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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 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 A
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A low refrigerant charge
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

2. 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
It keeps a constant superheat in the evaporator
A plugged filter drier
Evaporator and compressor
Both technicians are incorrect

3. Why is it unsafe to operate an air conditioning system with a low charge...
Low discharge pressure - high suction pressure - and low amp draw
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
20 to 30
High superheat and low discharge pressure

4. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Current in the compressor circuit
An increase of air leakage from ductwork
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Both technicians are correct

5. 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
Current in the compressor circuit
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
('Y' and 'C') and ('G' and 'C')

6. A system that is being serviced has been evacuated down to 500 microns. When the gauges are closed and the vacuum pump is turned off - the pressure starts to increase and stops at 1000 microns. Technician A says that the system has a leak and needs t
Rise more than normal
Technician B
Low voltage and a faulty start relay
110-120

7. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An undercharged system+insufficient airflow over the evaporator coil
The sensing bulb at a lower temperature than the valve body

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
Whenever necessary
A defective circuit breaker
Flooding the condenser - cycling condenser fans - and dampering condenser air
A plugged filter drier

9. What type of problems can be caused by an oversized air conditioning system...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Flooding the condenser - cycling condenser fans - and dampering condenser air
Short cycling and insufficient dehumidification
Bad compressor valve

10. A liquid-charged TXV bulb will...
Technician B
Evaporator and compressor
An increase of air leakage from ductwork
Always have some liquid present in the bulb and diaphragm

11. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A plugged filter drier
A dirty condenser - recirculation of condenser air - and a defective condenser fan
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

12. Why is it unsafe to operate an air conditioning system with a low charge...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician A
The sight glass is full of liquid+the sight glass is full of gas
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

13. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
High suction pressure and low superheat
It keeps a constant superheat in the evaporator
110-120

14. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
The system has been overcharged+The system has air trapped in the condenser
An overcharged system
A plugged filter drier
High suction pressure and low superheat

15. Which of the following is a common cause of an excessively low superheat on a TXV system...
A sensing bulb improperly connected to the suction line
An open internal overload protector
Technician B
A plugged filter drier

16. What is the purpose of a CPR valve...
110-120
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It is used to control refrigerant pressure in the compressor crankcase
It would cause the low-side pressure to decrease

17. 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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18. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
The oil pump pressure and the crankcase pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser
High suction pressure and low superheat
('Y' and 'C') and ('G' and 'C')

19. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
Flooding the condenser - cycling condenser fans - and dampering condenser air
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure

20. What are the symptoms of a TXV air conditioning system if it has lost its charge...
50-65
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The superheat will increase and the low-side pressure will decrease

21. What type of problems can be caused by an oversized air conditioning system...
Technician B
A defective circuit breaker
The discharge pressure increases and the amperage increases
Short cycling and insufficient dehumidification

22. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B
The superheat increases and the subcooling decreases
A dirty condenser - recirculation of condenser air - and a defective condenser fan

23. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician A
A start capacitor and a solid-state relay

24. 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 oil pump pressure and the crankcase pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The external equalizer could be plugged

25. 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 vacuum test+oil traces around fittings+soap bubble solution
A missing air filter+improper rotation of the indoor blower+blower too small
Broken rings+broken valves+seized bearings
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 restricted metering device
Both technicians are incorrect
'G' to 'C'
A missing air filter+improper rotation of the indoor blower+blower too small

27. Which of the following is a common cause of an excessively low superheat on a TXV system...
An overcharged system
Evaporator and compressor
A sensing bulb improperly connected to the suction line
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

28. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Bad compressor valve

29. If 24 volts are present to the contactor coil on an air conditioning system and the condenser fan or compressor is inoperative - which of the following could be at fault...
A blown fuse
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Run with high head and high suction pressure

30. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
The system has been overcharged+The system has air trapped in the condenser
The external equalizer could be plugged
Technician B

31. 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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32. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
High suction pressure and low superheat
An overcharged system

33. 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
The discharge pressure increases and the amperage increases
3 psig
Technician B

34. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
110-120
Run with high head and high suction pressure
The sight glass is full of liquid+the sight glass is full of gas
An acid-core suction line drier

35. What causes the automatic expansion valve to close...
Technician B
An increase in low-side pressure
Evaporator and compressor
An overcharged system

36. What are two common symptoms of refrigerant leaks in an air conditioning system...
The internal overload is opened
An increase in low-side pressure
Partially frosted evaporator and high superheat
It keeps a constant superheat in the evaporator

37. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An increase in suction pressure and an increase in discharge pressure
An acid-core suction line drier
The oil pump pressure and the crankcase pressure

38. A hard-start kit for an air conditioning system...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Increases starting torque
A defective circuit breaker
An increase in low-side pressure

39. If a rooftop air conditioning system does not have any means of low ambient protection - what will be two symptoms of the system when operating under a low ambient condition...
Low superheat
Both technicians are correct
A low refrigerant charge
High superheat and low discharge pressure

40. 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
An undercharge and low ambient conditions
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
Both technicians are incorrect

41. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The system has been overcharged+The system has air trapped in the condenser
Both technicians are correct
20 to 30
The external equalizer could be plugged

42. A hard-start kit for an air conditioning system...
An open internal overload protector
Run with high head and high suction pressure
Increases starting torque
('Y' and 'C') and ('G' and 'C')

43. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A blown fuse
An uninsulated suction line and a restricted metering device
20 to 30

44. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
High suction pressure and low superheat

45. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
An increase in suction pressure and an increase in discharge pressure
Technician A
Both technicians are correct
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

46. 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
An overcharged system
Condenser fans operating during a low ambient condition and a low suction pressure
The oil pump pressure and the crankcase pressure
Technician A is correct

47. 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
'G' to 'C'
A blown fuse
A sensing bulb improperly connected to the suction line

48. Which of the following can cause low superheat in a TXV system...
The external equalizer could be plugged
Clean the condenser coil
Increases starting torque
An uninsulated TXV sensing bulb

49. Air filters should be replaced...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
('Y' and 'C') and ('G' and 'C')
Whenever necessary
Bad compressor valve

50. What are the symptoms of an air conditioning system that has a low charge...
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
A low refrigerant charge
The system has been overcharged+The system has air trapped in the condenser