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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 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
Always have some liquid present in the bulb and diaphragm
The system has been overcharged+The system has air trapped in the condenser
Clean the condenser coil

2. 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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3. 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
Evaporator and compressor
The external equalizer could be plugged
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

4. 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
The sight glass is full of liquid+the sight glass is full of gas
An uninsulated suction line and a restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

5. What are two common symptoms of refrigerant leaks in an air conditioning system...
The superheat increases and the subcooling decreases
Partially frosted evaporator and high superheat
Evaporator and compressor
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

6. 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
The oil pump pressure and the crankcase pressure
Technician B
('Y' and 'C') and ('G' and 'C')
A dirty condenser - recirculation of condenser air - and a defective condenser fan

7. A hard-start kit for an air conditioning system...
Both technicians are correct
A low refrigerant charge
Increases starting torque
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

8. 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
Whenever necessary
Lack of airflow
The external equalizer could be plugged
Run with high head and high suction pressure

9. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Condenser fans operating during a low ambient condition and a low suction pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
High suction pressure and low superheat
50-65

10. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
3 psig
Clean the condenser coil
A dirty condenser - recirculation of condenser air - and a defective condenser fan

11. 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 undercharged system+insufficient airflow over the evaporator coil
3 psig
Both technicians are incorrect

12. Which of the following is a common cause of an excessively low superheat on a TXV system...
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
Short cycling and insufficient dehumidification
A sensing bulb improperly connected to the suction line

13. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
Clean the condenser coil
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

14. Which of the following can cause excessive subcooling...
The internal overload is opened
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Both technicians are incorrect
An overcharged system

15. 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
'G' to 'C'
A defective circuit breaker
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

16. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Bad compressor valve
An uninsulated suction line and a restricted metering device
A low refrigerant charge
The discharge pressure increases and the amperage increases

17. A hard-start kit consists of...
A start capacitor and a solid-state relay
The internal overload is opened
Low superheat
Technician A is correct

18. When troubleshooting a split-system air conditioner - it is found that the compressor motor is humming but not starting. Technician A says that it could be an open internal overload protector. Technician B says that it could be a blown fuse. Which te
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Both technicians are incorrect
A missing air filter+improper rotation of the indoor blower+blower too small
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

19. 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
Technician A is correct
The discharge pressure increases and the amperage increases
Short cycling and insufficient dehumidification
Contains a solenoid coil and one or more sets of contacts

20. 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
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
Rise more than normal

21. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
110-120
Current in the compressor circuit
It would cause the low-side pressure to decrease

22. 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
Technician B
Partially frosted evaporator and high superheat
Condenser fans operating during a low ambient condition and a low suction pressure

23. 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
The discharge pressure increases and the amperage increases
An open internal overload protector
Both technicians are incorrect
The superheat will increase and the low-side pressure will decrease

24. What are two problems that can cause an air conditioning system to have an excessively high superheat...
The superheat increases and the subcooling decreases
An overcharged system
An uninsulated TXV sensing bulb
An uninsulated suction line and a restricted metering device

25. 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 is correct
Clean the condenser coil
Low voltage and a faulty start relay
The sensing bulb at a lower temperature than the valve body

26. 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 start capacitor and a solid-state relay
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician A
The discharge pressure increases and the amperage increases

27. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
The superheat increases and the subcooling decreases
Low discharge pressure - high suction pressure - and low amp draw
A restricted metering device
An acid-core suction line drier

28. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An acid-core suction line drier
A dirty condenser - recirculation of condenser air - and a defective condenser fan

29. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A defective circuit breaker
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
High superheat and low discharge pressure
An open internal overload protector

30. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
An acid-core suction line drier
A blown fuse
Technician B

31. A liquid-charged TXV bulb will...
It keeps a constant superheat in the evaporator
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
Always have some liquid present in the bulb and diaphragm

32. 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
Broken rings+broken valves+seized bearings
Technician B
A defective circuit breaker
The discharge pressure increases and the amperage increases

33. What type of problems can be caused by an oversized air conditioning system...
Low voltage and a faulty start relay
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
A vacuum test+oil traces around fittings+soap bubble solution

34. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Both technicians are incorrect
50-65
Lack of airflow
Always have some liquid present in the bulb and diaphragm

35. 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...
The system has been overcharged+The system has air trapped in the condenser
An uninsulated TXV sensing bulb
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Low voltage and a faulty start relay

36. A system that is operating with a clear sight glass shows...
110-120
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The sight glass is full of liquid+the sight glass is full of gas
A low refrigerant charge

37. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
Condenser fans operating during a low ambient condition and a low suction pressure
Partially frosted evaporator and high superheat
50-65

38. 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 open internal overload protector
Low discharge pressure - high suction pressure - and low amp draw
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The internal overload is opened

39. 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...
The sensing bulb at a lower temperature than the valve body
High superheat and low discharge pressure
Low discharge pressure - high suction pressure - and low amp draw
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

40. 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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41. 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
It keeps a constant superheat in the evaporator
Technician A is correct
A vacuum test+oil traces around fittings+soap bubble solution
50-65

42. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
An overcharged system
Current in the compressor circuit
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

43. 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
Always have some liquid present in the bulb and diaphragm
20 to 30
An increase in low-side pressure
Both technicians are correct

44. Which of the following will cause excessive discharge pressures on an air conditioning system...
It is used to control refrigerant pressure in the compressor crankcase
Bad compressor valve
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

45. What three things can prevent an air conditioning system from releasing heat at the proper rate...
An uninsulated TXV sensing bulb
Current in the compressor circuit
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B

46. 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
3 psig
A missing air filter+improper rotation of the indoor blower+blower too small
An undercharge and low ambient conditions

47. 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 uninsulated TXV sensing bulb
A restricted metering device
The internal overload is opened
A dirty condenser - recirculation of condenser air - and a defective condenser fan

48. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
Low voltage and a faulty start relay
Technician B
Both technicians are correct

49. A system that is operating with a clear sight glass shows...
A plugged filter drier
('Y' and 'C') and ('G' and 'C')
The sight glass is full of liquid+the sight glass is full of gas
Partially frosted evaporator and high superheat

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