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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
Whenever necessary
It would cause the low-side pressure to decrease
Technician A
Rise more than normal

2. 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...

3. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
3 psig
Broken rings+broken valves+seized bearings
The oil pump pressure and the crankcase pressure

4. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
3 psig
It would cause the low-side pressure to decrease
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The sight glass is full of liquid+the sight glass is full of gas

5. 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
Both technicians are incorrect
It is used to control refrigerant pressure in the compressor crankcase
Technician B
A vacuum test+oil traces around fittings+soap bubble solution

6. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
Rise more than normal
20 to 30
The discharge pressure increases and the amperage increases

7. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
('Y' and 'C') and ('G' and 'C')
Technician B
Clean the condenser coil
The oil pump pressure and the crankcase pressure

8. Which of the following is a possible cause for a compressor to overheat...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A low refrigerant charge
('Y' and 'C') and ('G' and 'C')
It would cause the low-side pressure to decrease

9. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
The external equalizer could be plugged
An uninsulated suction line and a restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

10. What component is most often the cause of a start capacitor failure...
A start relay
('Y' and 'C') and ('G' and 'C')
Evaporator and compressor
A low refrigerant charge

11. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
3 psig
An uninsulated TXV sensing bulb
Clean the condenser coil
An undercharge and low ambient conditions

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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B
Broken rings+broken valves+seized bearings
The sight glass is full of liquid+the sight glass is full of gas

13. 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 start relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B
Both technicians are incorrect

14. The best description of a relay would be...
Both technicians are incorrect
An open internal overload protector
Contains a solenoid coil and one or more sets of contacts
The sensing bulb at a lower temperature than the valve body

15. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
('Y' and 'C') and ('G' and 'C')
High suction pressure and low superheat
The oil pump pressure and the crankcase pressure

16. The temperature range of the suction line from an air conditioning system should be...
Partially frosted evaporator and high superheat
Run with high head and high suction pressure
The superheat increases and the subcooling decreases
50-65

17. Which of the following can cause low superheat in a TXV system...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
The system has been overcharged+The system has air trapped in the condenser
An uninsulated TXV sensing bulb

18. What are the symptoms of an air conditioning system that has a low charge...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A start capacitor and a solid-state relay
An undercharged system+insufficient airflow over the evaporator coil
The low-side pressure will decrease and the evaporator coil will be partially frosted

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 system has been overcharged+The system has air trapped in the condenser
A defective circuit breaker
It keeps a constant superheat in the evaporator
High suction pressure and low superheat

20. 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
110-120
An undercharge and low ambient conditions
An overcharged system

21. 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
An increase in suction pressure and an increase in discharge pressure
An uninsulated suction line and a restricted metering device
Bad compressor valve

22. What is the common cause of a compressor burnout...
Broken rings+broken valves+seized bearings
An uninsulated suction line and a restricted metering device
Run with high head and high suction pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

23. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
The system has been overcharged+The system has air trapped in the condenser
The sight glass is full of liquid+the sight glass is full of gas
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Run with high head and high suction pressure

24. When using a vapor-charged TXV bulb - it is necessary to have...
The sensing bulb at a lower temperature than the valve body
Clean the condenser coil
It keeps a constant superheat in the evaporator
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

25. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
110-120
Technician B
It keeps a constant superheat in the evaporator

26. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
110-120
('Y' and 'C') and ('G' and 'C')

27. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
Both technicians are correct
The oil pump pressure and the crankcase pressure
Partially frosted evaporator and high superheat

28. What is the purpose of a CPR valve...
Increases starting torque
It is used to control refrigerant pressure in the compressor crankcase
20 to 30
Partially frosted evaporator and high superheat

29. The best description of a relay would be...
An overcharged system
Technician A
An open internal overload protector
Contains a solenoid coil and one or more sets of contacts

30. 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...
Low voltage and a faulty start relay
Flooding the condenser - cycling condenser fans - and dampering condenser air
('Y' and 'C') and ('G' and 'C')
A plugged filter drier

31. Why is it unsafe to operate an air conditioning system with a low charge...
The system has been overcharged+The system has air trapped in the condenser
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
High suction pressure and low superheat

32. A restricted air filter in an air conditioning system can be identified by...
Low superheat
Whenever necessary
Flooding the condenser - cycling condenser fans - and dampering condenser air
Broken rings+broken valves+seized bearings

33. 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
Technician B
It keeps a constant superheat in the evaporator
An increase of air leakage from ductwork

34. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A bad thermostat
An overcharged system
The sight glass is full of liquid+the sight glass is full of gas

35. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A defective circuit breaker
Technician A is correct
Condenser fans operating during a low ambient condition and a low suction pressure

36. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Lack of airflow
Whenever necessary
Technician B

37. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Technician B
The superheat increases and the subcooling decreases
The oil pump pressure and the crankcase pressure
An overcharged system

38. 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 B
Current in the compressor circuit
An overcharged system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

39. 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...

40. 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
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
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

41. A commercial customer calls on a 90
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system has been overcharged+The system has air trapped in the condenser
'G' to 'C'

42. 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

43. A restricted air filter in an air conditioning system can be identified by...
Low superheat
An undercharged system+insufficient airflow over the evaporator coil
High suction pressure and low superheat
A sensing bulb improperly connected to the suction line

44. 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 dirty evaporator coil+a plugged air filter+a bad indoor blower relay
110-120
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

45. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
Technician B
Increases starting torque
Technician B

46. A hard-start kit consists of...
An acid-core suction line drier
An increase in low-side pressure
A start capacitor and a solid-state relay
110-120

47. 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 oil pump pressure and the crankcase pressure
The superheat increases and the subcooling decreases
A plugged filter drier

48. 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 start relay
Technician B
An overcharged system
A plugged filter drier

49. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
It would cause the low-side pressure to decrease
A plugged filter drier
A bad thermostat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

50. A customer calls with an insufficient cooling complaint on a 90
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
Technician B
Contains a solenoid coil and one or more sets of contacts