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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 are the symptoms of an air conditioning system that has a low charge...
Technician B
Broken rings+broken valves+seized bearings
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted

2. A restricted air filter in an air conditioning system can be identified by...
The system has been overcharged+The system has air trapped in the condenser
Technician B
Low superheat
It keeps a constant superheat in the evaporator

3. Air filters should be replaced...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An overcharged system
Partially frosted evaporator and high superheat
Whenever necessary

4. 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
The sight glass is full of liquid+the sight glass is full of gas
The internal overload is opened
An undercharge and low ambient conditions
Technician B

5. Insufficient airflow can be caused by...
The discharge pressure increases and the amperage increases
Both technicians are correct
An increase of air leakage from ductwork
Low superheat

6. 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
Broken rings+broken valves+seized bearings
Lack of airflow
Dirty condenser - bent condenser fins - and air recirculating over the condenser

7. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An increase of air leakage from ductwork
An overcharged system
The superheat will increase and the low-side pressure will decrease
The external equalizer could be plugged

8. 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
Low discharge pressure - high suction pressure - and low amp draw
A low refrigerant charge
Technician B
An increase in low-side pressure

9. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An undercharge and low ambient conditions
An open internal overload protector

10. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A start relay
An overcharged system
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
High suction pressure and low superheat

11. 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...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A blown fuse
Run with high head and high suction pressure
Lack of airflow

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

13. A compressor having tight bearings would cause the current value to...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The superheat increases and the subcooling decreases
Rise more than normal
50-65

14. When using a vapor-charged TXV bulb - it is necessary to have...
Partially frosted evaporator and high superheat
The sensing bulb at a lower temperature than the valve body
The discharge pressure increases and the amperage increases
An uninsulated suction line and a restricted metering device

15. Which of the following can cause excessive subcooling...
An overcharged system
The low-side pressure will decrease and the evaporator coil will be partially frosted
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Current in the compressor circuit

16. What three things can prevent an air conditioning system from releasing heat at the proper rate...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
Bad compressor valve

17. 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
A defective circuit breaker
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
Both technicians are incorrect

18. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
Technician A
The external equalizer could be plugged
An overcharged system

19. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Current in the compressor circuit
110-120
Whenever necessary
Low discharge pressure - high suction pressure - and low amp draw

20. 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 voltage and a faulty start relay
High superheat and low discharge pressure
It would cause the low-side pressure to decrease
Both technicians are incorrect

21. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
20 to 30
It is used to control refrigerant pressure in the compressor crankcase
Rise more than normal
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

22. What is the common cause of a compressor burnout...
A restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Flooding the condenser - cycling condenser fans - and dampering condenser air
An uninsulated TXV sensing bulb

23. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A vacuum test+oil traces around fittings+soap bubble solution
A defective circuit breaker
Clean the condenser coil

24. Which of the following will cause excessive discharge pressures on an air conditioning 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
Low voltage and a faulty start relay
An acid-core suction line drier

25. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Low voltage and a faulty start relay
The superheat will increase and the low-side pressure will decrease
High superheat and low discharge pressure
Technician B

26. 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
Both technicians are incorrect
An uninsulated suction line and a restricted metering device
An overcharged system

27. 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
('Y' and 'C') and ('G' and 'C')
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

28. 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
An overcharged system
Technician A
Technician A is correct
A sensing bulb improperly connected to the suction line

29. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
High superheat and low discharge pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An overcharged system
Technician A

30. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An overcharged system
An increase in suction pressure and an increase in discharge pressure
'G' to 'C'
A low refrigerant charge

31. 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 refrigerant charge
Whenever necessary
The sight glass is full of liquid+the sight glass is full of gas
An open internal overload protector

32. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
A sensing bulb improperly connected to the suction line
A start capacitor and a solid-state relay

33. What are two common symptoms of refrigerant leaks in an air conditioning system...
3 psig
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A blown fuse
Partially frosted evaporator and high superheat

34. 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 internal overload is opened
A defective circuit breaker
The external equalizer could be plugged
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

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 sight glass is full of liquid+the sight glass is full of gas
The superheat increases and the subcooling decreases
An undercharge and low ambient conditions
Technician A is correct

36. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Both technicians are incorrect
3 psig
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The low-side pressure will decrease and the evaporator coil will be partially frosted

37. 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
It would cause the low-side pressure to decrease
Partially frosted evaporator and high superheat
It keeps a constant superheat in the evaporator

38. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Run with high head and high suction pressure
Contains a solenoid coil and one or more sets of contacts
An open internal overload protector
50-65

39. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The superheat will increase and the low-side pressure will decrease
Always have some liquid present in the bulb and diaphragm
High suction pressure and low superheat
A dirty condenser - recirculation of condenser air - and a defective condenser fan

40. What is the purpose of the TXV...
A vacuum test+oil traces around fittings+soap bubble solution
The oil pump pressure and the crankcase pressure
It keeps a constant superheat in the evaporator
The internal overload is opened

41. 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
Broken rings+broken valves+seized bearings
Rise more than normal
It is used to control refrigerant pressure in the compressor crankcase
An acid-core suction line drier

42. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Technician B
Technician A
An undercharge and low ambient conditions
The sensing bulb at a lower temperature than the valve body

43. 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
An acid-core suction line drier
A defective circuit breaker
'G' to 'C'
A bad thermostat

44. The internal overload of an air conditioning compressor senses winding temperature and...
An undercharged system+insufficient airflow over the evaporator coil
A bad thermostat
Current in the compressor circuit
Always have some liquid present in the bulb and diaphragm

45. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
Technician B
3 psig
Dirty condenser - bent condenser fins - and air recirculating over the condenser

46. A system that is operating with a clear sight glass shows...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Bad compressor valve
The sight glass is full of liquid+the sight glass is full of gas
The system has been overcharged+The system has air trapped in the condenser

47. 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
Bad compressor valve
Technician B
The superheat will increase and the low-side pressure will decrease

48. What is the purpose of a CPR valve...
An uninsulated TXV sensing bulb
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The superheat increases and the subcooling decreases
It is used to control refrigerant pressure in the compressor crankcase

49. 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...
The system has been overcharged+The system has air trapped in the condenser
Condenser fans operating during a low ambient condition and a low suction pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A missing air filter+improper rotation of the indoor blower+blower too small

50. What are common methods that are used for leak-testing a system...
An increase in low-side pressure
A vacuum test+oil traces around fittings+soap bubble solution
The external equalizer could be plugged
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged