compressor motor starts and operates for a short period of time and cycles on the external overload protector. What are two possible problems that could cause this...
Low voltage and a faulty start relay
A blown fuse
20 to 30
Low superheat

32. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
110-120
Condenser fans operating during a low ambient condition and a low suction pressure
The external equalizer could be plugged
A missing air filter+improper rotation of the indoor blower+blower too small

33. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
20 to 30
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
50-65

34. What type of problems can be caused by an oversized air conditioning system...
Low discharge pressure - high suction pressure - and low amp draw
Short cycling and insufficient dehumidification
110-120
20 to 30

35. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
A restricted metering device
50-65
An overcharged system

36. A technician receives an air conditioning service call stating that the system is operating but isn't cooling properly. When the technician arrives - she notices that the compressor has recently been changed and it is an are-22 system. She checks the
The sight glass is full of liquid+the sight glass is full of gas
20 to 30
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Contains a solenoid coil and one or more sets of contacts

37. What problem or problems can cause low discharge and suction pressure...
A plugged filter drier
Contains a solenoid coil and one or more sets of contacts
Technician B
An undercharged system+insufficient airflow over the evaporator coil

38. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A restricted metering device
Technician B
Always have some liquid present in the bulb and diaphragm
110-120

39. 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
110-120
A vacuum test+oil traces around fittings+soap bubble solution
A bad thermostat
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

40. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A start relay
Lack of airflow
An increase in low-side pressure

41. 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
It would cause the low-side pressure to decrease
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Broken rings+broken valves+seized bearings

42. 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
A missing air filter+improper rotation of the indoor blower+blower too small
High superheat and low discharge pressure
Technician B
Low discharge pressure - high suction pressure - and low amp draw

43. 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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44. 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
Bad compressor valve
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Flooding the condenser - cycling condenser fans - and dampering condenser air

45. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An undercharged system+insufficient airflow over the evaporator coil
An uninsulated suction line and a restricted metering device
An open internal overload protector
High superheat and low discharge pressure

46. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Increases starting torque
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
A dirty condenser - recirculation of condenser air - and a defective condenser fan

47. 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
'G' to 'C'
A start relay
Clean the condenser coil
20 to 30

48. Which of the following will cause excessive discharge pressures on an air conditioning system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Run with high head and high suction pressure
Whenever necessary
Technician B

49. 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
The oil pump pressure and the crankcase pressure
50-65
Contains a solenoid coil and one or more sets of contacts

50. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
A missing air filter+improper rotation of the indoor blower+blower too small
An acid-core suction line drier
The internal overload is opened
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged