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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 is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
An increase in suction pressure and an increase in discharge pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
20 to 30

2. A customer calls with an insufficient cooling complaint on a 90
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Low superheat
Always have some liquid present in the bulb and diaphragm

3. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
110-120
It would cause the low-side pressure to decrease
An overcharged system

4. The internal overload of an air conditioning compressor senses winding temperature and...
An increase of air leakage from ductwork
Both technicians are correct
High superheat and low discharge pressure
Current in the compressor circuit

5. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
It is used to control refrigerant pressure in the compressor crankcase
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An open internal overload protector
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

6. 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
20 to 30
Contains a solenoid coil and one or more sets of contacts
Run with high head and high suction pressure

7. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The sensing bulb at a lower temperature than the valve body
A defective circuit breaker
Low superheat

8. 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
High suction pressure and low superheat
Rise more than normal
Both technicians are incorrect
50-65

9. 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 bad thermostat
Always have some liquid present in the bulb and diaphragm
An open internal overload protector
Both technicians are incorrect

10. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The superheat increases and the subcooling decreases
Low discharge pressure - high suction pressure - and low amp draw
High suction pressure and low superheat
An overcharged system

11. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
An increase in suction pressure and an increase in discharge pressure
High suction pressure and low superheat
Evaporator and compressor

12. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The oil pump pressure and the crankcase pressure
110-120
Low discharge pressure - high suction pressure - and low amp draw
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

13. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Contains a solenoid coil and one or more sets of contacts
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The low-side pressure will decrease and the evaporator coil will be partially frosted

14. 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
An undercharged system+insufficient airflow over the evaporator coil
An acid-core suction line drier
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A defective circuit breaker

15. What are the symptoms of an air conditioning system that has a low charge...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
'G' to 'C'

16. 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 system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An overcharged system
Increases starting torque
The external equalizer could be plugged

17. The temperature range of the suction line from an air conditioning system should be...
An increase of air leakage from ductwork
50-65
The superheat increases and the subcooling decreases
'G' to 'C'

18. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are correct

19. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An overcharged system
An open internal overload protector

20. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
Evaporator and compressor
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Dirty condenser - bent condenser fins - and air recirculating over the condenser

21. What is the common cause of a compressor burnout...
The sensing bulb at a lower temperature than the valve body
Low voltage and a faulty start relay
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A plugged filter drier

22. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
An undercharged system+insufficient airflow over the evaporator coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Broken rings+broken valves+seized bearings

23. What is the purpose of a CPR valve...
'G' to 'C'
It is used to control refrigerant pressure in the compressor crankcase
A start relay
High suction pressure and low superheat

24. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Evaporator and compressor
A plugged filter drier
Technician A
Low voltage and a faulty start relay

25. What is the common cause of a compressor burnout...
An undercharge and low ambient conditions
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
A bad thermostat

26. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Clean the condenser coil
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The sensing bulb at a lower temperature than the valve body
High suction pressure and low superheat

27. 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
Technician B
Technician A
An increase of air leakage from ductwork
The sight glass is full of liquid+the sight glass is full of gas

28. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
An overcharged system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A blown fuse

29. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
It keeps a constant superheat in the evaporator
Technician B
3 psig
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

30. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Run with high head and high suction pressure
The discharge pressure increases and the amperage increases
Technician B

31. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The superheat will increase and the low-side pressure will decrease
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The sensing bulb at a lower temperature than the valve body
A dirty condenser - recirculation of condenser air - and a defective condenser fan

32. 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
Partially frosted evaporator and high superheat
Technician B
Run with high head and high suction pressure
An uninsulated TXV sensing bulb

33. A system that uses a thermal electric expansion valve...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Current in the compressor circuit
Lack of airflow
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

34. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Technician B
Technician B
An undercharged system+insufficient airflow over the evaporator coil
Run with high head and high suction pressure

35. 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...
An increase in low-side pressure
An overcharged system
Whenever necessary
Low voltage and a faulty start relay

36. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
3 psig
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It keeps a constant superheat in the evaporator
An increase of air leakage from ductwork

37. 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
A low refrigerant charge
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An overcharged system
Technician B

38. The temperature range of the suction line from an air conditioning system should be...
20 to 30
Whenever necessary
50-65
Technician A is correct

39. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Technician B
It would cause the low-side pressure to decrease
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Increases starting torque

40. The best description of a relay would be...
Technician B
It would cause the low-side pressure to decrease
Contains a solenoid coil and one or more sets of contacts
A low refrigerant charge

41. 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
A bad thermostat
A sensing bulb improperly connected to the suction line
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It is used to control refrigerant pressure in the compressor crankcase

42. 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
A plugged filter drier
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Both technicians are correct
Technician B

43. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An increase in low-side pressure
An uninsulated suction line and a restricted metering device
An overcharged system
Technician A is correct

44. What problem or problems can cause low discharge and suction pressure...
High superheat and low discharge pressure
A sensing bulb improperly connected to the suction line
Technician B
An undercharged system+insufficient airflow over the evaporator coil

45. Air filters should be replaced...
Contains a solenoid coil and one or more sets of contacts
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A missing air filter+improper rotation of the indoor blower+blower too small
Whenever necessary

46. What is the purpose of an EPR valve...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The sensing bulb at a lower temperature than the valve body
Low superheat

47. Which of the following is a common cause of an excessively low superheat on a TXV system...
An increase of air leakage from ductwork
An increase in low-side pressure
A sensing bulb improperly connected to the suction line
Both technicians are incorrect

48. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
Evaporator and compressor
Always have some liquid present in the bulb and diaphragm
It would cause the low-side pressure to decrease

49. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Contains a solenoid coil and one or more sets of contacts

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
A start relay
An open internal overload protector
A sensing bulb improperly connected to the suction line
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay