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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 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
Both technicians are incorrect
Both technicians are correct
A defective circuit breaker
A start relay

2. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Condenser fans operating during a low ambient condition and a low suction pressure
Short cycling and insufficient dehumidification
Technician B
The discharge pressure increases and the amperage increases

3. Which of the following will cause excessive discharge pressures on an air conditioning system...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The external equalizer could be plugged
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

4. Which of the following will cause excessive discharge pressures on an air conditioning system...
20 to 30
The discharge pressure increases and the amperage increases
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

5. Superheat is found in an air conditioning system in the...
A plugged filter drier
Evaporator and compressor
Partially frosted evaporator and high superheat
Technician B

6. What is the purpose of a CPR valve...
An overcharged system
A restricted metering device
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

7. 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
Condenser fans operating during a low ambient condition and a low suction pressure
110-120
High superheat and low discharge pressure

8. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A defective circuit breaker
Run with high head and high suction pressure
High suction pressure and low superheat

9. What are the symptoms of an air conditioning system that has a low charge...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A start relay
An increase of air leakage from ductwork
It would cause the low-side pressure to decrease

10. 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
Bad compressor valve
An increase of air leakage from ductwork
An increase in low-side pressure

11. Which of the following can cause excessive subcooling...
Low discharge pressure - high suction pressure - and low amp draw
An overcharged system
The discharge pressure increases and the amperage increases
Lack of airflow

12. What are three methods for controlling a system's high-side pressure during low ambient conditions...
High suction pressure and low superheat
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B
A vacuum test+oil traces around fittings+soap bubble solution

13. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
A missing air filter+improper rotation of the indoor blower+blower too small
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A sensing bulb improperly connected to the suction line

14. 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...
Technician B
It keeps a constant superheat in the evaporator
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

15. 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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16. 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
The low-side pressure will decrease and the evaporator coil will be partially frosted
The superheat will increase and the low-side pressure will decrease
An increase of air leakage from ductwork

17. What causes the automatic expansion valve to close...
An increase in low-side pressure
High suction pressure and low superheat
Run with high head and high suction pressure
Evaporator and compressor

18. 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
20 to 30
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Both technicians are correct
The external equalizer could be plugged

19. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
110-120
Run with high head and high suction pressure
Clean the condenser coil
The superheat increases and the subcooling decreases

20. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An undercharged system+insufficient airflow over the evaporator coil
Technician B
The superheat increases and the subcooling decreases
Low voltage and a faulty start relay

21. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A bad thermostat
Clean the condenser coil
Whenever necessary

22. 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
An increase in low-side pressure
Technician A
Contains a solenoid coil and one or more sets of contacts
Lack of airflow

23. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
The superheat increases and the subcooling decreases
An overcharged system
3 psig
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

24. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Low voltage and a faulty start relay
A defective circuit breaker
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

25. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Low voltage and a faulty start relay
Rise more than normal
An acid-core suction line drier
Technician B

26. 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
A missing air filter+improper rotation of the indoor blower+blower too small
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
A plugged filter drier

27. Why is it unsafe to operate an air conditioning system with a low charge...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The discharge pressure increases and the amperage increases
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An acid-core suction line drier

28. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
A restricted metering device
A start relay
An increase in low-side pressure

29. A system that uses a thermal electric expansion valve...
An acid-core suction line drier
Lack of airflow
An uninsulated suction line and a restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

30. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B

31. 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
The system has been overcharged+The system has air trapped in the condenser
Always have some liquid present in the bulb and diaphragm
An uninsulated TXV sensing bulb

32. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Low superheat
Partially frosted evaporator and high superheat

33. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A restricted metering device
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Bad compressor valve
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

34. 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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35. A hard-start kit consists of...
An undercharged system+insufficient airflow over the evaporator coil
Technician A is correct
It keeps a constant superheat in the evaporator
A start capacitor and a solid-state relay

36. What problem or problems can cause low discharge and suction pressure...
Evaporator and compressor
Technician B
The sensing bulb at a lower temperature than the valve body
An undercharged system+insufficient airflow over the evaporator coil

37. Superheat is found in an air conditioning system in the...
A start relay
Short cycling and insufficient dehumidification
An uninsulated suction line and a restricted metering device
Evaporator and compressor

38. What is the purpose of a CPR valve...
A low refrigerant charge
It is used to control refrigerant pressure in the compressor crankcase
20 to 30
Increases starting torque

39. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Whenever necessary
Broken rings+broken valves+seized bearings
Both technicians are incorrect

40. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Partially frosted evaporator and high superheat
Technician A
3 psig
The sight glass is full of liquid+the sight glass is full of gas

41. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The internal overload is opened
Technician B

42. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
('Y' and 'C') and ('G' and 'C')
Evaporator and compressor
The discharge pressure increases and the amperage increases

43. A 220-volt 30-amp motor circuit keeps tripping the breaker after the motor is started. The starting amperage is 60 amps. When measuring the amperage of the circuit - This is drawn for a brief moment. After startup - the amperage drops to 22 amps and
It is used to control refrigerant pressure in the compressor crankcase
The discharge pressure increases and the amperage increases
A defective circuit breaker
A missing air filter+improper rotation of the indoor blower+blower too small

44. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Whenever necessary
An undercharge and low ambient conditions
110-120
The discharge pressure increases and the amperage increases

45. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
Technician B
The sensing bulb at a lower temperature than the valve body
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

46. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The sight glass is full of liquid+the sight glass is full of gas
Bad compressor valve

47. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A bad thermostat
An undercharge and low ambient conditions
High suction pressure and low superheat

48. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
Technician B
High superheat and low discharge pressure
Bad compressor valve

49. 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 bad thermostat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B

50. 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
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
A blown fuse