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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 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 vacuum test+oil traces around fittings+soap bubble solution
An uninsulated suction line and a restricted metering device
Technician B
Increases starting torque

2. What are two common symptoms of refrigerant leaks in an air conditioning system...
An undercharged system+insufficient airflow over the evaporator coil
The oil pump pressure and the crankcase pressure
A defective circuit breaker
Partially frosted evaporator and high superheat

3. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Evaporator and compressor
The superheat increases and the subcooling decreases

4. The internal overload of an air conditioning compressor senses winding temperature and...
Rise more than normal
Always have some liquid present in the bulb and diaphragm
It keeps a constant superheat in the evaporator
Current in the compressor circuit

5. 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
Both technicians are incorrect
The system has been overcharged+The system has air trapped in the condenser
A missing air filter+improper rotation of the indoor blower+blower too small
50-65

6. Why is it unsafe to operate an air conditioning system with a low charge...
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It would cause the low-side pressure to decrease
The internal overload is opened

7. A hard-start kit consists of...
Both technicians are correct
High suction pressure and low superheat
The system has been overcharged+The system has air trapped in the condenser
A start capacitor and a solid-state relay

8. 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')
An increase in low-side pressure
A defective circuit breaker
An undercharge and low ambient conditions

9. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
The superheat increases and the subcooling decreases

10. Which of the following is a common cause of an excessively low superheat on a TXV system...
20 to 30
A sensing bulb improperly connected to the suction line
The sight glass is full of liquid+the sight glass is full of gas
Bad compressor valve

11. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A low refrigerant charge
A blown fuse
Low voltage and a faulty start relay
High suction pressure and low superheat

12. 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
A sensing bulb improperly connected to the suction line
An undercharged system+insufficient airflow over the evaporator coil
An overcharged system

13. What causes the automatic expansion valve to close...
An increase in low-side pressure
110-120
A missing air filter+improper rotation of the indoor blower+blower too small
Low voltage and a faulty start relay

14. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It would cause the low-side pressure to decrease
Both technicians are correct
Partially frosted evaporator and high superheat

15. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Increases starting torque
20 to 30
Short cycling and insufficient dehumidification
An uninsulated TXV sensing bulb

16. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
Whenever necessary
A missing air filter+improper rotation of the indoor blower+blower too small
High superheat and low discharge pressure

17. A compressor having tight bearings would cause the current value to...
3 psig
The oil pump pressure and the crankcase pressure
The system has been overcharged+The system has air trapped in the condenser
Rise more than normal

18. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Contains a solenoid coil and one or more sets of contacts

19. A commercial customer calls on a 90
'G' to 'C'
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 missing air filter+improper rotation of the indoor blower+blower too small

20. What causes the automatic expansion valve to close...
Evaporator and compressor
Flooding the condenser - cycling condenser fans - and dampering condenser air
'G' to 'C'
An increase in low-side pressure

21. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It would cause the low-side pressure to decrease
An uninsulated suction line and a restricted metering device

22. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Increases starting torque
Technician B
Run with high head and high suction pressure
An overcharged system

23. A hard-start kit for an air conditioning system...
A vacuum test+oil traces around fittings+soap bubble solution
Increases starting torque
Both technicians are correct
An increase of air leakage from ductwork

24. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
An undercharged system+insufficient airflow over the evaporator coil

25. 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
Technician B
The oil pump pressure and the crankcase pressure
An undercharged system+insufficient airflow over the evaporator coil
The system has been overcharged+The system has air trapped in the condenser

26. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Increases starting torque
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The oil pump pressure and the crankcase pressure
Bad compressor valve

27. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
A start relay
Low superheat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The low-side pressure will decrease and the evaporator coil will be partially frosted

28. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Low voltage and a faulty start relay
An undercharge and low ambient conditions
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Run with high head and high suction pressure

29. A hard-start kit for an air conditioning system...
Lack of airflow
Increases starting torque
An undercharge and low ambient conditions
A start capacitor and a solid-state relay

30. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A start relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An uninsulated TXV sensing bulb
The superheat will increase and the low-side pressure will decrease

31. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
It would cause the low-side pressure to decrease
Clean the condenser coil

32. What is the purpose of a CPR valve...
Both technicians are incorrect
It is used to control refrigerant pressure in the compressor crankcase
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

33. What are common methods that are used for leak-testing a system...
An uninsulated suction line and a restricted metering device
Technician A
An uninsulated TXV sensing bulb
A vacuum test+oil traces around fittings+soap bubble solution

34. 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
Whenever necessary
An uninsulated suction line and a restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small

35. What type of problems can be caused by an oversized air conditioning system...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Short cycling and insufficient dehumidification
Low voltage and a faulty start relay
20 to 30

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
Technician A
Evaporator and compressor
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

37. What are three methods for controlling a system's high-side pressure during low ambient conditions...
The discharge pressure increases and the amperage increases
Flooding the condenser - cycling condenser fans - and dampering condenser air
A sensing bulb improperly connected to the suction line
Lack of airflow

38. What problem or problems can cause low discharge and suction pressure...
Short cycling and insufficient dehumidification
An undercharged system+insufficient airflow over the evaporator coil
Evaporator and compressor
Low superheat

39. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Technician B
Both technicians are incorrect
An acid-core suction line drier
Technician B

40. 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 blown fuse
A plugged filter drier
Broken rings+broken valves+seized bearings
A start relay

41. What problem or problems can cause low discharge and suction pressure...
The oil pump pressure and the crankcase pressure
An undercharged system+insufficient airflow over the evaporator coil
Technician B
Low voltage and a faulty start relay

42. What component is most often the cause of a start capacitor failure...
Technician B
High suction pressure and low superheat
A start relay
A defective circuit breaker

43. When using a vapor-charged TXV bulb - it is necessary to have...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the 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 dirty condenser - recirculation of condenser air - and a defective condenser fan
The sensing bulb at a lower temperature than the valve body

44. A customer calls and complains that her high-efficiency air conditioning system is operating - but is not cooling properly. Further investigation shows that the system is using a TXV type of metering device. A subcooling check shows that the system a
The external equalizer could be plugged
Contains a solenoid coil and one or more sets of contacts
Flooding the condenser - cycling condenser fans - and dampering condenser air
A defective circuit breaker

45. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
A low refrigerant charge
An overcharged system
Low discharge pressure - high suction pressure - and low amp draw

46. Which of the following could be the cause for a system's discharge and suction pressure being low...
An overcharged system
The superheat increases and the subcooling decreases
A restricted metering device
'G' to 'C'

47. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A defective circuit breaker
An uninsulated suction line and a restricted metering device
It keeps a constant superheat in the evaporator
High suction pressure and low superheat

48. 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
Evaporator and compressor
Broken rings+broken valves+seized bearings
Partially frosted evaporator and high superheat
Clean the condenser coil

49. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
It would cause the low-side pressure to decrease
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A sensing bulb improperly connected to the suction line
110-120

50. Which of the following is a common cause of an excessively low superheat on a TXV system...
It is used to control refrigerant pressure in the compressor crankcase
Technician B
A sensing bulb improperly connected to the suction line
The system has been overcharged+The system has air trapped in the condenser