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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 three things can prevent an air conditioning system from absorbing 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 evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
The system has been overcharged+The system has air trapped in the condenser

2. 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
An undercharge and low ambient conditions
Low voltage and a faulty start relay
A blown fuse

3. The internal overload of an air conditioning compressor senses winding temperature and...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Current in the compressor circuit
Technician B
Both technicians are incorrect

4. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
Technician B
A start relay
Technician B

5. When using a vapor-charged TXV bulb - it is necessary to have...
50-65
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The sensing bulb at a lower temperature than the valve body
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

6. 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...
The low-side pressure will decrease and the evaporator coil will be partially frosted
20 to 30
A blown fuse
Clean the condenser coil

7. What problem or problems can cause low discharge and suction pressure...
A missing air filter+improper rotation of the indoor blower+blower too small
High superheat and low discharge pressure
An undercharged system+insufficient airflow over the evaporator coil
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

8. 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
The sensing bulb at a lower temperature than the valve body
The superheat will increase and the low-side pressure will decrease
Bad compressor valve
Broken rings+broken valves+seized bearings

9. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
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
An uninsulated TXV sensing bulb
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

10. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
3 psig
It would cause the low-side pressure to decrease

11. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An uninsulated suction line and a restricted metering device
Lack of airflow
An increase in suction pressure and an increase in discharge pressure
An undercharge and low ambient conditions

12. Superheat is found in an air conditioning system in the...
Evaporator and compressor
The external equalizer could be plugged
Bad compressor valve
Both technicians are correct

13. 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
A start capacitor and a solid-state relay
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
It keeps a constant superheat in the evaporator

14. 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
An overcharged system
110-120
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

15. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Technician B
Lack of airflow
('Y' and 'C') and ('G' and 'C')
A blown fuse

16. 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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17. 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...
Contains a solenoid coil and one or more sets of contacts
The internal overload is opened
50-65
Low superheat

18. A liquid-charged TXV bulb will...
A start capacitor and a solid-state relay
An uninsulated TXV sensing bulb
Always have some liquid present in the bulb and diaphragm
The internal overload is opened

19. 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
Evaporator and compressor
Short cycling and insufficient dehumidification
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

20. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
It would cause the low-side pressure to decrease
A sensing bulb improperly connected to the suction line
The superheat increases and the subcooling decreases
Technician B

21. Superheat is found in an air conditioning system in the...
Evaporator and compressor
Technician B
Short cycling and insufficient dehumidification
Partially frosted evaporator and high superheat

22. What are three methods for controlling a system's high-side pressure during low ambient conditions...
An increase in low-side pressure
20 to 30
Flooding the condenser - cycling condenser fans - and dampering condenser air
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

23. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A bad thermostat
A low refrigerant charge
A vacuum test+oil traces around fittings+soap bubble solution

24. What are the symptoms of an air conditioning system that has a low charge...
3 psig
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted

25. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
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 correct

26. 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...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Clean the condenser coil
Low voltage and a faulty start relay
An undercharge and low ambient conditions

27. 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
Lack of airflow
The internal overload is opened
Both technicians are incorrect
Flooding the condenser - cycling condenser fans - and dampering condenser air

28. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An uninsulated TXV sensing bulb

29. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
3 psig
Partially frosted evaporator and high superheat
Run with high head and high suction pressure

30. The best description of a relay would be...
A blown fuse
Contains a solenoid coil and one or more sets of contacts
Technician B
An open internal overload protector

31. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
Technician B
Clean the condenser coil
Evaporator and compressor

32. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
A defective circuit breaker
An undercharged system+insufficient airflow over the evaporator coil
Clean the condenser coil
Bad compressor valve

33. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The sensing bulb at a lower temperature than the valve body
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Run with high head and high suction pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air

34. Which of the following is a common cause of an excessively low superheat on a TXV system...
The sensing bulb at a lower temperature than the valve body
An increase of air leakage from ductwork
A sensing bulb improperly connected to the suction line
Technician B

35. What are three methods for controlling a system's high-side pressure during low ambient conditions...
An overcharged system
The low-side pressure will decrease and the evaporator coil will be partially frosted
Contains a solenoid coil and one or more sets of contacts
Flooding the condenser - cycling condenser fans - and dampering condenser air

36. Air filters should be replaced...
The sensing bulb at a lower temperature than the valve body
Whenever necessary
An undercharged system+insufficient airflow over the evaporator coil
Dirty condenser - bent condenser fins - and air recirculating over the condenser

37. What causes the automatic expansion valve to close...
An increase in low-side pressure
A low refrigerant charge
An increase of air leakage from ductwork
A blown fuse

38. 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
Technician A
Clean the condenser coil
The sensing bulb at a lower temperature than the valve body
Partially frosted evaporator and high superheat

39. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The external equalizer could be plugged
'G' to 'C'
Whenever necessary
A dirty condenser - recirculation of condenser air - and a defective condenser fan

40. A compressor having tight bearings would cause the current value to...
The external equalizer could be plugged
3 psig
Technician B
Rise more than normal

41. 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
It keeps a constant superheat in the evaporator
Both technicians are incorrect
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

42. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The low-side pressure will decrease and the evaporator coil will be partially frosted

43. A system that uses a thermal electric expansion valve...
Lack of airflow
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
Technician B

44. What component is most often the cause of a start capacitor failure...
A start relay
Technician B
('Y' and 'C') and ('G' and 'C')
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

45. Which of the following will cause excessive discharge pressures on an air conditioning system...
Short cycling and insufficient dehumidification
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An overcharged system
Low discharge pressure - high suction pressure - and low amp draw

46. Which of the following can cause low superheat in a TXV system...
Technician B
An uninsulated TXV sensing bulb
The sight glass is full of liquid+the sight glass is full of gas
Rise more than normal

47. 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 undercharge and low ambient conditions
Technician B
An uninsulated suction line and a restricted metering device
Technician A

48. 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
A blown fuse
An uninsulated suction line and a restricted metering device
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician A

49. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Technician B
Short cycling and insufficient dehumidification
An uninsulated suction line and a restricted metering device
20 to 30

50. 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 could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A vacuum test+oil traces around fittings+soap bubble solution