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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. 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...
Always have some liquid present in the bulb and diaphragm
The discharge pressure increases and the amperage increases
High superheat and low discharge pressure
It is used to control refrigerant pressure in the compressor crankcase

2. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
The superheat will increase and the low-side pressure will decrease
An increase in low-side pressure
Broken rings+broken valves+seized bearings
Run with high head and high suction pressure

3. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
A bad thermostat
Technician B
The sensing bulb at a lower temperature than the valve body

4. The internal overload of an air conditioning compressor senses winding temperature and...
A bad thermostat
Current in the compressor circuit
The oil pump pressure and the crankcase pressure
An overcharged system

5. What are the symptoms of an air conditioning system that has a low charge...
Both technicians are incorrect
A missing air filter+improper rotation of the indoor blower+blower too small
Technician A is correct
The low-side pressure will decrease and the evaporator coil will be partially frosted

6. What is the common cause of a compressor burnout...
A low refrigerant charge
Technician A
'G' to 'C'
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

7. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
An increase in low-side pressure
A plugged filter drier

8. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A start relay
The sight glass is full of liquid+the sight glass is full of gas
Flooding the condenser - cycling condenser fans - and dampering condenser air
An open internal overload protector

9. What is the common cause of a compressor burnout...
3 psig
An uninsulated TXV sensing bulb
Both technicians are incorrect
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

10. What is the purpose of an EPR valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A sensing bulb improperly connected to the suction line
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician A

11. A restricted air filter in an air conditioning system can be identified by...
Low superheat
The system has been overcharged+The system has air trapped in the condenser
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Clean the condenser coil

12. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A bad thermostat
Both technicians are incorrect
Lack of airflow
20 to 30

13. 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 system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
High suction pressure and low superheat
The oil pump pressure and the crankcase pressure
Whenever necessary

14. 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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15. 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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16. 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 increase in low-side pressure
Increases starting torque
Technician B
Technician A

17. 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...
A bad thermostat
An overcharged system
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B

18. 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
Technician A
3 psig
A defective circuit breaker
A bad thermostat

19. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
An increase in suction pressure and an increase in discharge pressure
A plugged filter drier
An uninsulated TXV sensing bulb
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
It is used to control refrigerant pressure in the compressor crankcase
Technician B
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

21. 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
Evaporator and compressor
Technician B
A start relay
Lack of airflow

22. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A start relay
High suction pressure and low superheat
The external equalizer could be plugged
Technician B

23. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
Bad compressor valve
A restricted metering device

24. 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
Always have some liquid present in the bulb and diaphragm
Broken rings+broken valves+seized bearings
Bad compressor valve
A sensing bulb improperly connected to the suction line

25. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Both technicians are correct
A plugged filter drier
It would cause the low-side pressure to decrease
Low voltage and a faulty start relay

26. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A restricted metering device
Both technicians are correct

27. 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...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Low voltage and a faulty start relay
Low superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

28. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Clean the condenser coil
A missing air filter+improper rotation of the indoor blower+blower too small
A restricted metering device

29. 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...
A start capacitor and a solid-state relay
High superheat and low discharge pressure
'G' to 'C'
Increases starting torque

30. Which of the following could be the cause for a system's discharge and suction pressure being low...
The sight glass is full of liquid+the sight glass is full of gas
High superheat and low discharge pressure
3 psig
A restricted metering device

31. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Both technicians are incorrect
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An open internal overload protector
The system has been overcharged+The system has air trapped in the condenser

32. 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
A sensing bulb improperly connected to the suction line
An open internal overload protector
An overcharged system

33. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
The superheat increases and the subcooling decreases
Broken rings+broken valves+seized bearings
Increases starting torque

34. What three things can prevent an air conditioning system from releasing heat at the proper rate...
It is used to control refrigerant pressure in the compressor crankcase
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Low voltage and a faulty start relay
A bad thermostat

35. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A low refrigerant charge
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Short cycling and insufficient dehumidification
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

36. A liquid-charged TXV bulb will...
Both technicians are incorrect
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
Always have some liquid present in the bulb and diaphragm

37. 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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38. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
Technician B
An open internal overload protector
A bad thermostat

39. Insufficient airflow can be caused by...
Bad compressor valve
Contains a solenoid coil and one or more sets of contacts
An increase of air leakage from ductwork
Increases starting torque

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
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
Low voltage and a faulty start relay
Rise more than normal

41. Which of the following is a possible cause for a compressor to overheat...
The superheat increases and the subcooling decreases
A low refrigerant charge
An uninsulated suction line and a restricted metering device
An open internal overload protector

42. Which of the following can cause low superheat in a TXV system...
An increase in suction pressure and an increase in discharge pressure
An uninsulated TXV sensing bulb
Run with high head and high suction pressure
Evaporator and compressor

43. 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
A vacuum test+oil traces around fittings+soap bubble solution
Short cycling and insufficient dehumidification
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

44. 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...
An overcharged system
A sensing bulb improperly connected to the suction line
The internal overload is opened
Technician A

45. 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 undercharge and low ambient conditions
Clean the condenser coil
A bad thermostat
A blown fuse

46. 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 has been overcharged+The system has air trapped in the condenser
3 psig
Technician A
Clean the condenser coil

47. 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...
A low refrigerant charge
Low voltage and a faulty start relay
A restricted metering device
A sensing bulb improperly connected to the suction line

48. What is the purpose of an EPR valve...
'G' to 'C'
Always have some liquid present in the bulb and diaphragm
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

49. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Contains a solenoid coil and one or more sets of contacts
An acid-core suction line drier
Current in the compressor circuit

50. The best description of a relay would be...
An undercharged system+insufficient airflow over the evaporator coil
An overcharged system
The external equalizer could be plugged
Contains a solenoid coil and one or more sets of contacts