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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...
A vacuum test+oil traces around fittings+soap bubble solution
20 to 30
It would cause the low-side pressure to decrease
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

2. A customer calls with an insufficient cooling complaint on a 90
The sight glass is full of liquid+the sight glass is full of gas
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
3 psig

3. 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
Run with high head and high suction pressure
The sight glass is full of liquid+the sight glass is full of gas
Whenever necessary

4. What is the purpose of the TXV...
Both technicians are correct
Lack of airflow
Always have some liquid present in the bulb and diaphragm
It keeps a constant superheat in the evaporator

5. What component is most often the cause of a start capacitor failure...
A start relay
Clean the condenser coil
The discharge pressure increases and the amperage increases
It would cause the low-side pressure to decrease

6. Which of the following could be the cause for a system's discharge and suction pressure being low...
Both technicians are incorrect
A restricted metering device
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A defective circuit breaker

7. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
A low refrigerant charge
Lack of airflow
Technician A is correct
An undercharge and low ambient conditions

8. Which of the following will cause excessive discharge pressures on an air conditioning system...
Technician A
It would cause the low-side pressure to decrease
Flooding the condenser - cycling condenser fans - and dampering condenser air
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

9. A restricted air filter in an air conditioning system can be identified by...
Run with high head and high suction pressure
The superheat will increase and the low-side pressure will decrease
The external equalizer could be plugged
Low superheat

10. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
An uninsulated TXV sensing bulb
Run with high head and high suction pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A bad thermostat

11. Which of the following could be the cause for a system's discharge and suction pressure being low...
Both technicians are correct
('Y' and 'C') and ('G' and 'C')
Technician B
A restricted metering device

12. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
It is used to control refrigerant pressure in the compressor crankcase
A missing air filter+improper rotation of the indoor blower+blower too small
Run with high head and high suction pressure
An acid-core suction line drier

13. Air filters should be replaced...
Technician B
A start capacitor and a solid-state relay
An overcharged system
Whenever necessary

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...
An increase of air leakage from ductwork
Bad compressor valve
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

15. Which of the following can cause excessive subcooling...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
50-65
An overcharged system
A missing air filter+improper rotation of the indoor blower+blower too small

16. 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
An acid-core suction line drier
An increase in low-side pressure
Condenser fans operating during a low ambient condition and a low suction pressure

17. 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
Technician B
The internal overload is opened
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A blown fuse

18. What component is most often the cause of a start capacitor failure...
Technician B
A start relay
A sensing bulb improperly connected to the suction line
Technician A

19. 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
The oil pump pressure and the crankcase pressure
A restricted metering device
A defective circuit breaker
The superheat will increase and the low-side pressure will decrease

20. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An open internal overload protector
An undercharge and low ambient conditions
A restricted metering device

21. When using a vapor-charged TXV bulb - it is necessary to have...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The external equalizer could be plugged
It keeps a constant superheat in the evaporator
The sensing bulb at a lower temperature than the valve body

22. 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 dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A plugged filter drier
The superheat will increase and the low-side pressure will decrease
Both technicians are incorrect

23. Technician A says ' When charging a system using the superheat method - adding refrigerant to the system will increase the superheat.' Technician B says 'When charging a system using the superheat method - adding refrigerant will decrease the superhe
An undercharged system+insufficient airflow over the evaporator coil
It would cause the low-side pressure to decrease
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

24. A hard-start kit consists of...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A start capacitor and a solid-state relay
The oil pump pressure and the crankcase pressure
Current in the compressor circuit

25. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
A sensing bulb improperly connected to the suction line
Technician B
Technician B
The discharge pressure increases and the amperage increases

26. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
An overcharged system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
3 psig
A start relay

27. A hard-start kit consists of...
Rise more than normal
A low refrigerant charge
A start capacitor and a solid-state relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

28. What problem or problems can cause low discharge and suction pressure...
An uninsulated TXV sensing bulb
An undercharged system+insufficient airflow over the evaporator coil
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An overcharged system

29. A hard-start kit for an air conditioning system...
It would cause the low-side pressure to decrease
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Increases starting torque
A blown fuse

30. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Bad compressor valve
An uninsulated TXV sensing bulb
Technician B
An overcharged system

31. 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
A restricted metering device
Both technicians are correct
Broken rings+broken valves+seized bearings

32. 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
Rise more than normal
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser

33. What is the purpose of a CPR valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Current in the compressor circuit
It is used to control refrigerant pressure in the compressor crankcase

34. A restricted air filter in an air conditioning system can be identified by...
Low superheat
Run with high head and high suction pressure
It is used to control refrigerant pressure in the compressor crankcase
Technician B

35. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician B
Technician B
Bad compressor valve
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

36. 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
Rise more than normal
A low refrigerant charge
Technician A
The external equalizer could be plugged

37. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
Bad compressor valve
'G' to 'C'
The system has been overcharged+The system has air trapped in the condenser

38. Which of the following is a possible cause for a compressor to overheat...
Technician B
'G' to 'C'
Technician B
A low refrigerant charge

39. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
50-65
A missing air filter+improper rotation of the indoor blower+blower too small
Current in the compressor circuit

40. A system that uses a thermal electric expansion valve...
A restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Lack of airflow

41. What are two common symptoms of refrigerant leaks in an air conditioning system...
An open internal overload protector
Partially frosted evaporator and high superheat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B

42. Superheat is found in an air conditioning system in the...
Evaporator and compressor
Technician A is correct
A missing air filter+improper rotation of the indoor blower+blower too small
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

43. A customer calls with an insufficient cooling complaint on a 90
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
It keeps a constant superheat in the evaporator
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

44. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Condenser fans operating during a low ambient condition and a low suction pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Broken rings+broken valves+seized bearings

45. What are the symptoms of a TXV air conditioning system if it has lost its charge...
20 to 30
The superheat will increase and the low-side pressure will decrease
The sight glass is full of liquid+the sight glass is full of gas
Broken rings+broken valves+seized bearings

46. 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 oil pump pressure and the crankcase pressure
Technician A is correct
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

47. The temperature range of the suction line from an air conditioning system should be...
An acid-core suction line drier
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Condenser fans operating during a low ambient condition and a low suction pressure
50-65

48. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated suction line and a restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure
An undercharge and low ambient conditions
A low refrigerant charge

49. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A blown fuse
Technician B
Low superheat
An increase in suction pressure and an increase in discharge pressure

50. What is the purpose of an EPR valve...
Rise more than normal
A blown fuse
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Increases starting torque