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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. 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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2. A system that is operating with a clear sight glass shows...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A vacuum test+oil traces around fittings+soap bubble solution
The sight glass is full of liquid+the sight glass is full of gas
Evaporator and compressor

3. 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
Technician B
The sight glass is full of liquid+the sight glass is full of gas
'G' to 'C'
Partially frosted evaporator and high superheat

4. 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 is correct
High suction pressure and low superheat
An open internal overload protector

5. 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 acid-core suction line drier
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

6. Insufficient airflow can be caused by...
A sensing bulb improperly connected to the suction line
The external equalizer could be plugged
Clean the condenser coil
An increase of air leakage from ductwork

7. Which of the following will cause excessive discharge pressures on an air conditioning system...
Current in the compressor circuit
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An acid-core suction line drier
Technician B

8. What are the operating pressures of an oil pressure safety switch...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The oil pump pressure and the crankcase pressure
Run with high head and high suction pressure

9. A hard-start kit consists of...
20 to 30
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Both technicians are correct
A start capacitor and a solid-state relay

10. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Technician B
110-120
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Lack of airflow

11. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An increase in suction pressure and an increase in discharge pressure
Technician A is correct

12. 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 missing air filter+improper rotation of the indoor blower+blower too small
Low superheat
Technician B
Increases starting torque

13. Superheat is found in an air conditioning system in the...
A sensing bulb improperly connected to the suction line
Broken rings+broken valves+seized bearings
Evaporator and compressor
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

14. What is the purpose of the TXV...
The oil pump pressure and the crankcase pressure
It keeps a constant superheat in the evaporator
Current in the compressor circuit
Low voltage and a faulty start relay

15. 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
Clean the condenser coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Bad compressor valve
Broken rings+broken valves+seized bearings

16. 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
A plugged filter drier
Technician A is correct
A bad thermostat
The sight glass is full of liquid+the sight glass is full of gas

17. A liquid-charged TXV bulb will...
Technician B
An overcharged system
Always have some liquid present in the bulb and diaphragm
'G' to 'C'

18. 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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are incorrect

19. 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
Always have some liquid present in the bulb and diaphragm
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An uninsulated TXV sensing bulb
Both technicians are incorrect

20. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
The system has been overcharged+The system has air trapped in the condenser
Technician A
Low discharge pressure - high suction pressure - and low amp draw

21. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Lack of airflow
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An uninsulated suction line and a restricted metering device
An undercharged system+insufficient airflow over the evaporator coil

22. The internal overload of an air conditioning compressor senses winding temperature and...
'G' to 'C'
Current in the compressor circuit
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A start capacitor and a solid-state relay

23. 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
Current in the compressor circuit
A blown fuse
An overcharged system

24. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An uninsulated suction line and a restricted metering device
Short cycling and insufficient dehumidification
An overcharged system

25. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Evaporator and compressor
Increases starting torque
An undercharge and low ambient conditions
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

26. 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
Technician A is correct
An undercharge and low ambient conditions
Dirty condenser - bent condenser fins - and air recirculating over the condenser

27. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
Contains a solenoid coil and one or more sets of contacts
Increases starting torque

28. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
A missing air filter+improper rotation of the indoor blower+blower too small
Short cycling and insufficient dehumidification
A vacuum test+oil traces around fittings+soap bubble solution

29. 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
Low superheat
An undercharge and low ambient conditions
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician A

30. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
An uninsulated TXV sensing bulb
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Contains a solenoid coil and one or more sets of contacts
Both technicians are incorrect

31. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
20 to 30
The discharge pressure increases and the amperage increases
An overcharged system
The superheat increases and the subcooling decreases

32. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
An increase of air leakage from ductwork
Run with high head and high suction pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Lack of airflow

33. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
110-120
Bad compressor valve
Technician B

34. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A bad thermostat
Run with high head and high suction pressure
Technician B
Both technicians are incorrect

35. 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
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A bad thermostat
A dirty condenser - recirculation of condenser air - and a defective condenser fan

36. 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...
An undercharged system+insufficient airflow over the evaporator coil
Flooding the condenser - cycling condenser fans - and dampering condenser air
The superheat increases and the subcooling decreases
A blown fuse

37. The best description of a relay would be...
Low discharge pressure - high suction pressure - and low amp draw
An uninsulated suction line and a restricted metering device
Contains a solenoid coil and one or more sets of contacts
The low-side pressure will decrease and the evaporator coil will be partially frosted

38. 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
The low-side pressure will decrease and the evaporator coil will be partially frosted
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Contains a solenoid coil and one or more sets of contacts
Both technicians are correct

39. A commercial customer calls on a 90
An undercharge and low ambient conditions
An undercharged system+insufficient airflow over the evaporator coil
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The system has been overcharged+The system has air trapped in the condenser

40. Which of the following will cause excessive discharge pressures on an air conditioning system...
The system has been overcharged+The system has air trapped in the condenser
Low discharge pressure - high suction pressure - and low amp draw
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Increases starting torque

41. Which of the following can cause excessive subcooling...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An overcharged system
A blown fuse
A blown fuse

42. What is the purpose of a CPR valve...
Increases starting torque
Bad compressor valve
Technician B
It is used to control refrigerant pressure in the compressor crankcase

43. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
A sensing bulb improperly connected to the suction line
110-120
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

44. 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
Run with high head and high suction pressure
Contains a solenoid coil and one or more sets of contacts
Low superheat
An open internal overload protector

45. When using a vapor-charged TXV bulb - it is necessary to have...
20 to 30
The sensing bulb at a lower temperature than the valve body
The superheat increases and the subcooling decreases
Low discharge pressure - high suction pressure - and low amp draw

46. Why is it unsafe to operate an air conditioning system with a low charge...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A missing air filter+improper rotation of the indoor blower+blower too small
A vacuum test+oil traces around fittings+soap bubble solution

47. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
A low refrigerant charge
An uninsulated suction line and a restricted metering device
Low discharge pressure - high suction pressure - and low amp draw
An increase of air leakage from ductwork

48. A system that is operating with a clear sight glass shows...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Condenser fans operating during a low ambient condition and a low suction pressure
The sight glass is full of liquid+the sight glass is full of gas
It is used to control refrigerant pressure in the compressor crankcase

49. 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
An overcharged system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
'G' to 'C'
A defective circuit breaker

50. A liquid-charged TXV bulb will...
Current in the compressor circuit
The discharge pressure increases and the amperage increases
Always have some liquid present in the bulb and diaphragm
Technician B