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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 type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
It is used to control refrigerant pressure in the compressor crankcase
The superheat increases and the subcooling decreases
A bad thermostat

2. What is the purpose of a CPR valve...
Bad compressor valve
A start relay
Flooding the condenser - cycling condenser fans - and dampering condenser air
It is used to control refrigerant pressure in the compressor crankcase

3. 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
It is used to control refrigerant pressure in the compressor crankcase
Both technicians are incorrect
An overcharged system
Technician B

4. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
Short cycling and insufficient dehumidification
('Y' and 'C') and ('G' and 'C')
110-120
A blown fuse

5. What problem or problems can cause low discharge and suction pressure...
The sight glass is full of liquid+the sight glass is full of gas
Evaporator and compressor
An undercharged system+insufficient airflow over the evaporator coil
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

6. The internal overload of an air conditioning compressor senses winding temperature and...
The internal overload is opened
High superheat and low discharge pressure
A sensing bulb improperly connected to the suction line
Current in the compressor circuit

7. When using a vapor-charged TXV bulb - it is necessary to have...
A sensing bulb improperly connected to the suction line
Partially frosted evaporator and high superheat
Technician A is correct
The sensing bulb at a lower temperature than the valve body

8. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The sensing bulb at a lower temperature than the valve body
A blown fuse
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The superheat will increase and the low-side pressure will decrease

9. Superheat is found in an air conditioning system in the...
Evaporator and compressor
110-120
The low-side pressure will decrease and the evaporator coil will be partially frosted
It keeps a constant superheat in the evaporator

10. 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
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The low-side pressure will decrease and the evaporator coil will be partially frosted

11. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Technician B
An undercharge and low ambient conditions
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Short cycling and insufficient dehumidification

12. 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
Technician B
20 to 30
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

13. 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
An overcharged system
A start relay
Low discharge pressure - high suction pressure - and low amp draw

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

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 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Contains a solenoid coil and one or more sets of contacts
Technician B

17. A commercial customer calls on a 90
An overcharged system
The system has been overcharged+The system has air trapped in the condenser
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Clean the condenser coil

18. What are the symptoms of an air conditioning system that has a low charge...
The low-side pressure will decrease and the evaporator coil will be partially frosted
The oil pump pressure and the crankcase pressure
A start relay
The external equalizer could be plugged

19. 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...
50-65
An open internal overload protector
Condenser fans operating during a low ambient condition and a low suction pressure
A low refrigerant charge

20. 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
Low discharge pressure - high suction pressure - and low amp draw
Clean the condenser coil
Technician B

21. 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
Both technicians are correct
An uninsulated suction line and a restricted metering device
A start capacitor and a solid-state relay

22. 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
20 to 30
Technician A is correct
Broken rings+broken valves+seized bearings
It is used to control refrigerant pressure in the compressor crankcase

23. 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
Partially frosted evaporator and high superheat
Technician A
The sensing bulb at a lower temperature than the valve body

24. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Technician B
An increase in suction pressure and an increase in discharge pressure
The superheat increases and the subcooling decreases
3 psig

25. 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
Both technicians are correct
Contains a solenoid coil and one or more sets of contacts
Technician B
Run with high head and high suction pressure

26. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An increase of air leakage from ductwork
Whenever necessary

27. Which of the following will cause excessive discharge pressures on an air conditioning system...
Increases starting torque
An acid-core suction line drier
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

28. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The superheat increases and the subcooling decreases
110-120
The superheat will increase and the low-side pressure will decrease
A dirty condenser - recirculation of condenser air - and a defective condenser fan

29. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
An undercharge and low ambient conditions
Evaporator and compressor
The superheat increases and the subcooling decreases
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

30. 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 start capacitor and a solid-state relay
Technician B
High suction pressure and low superheat
The system has been overcharged+The system has air trapped in the condenser

31. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
An increase in suction pressure and an increase in discharge pressure
A start relay
A restricted metering device

32. 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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33. Which of the following can cause low superheat in a TXV system...
Low voltage and a faulty start relay
An uninsulated TXV sensing bulb
An increase in low-side pressure
Low discharge pressure - high suction pressure - and low amp draw

34. Which of the following is a possible cause for a compressor to overheat...
An acid-core suction line drier
A low refrigerant charge
Technician B
Evaporator and compressor

35. 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
Technician A
A start relay
20 to 30
Both technicians are correct

36. 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
A sensing bulb improperly connected to the suction line
Clean the condenser coil
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The internal overload is opened

37. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Both technicians are correct
The superheat increases and the subcooling decreases
Technician B
A start relay

38. A compressor having tight bearings would cause the current value to...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An acid-core suction line drier
It keeps a constant superheat in the evaporator
Rise more than normal

39. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
A blown fuse
An undercharge and low ambient conditions
The superheat increases and the subcooling decreases

40. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
50-65
Technician B
Low voltage and a faulty start relay

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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician A is correct

42. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
A defective circuit breaker
20 to 30
Broken rings+broken valves+seized bearings

43. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
Rise more than normal
The discharge pressure increases and the amperage increases
Lack of airflow

44. What are common methods that are used for leak-testing a system...
The low-side pressure will decrease and the evaporator coil will be partially frosted
The internal overload is opened
The superheat will increase and the low-side pressure will decrease
A vacuum test+oil traces around fittings+soap bubble solution

45. The temperature range of the suction line from an air conditioning system should be...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
50-65
('Y' and 'C') and ('G' and 'C')
The internal overload is opened

46. A restricted air filter in an air conditioning system can be identified by...
It would cause the low-side pressure to decrease
Low superheat
Clean the condenser coil
The external equalizer could be plugged

47. A hard-start kit for 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
Increases starting torque
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Clean the condenser coil

48. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Low discharge pressure - high suction pressure - and low amp draw
An overcharged system
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician A

49. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Clean the condenser coil
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The discharge pressure increases and the amperage increases

50. What are two common symptoms of refrigerant leaks in an air conditioning system...
Technician A
Evaporator and compressor
Partially frosted evaporator and high superheat
An increase in low-side pressure