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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 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
Both technicians are incorrect
110-120
An increase in low-side pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

2. What are the symptoms of an air conditioning system that has a low charge...
Technician A is correct
The low-side pressure will decrease and the evaporator coil will be partially frosted
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

3. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
An uninsulated TXV sensing bulb
The oil pump pressure and the crankcase pressure
Technician B

4. Which of the following will cause excessive discharge pressures on an air conditioning system...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A plugged filter drier
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B

5. 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
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A vacuum test+oil traces around fittings+soap bubble solution
Whenever necessary

6. What type of problems can be caused by an oversized air conditioning system...
Evaporator and compressor
A defective circuit breaker
Short cycling and insufficient dehumidification
Technician B

7. The best description of a relay would be...
A vacuum test+oil traces around fittings+soap bubble solution
Contains a solenoid coil and one or more sets of contacts
An uninsulated suction line and a restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure

8. 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
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A blown fuse
An increase of air leakage from ductwork

9. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Technician B
An overcharged system
The superheat increases and the subcooling decreases
20 to 30

10. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
'G' to 'C'
A vacuum test+oil traces around fittings+soap bubble solution
The oil pump pressure and the crankcase pressure

11. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
An uninsulated suction line and a restricted metering device
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan

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
It keeps a constant superheat in the evaporator
Broken rings+broken valves+seized bearings
The internal overload is opened
The sight glass is full of liquid+the sight glass is full of gas

13. 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...
An overcharged system
Technician B
High superheat and low discharge pressure
The discharge pressure increases and the amperage increases

14. 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
Partially frosted evaporator and high superheat
An open internal overload protector
An increase in low-side pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

15. 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
An open internal overload protector
Partially frosted evaporator and high superheat
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

16. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Rise more than normal
Flooding the condenser - cycling condenser fans - and dampering condenser air
Lack of airflow
A restricted metering device

17. 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
The sensing bulb at a lower temperature than the valve body
A sensing bulb improperly connected to the suction line
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A bad thermostat

18. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
An increase of air leakage from ductwork
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
20 to 30

19. A restricted air filter in an air conditioning system can be identified by...
Rise more than normal
Low superheat
Technician B
An uninsulated suction line and a restricted metering device

20. A hard-start kit consists of...
A start capacitor and a solid-state relay
The superheat increases and the subcooling decreases
20 to 30
An acid-core suction line drier

21. What component is most often the cause of a start capacitor failure...
Both technicians are incorrect
A start relay
A plugged filter drier
Technician B

22. A hard-start kit consists of...
An uninsulated TXV sensing bulb
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A start capacitor and a solid-state relay
A dirty condenser - recirculation of condenser air - and a defective condenser fan

23. 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
A missing air filter+improper rotation of the indoor blower+blower too small
The external equalizer could be plugged
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The low-side pressure will decrease and the evaporator coil will be partially frosted

24. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Contains a solenoid coil and one or more sets of contacts
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Both technicians are incorrect
Dirty condenser - bent condenser fins - and air recirculating over the condenser

25. Superheat is found in an air conditioning system in the...
Evaporator and compressor
The superheat will increase and the low-side pressure will decrease
Technician B
3 psig

26. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
20 to 30
Broken rings+broken valves+seized bearings
An uninsulated suction line and a restricted metering device

27. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The internal overload is opened
'G' to 'C'
An increase in suction pressure and an increase in discharge pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

28. 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...
Technician B
Low voltage and a faulty start relay
A blown fuse
The superheat increases and the subcooling decreases

29. The temperature range of the suction line from an air conditioning system should be...
The low-side pressure will decrease and the evaporator coil will be partially frosted
50-65
Broken rings+broken valves+seized bearings
An increase of air leakage from ductwork

30. 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
3 psig
Both technicians are correct
Dirty condenser - bent condenser fins - and air recirculating over the condenser

31. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
3 psig
It keeps a constant superheat in the evaporator

32. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Flooding the condenser - cycling condenser fans - and dampering condenser air
The sensing bulb at a lower temperature than the valve body
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Clean the condenser coil
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The sensing bulb at a lower temperature than the valve body

34. The internal overload of an air conditioning compressor senses winding temperature and...
Technician A is correct
110-120
Partially frosted evaporator and high superheat
Current in the compressor circuit

35. 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 defective circuit breaker
Condenser fans operating during a low ambient condition and a low suction pressure
An increase in suction pressure and an increase in discharge pressure
A start relay

36. The technician observes that the compressor is not operating. The compressor windings read 5 ohms start to run - run to common is opened - and start to common is opened. The technician concludes that...
Technician B
Technician B
The internal overload is opened
Technician A is correct

37. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Always have some liquid present in the bulb and diaphragm
Bad compressor valve
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Run with high head and high suction pressure

38. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
High suction pressure and low superheat
An undercharge and low ambient conditions
Contains a solenoid coil and one or more sets of contacts
An uninsulated TXV sensing bulb

39. 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
Technician A
The external equalizer could be plugged
Clean the condenser coil
Rise more than normal

40. What component is most often the cause of a start capacitor failure...
A start relay
An increase in suction pressure and an increase in discharge pressure
The internal overload is opened
Run with high head and high suction pressure

41. A liquid-charged TXV bulb will...
An undercharged system+insufficient airflow over the evaporator coil
It would cause the low-side pressure to decrease
Low voltage and a faulty start relay
Always have some liquid present in the bulb and diaphragm

42. 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 bad thermostat
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A missing air filter+improper rotation of the indoor blower+blower too small

43. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Broken rings+broken valves+seized bearings
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An uninsulated TXV sensing bulb

44. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Technician B
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
Low discharge pressure - high suction pressure - and low amp draw

45. 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...

46. 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
Technician A is correct
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The internal overload is opened
Technician B

47. 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 restricted metering device
The external equalizer could be plugged
Technician B
A bad thermostat

48. 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
Whenever necessary
Technician B
Low superheat

49. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
Clean the condenser coil
A restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

50. What is the purpose of a CPR valve...
A low refrigerant charge
A plugged filter drier
It is used to control refrigerant pressure in the compressor crankcase
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay