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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 are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
('Y' and 'C') and ('G' and 'C')
An increase in low-side pressure
A plugged filter drier
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

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
Low discharge pressure - high suction pressure - and low amp draw
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician A
Technician B

3. What type of problems can be caused by an oversized air conditioning system...
Bad compressor valve
It would cause the low-side pressure to decrease
Broken rings+broken valves+seized bearings
Short cycling and insufficient dehumidification

4. A hard-start kit for an air conditioning system...
Increases starting torque
Technician B
A restricted metering device
It keeps a constant superheat in the evaporator

5. 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
'G' to 'C'
An uninsulated suction line and a restricted metering device
An undercharge and low ambient conditions

6. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Short cycling and insufficient dehumidification
Both technicians are correct
The discharge pressure increases and the amperage increases
A sensing bulb improperly connected to the suction line

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
Both technicians are correct
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

8. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
3 psig
An undercharge and low ambient conditions
Low voltage and a faulty start relay
Short cycling and insufficient dehumidification

9. Why is it unsafe to operate an air conditioning system with a low charge...
It keeps a constant superheat in the evaporator
Run with high head and high suction pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Always have some liquid present in the bulb and diaphragm

10. A system that uses a thermal electric expansion valve...
Both technicians are incorrect
An increase in low-side pressure
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

11. 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
Evaporator and compressor
High superheat and low discharge pressure
It is used to control refrigerant pressure in the compressor crankcase

12. 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
Broken rings+broken valves+seized bearings
Low superheat
A defective circuit breaker
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

13. 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
The superheat increases and the subcooling decreases
('Y' and 'C') and ('G' and 'C')
Technician B
A restricted metering device

14. A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that the outdoor condensing unit is operating - but the indoor blower is not in operation. Technician A says that it is possible that it is a bad fu
A restricted metering device
Bad compressor valve
The internal overload is opened
Both technicians are incorrect

15. 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
An uninsulated TXV sensing bulb
3 psig
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

16. 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
Short cycling and insufficient dehumidification
A restricted metering device
The sight glass is full of liquid+the sight glass is full of gas

17. A restricted air filter in an air conditioning system can be identified by...
Low superheat
Low voltage and a faulty start relay
The external equalizer could be plugged
Broken rings+broken valves+seized bearings

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
Technician B
The oil pump pressure and the crankcase pressure
The superheat increases and the subcooling decreases

19. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Broken rings+broken valves+seized bearings
Whenever necessary

20. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An overcharged system
Both technicians are correct
Technician B

21. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
A start capacitor and a solid-state relay
Lack of airflow
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

22. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An open internal overload protector
A start relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

23. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
Short cycling and insufficient dehumidification
It keeps a constant superheat in the evaporator
Condenser fans operating during a low ambient condition and a low suction pressure

24. 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
An increase of air leakage from ductwork
Technician B
110-120
The oil pump pressure and the crankcase pressure

25. The best description of a relay would be...
It is used to control refrigerant pressure in the compressor crankcase
A defective circuit breaker
Increases starting torque
Contains a solenoid coil and one or more sets of contacts

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
It is used to control refrigerant pressure in the compressor crankcase
110-120
A bad thermostat

27. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Current in the compressor circuit
Both technicians are incorrect
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Lack of airflow

28. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Low superheat
3 psig
An increase in low-side pressure
Clean the condenser coil

29. A restricted air filter in an air conditioning system can be identified by...
It would cause the low-side pressure to decrease
Low superheat
Run with high head and high suction pressure
Rise more than normal

30. What are two problems that can cause an air conditioning system to have an excessively high superheat...
50-65
An uninsulated suction line and a restricted metering device
An increase of air leakage from ductwork
The discharge pressure increases and the amperage increases

31. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
The external equalizer could be plugged
Technician B
An overcharged system

32. A hard-start kit consists of...
A start capacitor and a solid-state relay
An undercharged system+insufficient airflow over the evaporator coil
The sensing bulb at a lower temperature than the valve body
Condenser fans operating during a low ambient condition and a low suction pressure

33. What are common methods that are used for leak-testing a system...
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
An overcharged system
A defective circuit breaker

34. 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
The superheat increases and the subcooling decreases
3 psig
An undercharge and low ambient conditions

35. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Whenever necessary
Flooding the condenser - cycling condenser fans - and dampering condenser air
A defective circuit breaker
A dirty condenser - recirculation of condenser air - and a defective condenser fan

36. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Whenever necessary
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Low voltage and a faulty start relay
110-120

37. 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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38. Which of the following can cause excessive subcooling...
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An overcharged system
A blown fuse

39. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
A sensing bulb improperly connected to the suction line
The external equalizer could be plugged
A vacuum test+oil traces around fittings+soap bubble solution

40. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Current in the compressor circuit
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The discharge pressure increases and the amperage increases
Technician A

41. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
Clean the condenser coil
The superheat will increase and the low-side pressure will decrease
A sensing bulb improperly connected to the suction line

42. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Current in the compressor circuit
Partially frosted evaporator and high superheat
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small

43. What is the purpose of an EPR valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Condenser fans operating during a low ambient condition and a low suction pressure
Lack of airflow
The oil pump pressure and the crankcase pressure

44. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Low discharge pressure - high suction pressure - and low amp draw
Both technicians are incorrect
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Lack of airflow

45. 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
Clean the condenser coil
Technician B
Clean the condenser coil
A blown fuse

46. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Whenever necessary
An overcharged system
Rise more than normal
Lack of airflow

47. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A start capacitor and a solid-state relay
An acid-core suction line drier

48. What is the purpose of the TXV...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It keeps a constant superheat in the evaporator
110-120

49. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
('Y' and 'C') and ('G' and 'C')
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

50. 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
('Y' and 'C') and ('G' and 'C')
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
A defective circuit breaker